"Shunt" diodes with resistors? Answered

I'm making diode bridges to have a nice supply of DC. I'm making a high voltage bridge for a 7.5kv nst and a low voltage bridge for regular 120v wall outlet . My high voltage bridge im going to make with several 1N4007 but i read that they should be "shunted" with 10Mohm resistors im not sure what is meant by this. Does it mean resistor, diode, resistor, diode or does it mean diode and resistor, diode and resistor. The pic says it better than i do.  Also, do i need resistors for a bridge for 120v bridge?, im going to use the diodes from a fluorescent light power supply.

Asked by jaydenr 8 years ago  |  last reply 8 years ago


how do i connect a shunt to an analogue ammeter?

How do i connect a shunt to an analogue ammeter? can some please draw me up a diagram (even crude paint one will do ) of how i wire up an ammeter to a device such as a motor or something with one input and one output (+ and -) while using a shunt? shunts really have me confused and i havent yet been able to figure out how they work logically

Asked by oldmanbeefjerky 7 years ago  |  last reply 7 years ago


Can I use the same resistors for current shunt AND transistor balancing?

In my pursuit for a LPSU design, to get more HFe gain, higher current capability, decrease Vce dropout, improve thermals, etc. I would use 2 (or more) pass transistors. This requires load balancing resistors, so I thought I'd get clever and use these balancing resistors to also measure current for my current limiting capability! See pictures and explanation below. IMPORTANT: The second schematic implys the use of 100R resistors, that is a mistake, they are supposed to be 0.1 ohm, or around that figure. Details: The first picture below is a simplified diagram of how I currently have current feedback implemented. I generate a fixed (user adjustable) voltage across a 500R resistor via a current sink and an error amp (currently LM358) drives output pass transistor(s). Because the op amp drives the output to ensure the inputs are the same, the output current can be precisely regulated. It maintains a precise voltage differential across the shunt by means of the pass transistor. I don't want to take the naive approach with multiple resistances in the path of the current flow from the unregulated supply to the output, for obvious reasons. I could instead just measure the Vdrop on one of these balancing resistors, but that assumes that the current through those resistors is identical, which is not the case. So instead, what if I expand a bit on the first schematic, leading to the last schematic? Would that work? I want to understand the mathematical analysis behind it to prove it does work. 

Asked by -max- 2 years ago  |  last reply 2 years ago


Does anyone have any ideas on how to build a simple but reliable motor controller for a high voltage (500v) DC motor?

I need to make a high voltage (500V), high current (20A) DC motor controller that uses a DC power source. It must be reliable and last a long time, and it also needs to be able control the speed of the motor from zero and up. Any ideas on building one or perhaps one that I can buy? Thanks!

Asked by ANDY! 5 years ago  |  last reply 5 years ago


Wiring Digital Voltmeter Ammeter Without Shunt

I have this:  http://www.ebay.com/itm/271210262267?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649. They say is can it be used up to 10 amps without a shunt, but I can't find wiring diagram. I am trying to wire into 50 watt led light. I know the small red and black go to power source. I am not sure how to connect 3 thick wires( red, black, yellow) without a shunt. I am only trying to meter 1.5 amp circuit.  Here's what I am trying to wire. Thank you

Posted by flatfish 5 years ago  |  last reply 4 years ago


Troubleshooting Christmas Mini-Light Strings

I searched Instructables to be certain I am not covering something someone else has already done, but found nothing.  Here is an excellent article on troubleshooting a bad string of Christmas mini-lights. (I do not know the author and am not connected to him in any way.)  I know of three occurrences of non-working light strings from this year's celebrations. In the first case, the woman who owns the Christmas tree simply bought a new string of lights and hung the new lights over the old string attached at the factory to her synthetic tree. I did not see her tree and cannot say what the cause of the malfunction was. In the second occurrence we put up a synthetic tree with two strings of factory installed lights, one for the bottom half of the tree and one for the top half of the tree. The string on the top half worked some of the time, but then would go out. Typically one suspects a bad bulb. That is also the general suggestion made in the very fine article I linked above. However, that proved not to be the problem. Rather, the problem was the very cheap electrical plug. I cut the plug from the string so I could open it and determine exactly where and how it failed in order to satisfy my own curiosity. Installing a new male plug solved the problem. In the third case, my daughter had a string near the top of her tree that was "out," but not completely at the top. I had limited tools and resources, but plugging the bad string into a different molded female plug brought it back to life. The moral of the story is that while a bad bulb is a frequent source of problems, the molded male and female plugs on these inexpensive light strings are often held together only by a lick and a promise, and fail easily. Giving the molded plugs a hard look is much easier and faster than removing and testing bulb after bulb. The first photo shows an extension cord with molded plugs from three strings plugged into the extension cord. The second photo shows the bad male plug on our tree, and I am using my multi-meter to test for continuity between the brass plug blade and the load end of one of the tiny fuses inside the plug. That part tests "good." The other fuse tested "good," too. In the third photo I inserted a straight pin into the wire and tested for a circuit from the brass blades to the wire. Both sides failed this test.  A multi-meter can easily test what I needed to find this problem. I would have needed to strip away some insulation from the wire or stick a straight pin through the wire to obtain a reading with my multi-meter. But, by this time I had bought a hum tester with a high and a low range for checking different voltage ranges on an AC circuit. It led me to know the plug was the problem. 

Posted by Phil B 6 years ago  |  last reply 2 years ago


Are the old metal cased NSTs filled with tar? Answered

I've got an old NST and am interested in removing the shunts, before I do anything I would like to know if they (old NSTs) are filled with tar? It is a 12kV 23mA.

Asked by The MadScientist 7 years ago  |  last reply 7 years ago


How can I make an ammeter for ~5V DC up to 3A? I want to connect this ammeter to a microcontroller.

I want to connect this ammeter to a microcontroller ADC and display it on 7-segment displays. I guess a 10W resistor ~0.1ohms or something will be involved. I can obtain them easily. I want to make an inline USB ammeter. I am experienced with PICAXE microcontrollers and surface-mount.

Asked by jdorne 6 years ago  |  last reply 6 years ago


Help with T5 Fluorescent Light

I'm adding a 9" T5 UV light to a small project I'm making. I found a cheap G6T5 Bulb and a Ballast but when I went to purchase the Sockets for it, I ran into a problem. The Bi-pin T5 sockets come in Shunted & Non Shunted and I have no idea which one I need. What is the difference and how would I tell which one to buy to finish my light? Once I have all this I'll have to figure out how to wire the thing. But first I need to know which sockets I need to buy. THANKS!!

Posted by mrreno 11 years ago  |  last reply 11 years ago


Wind Power Charge Regulators

Hello!! I need some help here...I am very "green" when it comes to alternative energy, so bear with me please! I recently decided to put together a small wind generation system to power my workshop. System is comprised of a 38v Ametek PMDC motor, 6.8' tri-blade array for propulsion. I also intend on installing a 2000 to 3000 watt modfied sine wave inverter powered by my battery bank to provide AC voltage to the shop. I want to be able to used the majority of the power created by my wind generator. I understand the concept of using a "shunt" but do not have a need for hot water or useless lighting. My question is this, would the Flexcharge NC25A charge controller (www.flexcharge.com/flexcharge_usa/products/nc25a/nc25a.htm) be sufficient enough to used in this system? Or is there something else out there that would maintain my battery bank without shunting the load when the bank is fully charged....Thanks in advance.

Posted by NMCBDet23 10 years ago  |  last reply 10 years ago


HOW do you cut and then rewire the new led christmas lights?

I bought a 35 light strand hoping to make 7ea , 5 light strands for a project but couln't rewire without burning up the leds ! ? is there some sort of current limiting device built into the strands ?  also notice they are wired with 3 wires for shunting as a are the old mini lights. no matter how i try to rewire these lights they burn out every time!!

Asked by nation 7 years ago  |  last reply 7 years ago


Why don't people modify MOT's for high voltage? Answered

Why don't people modify MOT's for high voltage? I just did I left about 3 layers of primary windings, removed the middle coil and the shunts put it back together then submerged it in oil, I also removes a couple of layers of the secondary windings to get rid of the resin so the oil can get in. It worked amazingly I don't understand why people don't do it.

Asked by The MadScientist 7 years ago  |  last reply 7 years ago


How do I use the LM3914H bargraph voltmeter circuit to switch 2 amp, 12 VDC loads instead of LED's?

I'm thinking either power transistors or relays instead of the LED's, but designing the actual circuit is a little beyond me. I'd actually like to build two of these and use the second to measure DC current of 0 - 20 amps, I'm thinking measuring the voltage drop across a shunt resistor...

Asked by stevekrawcheck 6 years ago  |  last reply 6 years ago


MOT confused?

Been watching a lot of videos on youtube about increasing the voltage on Microwave oven transformers!. what i cant undrstand is when people take out the secondry windings of the transformer & replace it with a few turns of 10 gauge wire to increase the power how does it work? as from  what i've seen the 10 gauge wire still has the insulstion on it so how does the current cant get through to produce extra power?. Also what do the shunts do in the workings of the transformer?. can anyone explain this to me in laymans terms!. Thank's, Tezza1.

Asked by tezza1 7 years ago  |  last reply 7 years ago


full deflection of analogue multimeter needle? Answered

Hi, I accidently kept the dial at 25ma, instead of 250v ac of my analogue multimeter, the needle jumped twice, i realised my mistake and immediately disconnected, the problem now is when ever i check any reading including ohms check, the needle deflects fully, any idea what  i must have damaged. Hi, I just added the front and back of the PCB, if u gentlemen could identify, the shunt resistor and the current limiting resistor, will be of great hep

Asked by patrickvaz 8 years ago  |  last reply 8 years ago


High Current measurement using Arduino?

I need to measure Current from a welding machine to make a alarm if it goes down below some level for ensuring better quality.The current normally set is of the order of 200A max with around 100V DC.Not sure if i could use some clamp-on meters and decode the values. Shunt resistors may be a better option. But to make a signal conditioner to convert the ma output will be a problem i guess..is there something i can do with Arduino.. any ideas guys....?

Asked by chuppandi 6 years ago  |  last reply 6 years ago


High Current measurement

I need to measure Current from a welding machine to make a alarm if it goes down below some level for ensuring better quality of welding. The current normally set is of the order of 200A max with around 100V DC.Not sure if i could use some clamp-on meters and pass those values out to Arduino for switching circuit. Shunt resistors may be a better option. But to make a signal conditioner to convert the ma output will be a problem i guess..is there something i can do with Arduino.. any ideas guys....? Thanks in advance Chuppandi

Posted by chuppandi 6 years ago


home made MOT pork chop!

I have a crazy idea to make a transformer for a tesla coil useing two MOTs that are exactly the same, Then cutting them so you only have the 2 "E" core sections, Pull off the primary off one, flip the secondry so its out of phase, put the two cores together and clamp them so they cant move. put some extra shunts in to help limit current, hook up the primary to a variac and turn up the power slowly and test the arc. PORK CHOP! pole pig?

Posted by inductionheat! 9 years ago  |  last reply 7 years ago


Having trouble measuring accurate voltage with arduino.

For a week now I’m trying to get very precise voltage readings with no luck so far. I’m using a voltage shunt regulator (LM431) for reference but still. My goal is to read values low as a 1mv change. I’m using a voltage divider to convert 38 volts to 4v (According to my vref). I've read that 10 bit ADC in atmega328 is enough for this job. Is it or am I doing something wrong? Thanks P.S i have made a lot on changes to my circuit so please go over to my new link to get up to date. Ive read all of your feedback and tried to implement it. Thanks a lot for all your answers.  LINK: https://www.instructables.com/answers/Having-trouble-measuring-voltage-with-arduino/

Asked by faraz ahmed khan 1 year ago  |  last reply 1 year ago


Voltage Regulator

EDIT: Anyone Interested please check below posts, this is one is obsoleteHello!I need a voltage smoother and regulator on my circuit(attached below)it is a modified shunt charge controller circuit.It converts the Tri phase alternating current to DC and feeds it into the circuit.The regulator will have to be attachable to the BATTERIES wire in the circuit.It should not consume more than 1v power on its own.My Vout to the battery currently is fluctuating.I will need the to be a stable 12v to charge the batteries. A potentiometer will have to adjust current.I will calibrate current according to my battery bank needs.Led 1 indicates 'charging' Led 2 indicates 'Dump'And Please forgive my circuit diagram design(it looks like crap)but works like gold.Also do NOT suggest huge changes to my controller for the regulator to work. Small suggestions to make it more effective,useful like change the zener diode power rating will be welcome.P.S- Its for my hydro project.Check it out at https://www.instructables.com/community/Help-Hydro-power/Kabir

Posted by mhkabir 9 years ago  |  last reply 9 years ago


Accurate Variable Current Sink? Differential Voltage Reference?

Some background: I have recently aquired a few really nice (and really heavy!!!) LAMBDA power supplies, The largest one supplies 24V, and up to 9A, but has annoying foldback current limiting, which causes the output shut off when even a short period overload (like inrush current) is detected. What I want: I would like to modify this power supply to give me (ideally) completly variable 0-15v dual rail voltages & 0-5A adjustable current limit, & I would like this to be controlled with arduino so that I can use a nice LCD display and control the supply remotely with a bluetooth or wifi app, and possibly do some data logging which could come in handy for energy measurements and stuff! My current PSU design: The schematic below is what I've currently built in LTspice. Both the voltage & current regulation work. The voltage across the (+) and (-) inputs of the current error amplifier should be the sum of the voltage drop across the shunt resistor and the voltage drop of a voltage reference, so when the voltage on the shunt resistor exceeds the voltage of that reference, the op amp will start to limit current by reducing the bias voltage on the pass transistor. This V_ref needs to be both variable and accurate, but since this V_ref is a differential voltage between the output of the pass transistor and the input of the error amp, I came up with the clever idea to use a resistor there and a variable constant current sink. That way the constant current through that resistor results in a fixed V_drop across it. With a bit of fudging around with it, I was able to make it work. However, I need to replace that "ideal" current sink with a real one. I tried using the classic NPN-based one, but it wasn't good enough. I then attempted to make the slightly improved version of that current sink with a spare op amp, although this worked, it would stop pulling current once the voltage fell below what was being maintained across the small resistor. The REAL question: Would anyone happen to know how to make a really accurate and variable current sink? Maybe if this is not such a great idea, what other methods can I use to generate a fixed differential voltage?

Asked by -max- 3 years ago  |  last reply 3 years ago


Do avalanching diodes "latch up"?

While working and revising my flyback driver design, I had one of the 1N4148 diodes that I was using as protection get cooked!  (it seemed to fail short circuit) I have not tested to see if the MOSFET survived yet. Obviously the diode needs to react fast and handle avalanching energy well. Any suggestions? are some beefy schottky diodes suitable? Also, does making any ordinary diode go into that avalanche or zener reverse breakdown region cause it to potentially lock up and conduct for a period longer than the EMF spikes I'm dealing with? Or with any sort of hysteresis (like when using neon lamps)? Originally my wimpy glass 1N4148 diodes was wired in parallel directly across the MOSFET drain and source reverse biased. However, carefully examining this tesla coil schematic,it appears that there is both a forward biased diode in series with the MOSFETs, and another reverse biased diode(s) in parallel across the MOSFET & diode. It does not look like a bad idea given one the reverse biased diodes can shunt EMF spikes that are too large while the other isolates them from the MOSFET. My only concern is how lossy that would be at 12V operation.

Asked by -max- 2 years ago  |  last reply 2 years ago


A 15 volt Solar panel powering 12 volt dc bilge pump with no battery. How long will it stay working?

I did a little maker faire project to demonstrate how gravitational vortex power plants work. There was no electrical outlet available so I used a 15 watt solar panel to power a 12 volt 600 gallon per hour bilge pump to keep the demonstration running.  During the maker faire numerous people came between the sun and the panel and the thing stopped and restarted no problem.   I would guess that the bilge pump was running at half strength. (It has a 3 amp fuse so that would mean 36 watts is the max it can do?  An electrical engineer and a computer science student both said that I could probably leave the thing connected day and night and the low evening and morning current would not damage my bilge pump (or the solar panel).  It would just start up whenever the light got bright enough. Would anyone like to confirm that? Also, is there any arrangement with capacitors so that even the morning or evening sun will turn the thing (even if slowly) or is there a way to shunt that weak power to something useful (Like electrolysis of sea or  salty water to make bleach) and then go back to the bilge pump whenever the sun is powerful enough again? I would love to know because the project went really well and more could be done with it. Brian

Posted by gaiatechnician 6 years ago  |  last reply 3 years ago


Making a better spot welder....

I am in the process of building a proper spot welder from scratch. Proper more in terms of the electrical and electronics part but not so much in looks ;) My problem now is to find useful info on what power levels are required for certain tasks. I realise that welding thin sheet metal won't need as much time and amps as welding a 3mm stainless steel rod - but what is a "good" power level? I watched a bunch of Youtube videos showing various approaches but for many it seems the producer had no clue about the difference between creating a short with burn marks and a weld... Especially when it comes to creating battery packs with a capacitor bank as the main power provider you can clearly see the device burns holes but does not really create a welded spot. On the other hand there are a few videos showing spot welder made from a MOT that seem to produce a proper melted and welded connection. When I used a proper spot welder at work it had timing settings, power levels and even a feature to adjust how the current rises.... Not to mention a gauge that checks the pressure and only activates the welder once the set point is reached... There is a ton of info out there that after a thausand words still tells you nothing you need to know :( So is there anyone here who can shed some light on the actual process of spot welding in easy words for everyone to follow? I am aiming for a max output of around 400A @ 1.5 -2.5V with an adjustable shunt in the transformer core to avoid oversaturating the core. In a later stage I will add power control over the primary side but until then it is only time control, from a few ms to a max of 5sec if the damn controller arrives one day. Big questions: 1. Is a power control really required or is it possible to cater from thin to thick just by using different timing settings? 2. Since a MOT is used for the power supply: Is it better to leave the shunts out to fully avoid saturation by adding an inductor in line with the primary or is it still better to adjust the shunts under load to get the maximum power possible? 3. Aluminium and other materials benefit from using AC but would be good to have a DC output too, if so then what materials really need DC? 4. All I could find is that copper is used for the electrodes, due to resistance and heat transfer - are there other options apart from using copper? 5. Tricky one: I would prefer to use the secondary winding as the new primary to avoid core saturation and to lower the load on the power outlet. Where can I find very thin copper bar material that I can coil up and insulate as I would quite a few more turns to get at least 1.5V out of it? Just don't like the idea of spending days rolling a copper bar thin enough.... For the advanced model at a much later stage: Of course I would like to be able to use a proper power control instead of a motor dimmer or similar. For obvious reasons an inverter microwave jumps to mind. But after checking one I noticed one big problem: there are not really that many windings on the primary of the transformer at all! Same way our modern switchmode power supplies only use a few turns these things do exactly the same. After some quick and dirty initial tests I realised that even a single turn of thick wire already results in over 20V on the secondary. Wasted a lot of wire and time making one coil with 5 turns less and one with 10 turns less but the system would not even start with it. Seems these things need a fixed inductivity on the primary that matches the frequency used, in my case 36kHz. Would love to overcome this problem so I can at least go down to a single turn to get under 5V on the output side as space is non existing on these inverters. Can I cheat? Do I need to change the circuit to match the new primary coil? Am I thinking in the wrong direction altogether here? And added bonus would be to be able to adjust the power from around 15% to 100%, so far the electronics don't allow anything below 45%. Is it possible to drive these inverters in resonance? (Ok, off topic as I would like to use this for a beefy HV supply) Last thoughts: I know people already used Arduinos and Raspberries with displays and all but so far I have not found anything that shows how to do it properly. Seems all that counts is to create connection one way or the other and to call it a spot weld even if it is just a burn hole from discharging a capacitor bank through a needle like electrode.... For obvious reasons I don't want to create just another spot welder that makes a professional pee himself laughing about it. IMHO nothing beats personal experience with something but I don't really like wasting my time by trying what other people alread did a long time ago. So if YOU already built a MOT based spot welder and used for more than a few spots I would love to hear from you! Let me know what type you used, what problems or shortcomings you noticed or where you feel it just does not work out the way you expected it. From simple things like always getting bad sparks or arcing, over how easy or hard it is to get consistand results to whatever really annoys you while using your homemade spot welder. I hope that your feedback here will help me to write an Instructable on building a spot welder that does what you expect it to do, not once or twice, but everytime you use it. Mechanics might vary the same way the electrode style does but the weld should always be a proper weld that won't tear apart ;)

Posted by Downunder35m 1 year ago


PSU design (major revisions): Transformer calculations help?

Recently I have attempting to design a proper dual-rail power supply that will allow me to set a voltage as low as +-1V up to +-30V in 0.1V increments at (hopefully) 3 significant digits (at least for the lower voltage settings). Anyway, this supply is also going to be current limited to up to 5A,again, it can be set to just about anything. I plan on using an Arduino micro-controller to set the output. In order to do this, I plan on using the analogWrite functions, or better yet, a legit DAC. There will be 4 outputs from the Arduino that will set the power supply output by applying a 0-5V voltage on the input of the 2 current limits and 2 voltage sets. (one for the negative rail, one for the positive). However, I have kept running into the same problem: how do I plan on driving this linear power supply with up to 200W*? My first idea was to use a a MOT, due to their high-power capabilities, and re wind the secondary with the right number of turns to achieve this output. However, I have heard that these transformers are not optimal for continuous running due to their poor and cheap design. (losses are very high). My second idea was to search around for a 250VA transformer. However, even until now, the VA rating confuses me. How does VA compare to W? I know this has something to due with reactive power, real power, and apparent power. However, I have no intuition of any of these 'powers.' How would I go about calculating the correct size transformer for the job, also, I am going to assume this linear power supply has the properties of a resistive load, since it is rectified and smoothed with a filter capacitor, so practically nothing should react with the AC power. (unless there is something more to the full-bridge rectifier setup I am considering.) This is when I came across unwound toroidal cores found on eBay for $25, the perfect price range! However, this has raised more questions! to start off, beyond turns ratio, I do not know now many turns I need for the AC side of things. I know intuitively and from experience, mains-frequency transformers do not work with only one (or even few) winding(s). I think this has to do with saturation, but I'm no expert by any means. and the inductive reactance of the transformer's primary. How do I calculate losses, inductance, and other important parameters of a homemade transformer like this? Things get very nasty when I look back at rewinding an old transformer. Now I have all these questions about inductive reactance, power, currents, magnetic flux and saturation, but also, about determining the original power rating of something like a very old small welding transformer or one from a large 10A car-battery charger. Is it possible to approximate the power by measuring the dimensions of the core? How close will this approximation be?  After getting frustrated with this, I considered alternative approaches. What if I purchased 2 ~20V ~6A SMPS (switch mode power supplies) connected them in series, and connect the center tap of my linear supply to the joining point between the 2 SWPS's? Would this be unstable and be bad for the SMPS if a load was connected between the 'outputs' of this new center tapped supply? Would any sort of balancing be required? Also, a bigger problem includes how this will be connected to my linear PSU design. With a low voltage @ high currents, I would be wasting a LOT of power, power that has to be dissipated away from the transistors. This heat can approach 200W, which is company unreasonable! Anyway, I would them have to either a switching preregulator, or modify the SMPS's so the voltage can be controlled easily and varied between, say, 3V to 20V. absolute accuracy is not required, close enough, and rest of my PSU should handle it. This becomes seemingly impractical too, and many other considerations need to be made. What should I do? what are the calculations and factors I need to know? i do not have an LCR meter to measure inductance, so trial and error is out. Does anyone here have experience at this? Help would be greatly appreciated! *The 200W figure was calculated by taking 40V, (What I believe would be a safe to allow some slack for +-5V voltage drop across my 2 shunts and transistors) and multiplying it to 5A of current for the maximum power output. ------------------------------------------------------------------------------------------------------------------- I have added an image of my current design, and I have modularized it the best I could. The YELLOW is all my current power-management circuitry. Currently just a transformer with many taps, going to a currently-undesigned switch box that will change the voltage on the output, which is then rectified and enters a filtering capacitor, finally entering the circuit.  The GREEN field is the voltage set. It is the most major part of the PID feedback loop, along with the ORANGE field. It works simply by feeding a voltage to the positive of a op amp configured as a comparator, and with negative feedback from the output. It then outputs a signal to the transistor, turning it either more ON, or more OFF depending on how the output voltage compares to the +Vset. The negative portion is largely the same, but the input voltage needs to be inverted so the output voltage is set negative properly. I was not able to use less than 2 op amps for this portion, unfortunately. The ORANGE field is current set. It works by measuring the voltage drop across the shunt resistor, and outputting a unity voltage that is referenced to ground, instead of to the positive rail. (It took me forever to finalize and perfect that!!!) Anyway, this voltage is then fed into a op-amp configured as a comparator to drive the transistor. The BLUE field is my switching regulation topology, which is controlled by both the ORANGE and GREEN fields. Do you like my use of diodes as a super-simple voltage or current selection switch? the op amp that outputs a lower voltage is the one that gets 'listened to' by the transistors. This way, current and voltage mode enable properly. This does add a small problem when it comes to powering the op amps, all of them have to be powered off of slightly higher voltages to swing the full range due to the voltage drops of those diodes. In the PINK field is simply a single-transistor solution to a constant current load. This allows the regulator to be regulated even at very low voltage set levels. This is why I am able to achieve a +-0.5V on the output (at least within LTspice) Finally, and most unimportantly, the light PURPLE fields have a simple ultra high-gain difference amplifiers that will detect if the output current and current set are the same, and turn On or OFF the respective LEDs. The green LEDs are voltage-mode indicators, and the red LEDs are to show when current-limiting mode comes on.

Asked by -max- 4 years ago  |  last reply 4 years ago


Rewinding a MOT to make a high current supply. Answered

New Question: Ok, I've done a little more research on this, and it seems that MOTs are just pieces of junk basically. Manufacturers design them to go far into saturation because they don't care how much electrical power is wasted, as long as the transformer is cheap to make. The air gap is probably there just so it's easier to cool with a fan. Now I need to bring this thing out of saturation. There are about 90 turns on this primary, which I want to be the secondary at 30 V. So I would have to wind a new primary with 360 turns of thin wire. That's a lot of work, and a lot of wire. Is it worth it? The other option would be to add turns to the existing primary. This seems more reasonable, but just how much would I need to use to bring it out of saturation? Original Question: So, I'm a physicist (in training) and I know the theory behind transformers, but actual transformers are still pretty mysterious to me. I've found quite a few Instructables and other sites related to MOTs, specifically related to making high current power supplies with them. The problem I'm having is that even when the secondary is open, and indeed when the secondary has been completely removed (and the shunts removed), the primary draws upwards of 10A when connected to mains. To me, this is unacceptable. Transformers should draw significant power only when current is drawn from the secondary. I'm trying to figure out why (specifically) it does this. I've got a variac and the transformer only begins drawing more than about 2 amps once the variac is set to about 90V. This seems like non-ideal behavior to me, but what I know about saturation tells me that the amount of steel the core has is more than enough to stave off saturation at open secondary, but I could be wrong. The only thing I can think of is that the primary coil has about a 1cm air gap on either side of the core. Since the efficiency is related to the magnetic flux, and I'm guessing the area of the air gap is roughly 1/5 of the area of the core, this could cause significant inefficiency. Here's what I want: I want to make a ~30V (possibly with multiple taps) high current supply out of this MOT that draws less than 1 amp when the secondary is open. I tried connecting the mains to the secondary before I removed that and I got about 5 volts on the primary, but I need more than that, and the windings were so saturated with resin I had to just remove the entire secondary. I'm thinking about winding a new primary (using the old primary as the new secondary) with something like 18 gauge wire that would give me 30V. Would this work? What I really need to know is why the existing primary is drawing 10 amps. That's just ridiculous. If I can solve that then the problem is easy. Update: There is a difference between resistive and reactive current, and I know that reactive current actually draws net zero power because it's 90 degrees out of phase with the source voltage. Capacitive and inductive loads do this apparently. Is this the reason for the massive current draw? If so, I might be able to minimize the current draw from the mains line by putting a matched capacitor in parallel with the primary. But this wouldn't stop the transformer from heating up.

Asked by laserjocky 6 years ago  |  last reply 1 year ago


Magnetmotor - really impossible or just supressed?

When someone starts talking about a so called magnetmotor than most people judge right away.Laws of physics, perpetuum mobile is impossible, magnets are static....We all know the limitations nature puts on us... That however did not stop quite a few people since the 1950's to build working magnet motors. Or, to be precise: To make the claim, show them and then somehow disappear. A few though seem to have survived and even claim to make good business. Securely closed machine, stellite tracking and 24/7 online monitoring. Either just a bad and long running hoax or a real attempt to keep a secret secret. Even the somewhat famous Yildiz motor showed off around the world only to disappear.Some like them, some don't. Either way all this sounds like the perfect conspirary theory LOL So lets take a look on what is fake and what might be real but missing some vital clues. You can find several good Youtube channels created by people trying to build a working magnet motor. Some of them have no problems to admit failure and still keep trying and updating their projects. Did long enough and you see two outcomes. The first is giving up or "realising" that it will never work. The second often seems like a user is getting some relly good results and is really close to keep the magnetmotor running. Both disappear without and updates or traces. Now of course this is just confirmation that it will never work, but then again: What if it did already quite a few times? Even Tesla had patents for a magnetmotor and so far none of his patents were a hoax. Although none of his patents allow to actually build a working devices without some additional info and knowledge. And that is the key that I am trying to get: The lost knowledge.How can a magnetmotor never work? That one is quite simple from the start. If a linear model won't work no matter where you start then a rotary version will fail as well. And if a linear version works, it has to do so far at least 5 segments and with preferably increasing or at least constant speed. Having said that and assuming you know a little bit about magnetism: Ever wondered about shapes of magnets?? The common types are block, round like a bar and those disk like ones, some even with holes. A less well known version is the ring magnet. You can look them up as well as their corresponding magnetic field geometry - or what is assumed to be the right geometry. To give you a clue: All those floating spinning toys use a ring magnet in the base and onother one in the spinner. In the center is a dead zone for the magnetic field that is far lower than further out on the ring. And the strnger outer fields also reach further - giving the entire spinner a bowl like area to float on, the spinning just stabilises it like a gyroscope. A similar flat disk magnet wouldn't have this indentation in the field but rather a dome like sphere. The ring just kicks a dint into this sphere if you don't mind the simpification. Similar changes in the field structure happen when you combine two or more magnets. One example we all know is stacking identical smaller magnets. And often we are suprised how much stronger two thin disk magnets are compared to a single. Distance however sets a certain limit. And take those hook magnets... Just a small ring magnet in a metal pot with core. Remove the magnet and just by itself it is far weaker. Why? Quite simple.... The same way a transformer core directs the magnetic flow, the metal part of the hook magnet provides a shortcut for the magnetic field - and in return all is much stronger ;) Now you have some more clues, but still there are tons of options for failure... The most common is the sticking effect. No matter how well you planned and designed in most cases you linear or rotary prototype will stall sooner or later. Even if started manually at high speeds some seem to run very long but once they slow down and stop it is obvious they always stop where the magnetic field won't allow the binding effect to be overcome.Wouldn't dare to say that I have a working magnetmotor, but I might have some clues you want to try if you decide to give it a try yourself. So how COULD a magnetmotor actually work? Like in the Perendiv examples all over the web, you could aloow a moving responder to the rotor. Like a piston the responder will be lifted in areas it would otherwise limit or reduce the speed of the system. Well designed only a few mm would b required but it also means wasted energy to move the responder. Then there is the nice way of modifying fields by adding magnets in different angles and polarities. Lets say towards the end of your stages on the linear model it is hard to overcome the binding effect from the end of the previous stage. The perendiv model would now somehow change the distances. But you can also add magnets to lower the binding effect ;) Like a ring or hook magnet you can shape the field and offer a stronger repulsin field or a lower binding force. Last but certainly not least is the option of adding magnetic metals like iron or somehow weirder ones like bismuth. So, do we have any examples of something very common utilising any of this? We sure do :) Take a speaker apart and you end with the cage, the membrane, the actual work coil and the magnet. We don't need anything but the magnet so take a good and very close look. What in the audio world is called a shield to prevent the magnet from messing with things close by is exactly the same as on a hook magnet ;) Only difference is the tiny gap for the coil. The magnetic field is directed into two paths, one by the metal core, the other by the inner enclosure of the magnet or the magnet itself. The coil operates in the area of maximum flux.Last hints... If you take two identical and strong magnets with north or south facing up then it is quite hard to push them very close together. But check what happens if you try the same wen both soth poles (or both north poles) are placed on a magnetic surface - if in doubt your standard fridge door. Suddenly you can move much closer together with the same amout of force (not considering the added friction!). And similar story for opposing configurations. Where in free air or on a table the magnets would just jump together, on a metal plated you can move them much, much closer before this happens. Copper pipe and magnet fun :) Ideally you would have a straight copper pipe and a cylindrical magnet that has a loose fit in the pipe. Aluminium pipe work too or even a roll of aluminium foil if you have nothing else. A magnet in the pipe will travel very slow down the pipe, friction is not an issue here. So what is slowing it down? The magnet creates a field in the pipe and through that the pipe generates electicity. And funny enough this electricity creates an opposing magnetic field in the pipe - the magnet slows down. Even if you glue it onto a wooden stick it won't rush through it. Trying to push it by hand and you feel the created resistance. The faster you push, the harder it is to push! If you made it all the way down here with the reading then I have to assume you fit into one of three of my categories. a) You are a total sceptic and just read it for your amusement. If so, then please don't post a reply with usual negative feedback, instead see it as the same fun you had reading it ;) b) You are at least curious and like to play with magnets. In this case take the above as inspiration to explore more ways to have fun with your magnets! c) You are more or less frustated because you wasted a lot of time and some money to build a magnet motor that just won't work. A and B might go on and enjoy the fun, C however might want to read very attentive now ;) If you take some indicator sheet for magnetic fields, like these funny green ones, and play with moving magnets then you see a very interesting effect on the "screen". The otherwise static field lines change chape and sometimes even seem to disappear or shrink. With a small rotor assembly it almost looks like flashes when the magnets move past each other. This effect is often totally neglected and to be honest I overlooked it for a long time as well. Being able to see how the magnetic field changes gives the thing an whole new dimension so to speak. Creating a magnet with a complex shape is difficult to say the least. Only ferrite or ceramic ones can be used and you would cut of machine them according to your desired shape and with regards to the orginal center of the magnetic field. So most people revert to the classic way of shaping by adding magnets of various types, sizes and amounts. Modern neodymium magnets make this trial and error process easier as there are many sizes and strengths available. Add a detector shield of suitable size and you have hours of fun time ahead of you. But doing so in any rotary assembly is next to impossible. So what did Yildiz differently and what was missed so many times? Yildiz took it a step further and not only provided "shunts" to create very strong magnetic field from the generated electricity but also a second rotor. Since we all start small lets focus on the basics first. Remember the hook magnet and speaker or the copper pipe? Some examples for shape shifting your otherwise static magnetic fields: 1. A magnetic metal "connection" from one (low in the armature) pole to an opposing (high in the amature) pole with cause the field from the "high" pole to "bend" towards the connected magnet. 2. A magnet with an orientation of 90° to the last magnet is the sequence will severely influence the field of this last magnet! This goes for either orientations! 3. Adding a non-magnetic "shield" around a magnet, like a piece of copper pipe, will not affect the static field of the magnet. However it will severely alter the field of the enclosed magnet when another magnet passes it! It will also affect the overal field during the passing as the moving magnet will also induce a field in the copper by affecting the field of the enclosed magnet! Thickness and lenght of the shield influence the strength of these effects. 4. In a simple perendiv motor design the bar that creates the attraction for the spinning part is a magnet too. Either a long bar type or two small ones with an iron or nickel rod between them. There is no need for a piston or something that drives the bar up or out of the way ;) Just use the right magnet at the right spot on your rotor to repell the bar ;) Mount the ar with suitable springs and you suddenly can have multiple stages on your rotor instead of just the usual one! Don't forget the moving magnet on the opposing side of the segment in question though as otherwise you still will get stuck. (Hint: You can place a small but powerful magnet in the center of the opposing bar ;) Just make sure you limit the springs movement so the bar won't be pulled closer)Ok, hold on now! Does a magnet motor actually work or not? I can only give hints and say the laws of physics as we know them apply to magnetmotors the same way as everything else. Unlimeted motion without supplying energy is not possible. Limited motion with adding or using energy however is still possible and real. The same is true for being able to machine, 3D print or otherwise manufacture at very tight tolerence and accuracy levels. This includes bearings or bearing systems with very little friction losses. Just check these floting and rotating magnet toys that look like a spindle. Only a tiny needle like pin makes contact with a glass surface - next to no friction loss. A proper and supposedly working magnet motor should provide more energy than what it uses - one way or the other. No law of physics lets us get around the fact that such a motor could only keep spinning if the produced power or motion energy is at least the same as what is required to make it move. Magnets lose their strenght over time, they are like a very slowly depleting battery. So, isn't it funny that all magnet motors so far that claimed to work also had the requirement to replace the magnets once the things fails to work or start? And if you leave a very strong neodymium magnet shielded from outside fields or magnetic stuff than your grandkids will still find a quite strong magnet. Do a little performance test with your new magnets, like how much force is required is required to lift them off a steel plate. Make the same test with the magnets once you played around extensively with them in your motor. Now take a spare magnet that was never used from the orginal batch and compare both against each other ;) If the motor would not use energy then why are the magnets depleted to a certain degree, realted to runtime and usage time? Wait a minute! Does that now mean it actually works? Lets just say energy is certainly used. We only know similar effects from electromagnetic systems. But did anyone ever really check how much actual energy is in magnetic field generated by a non electric magnet? Get a good sized N52 neodymium magnet and check how much force is required to pull it off a steel surface. Now try to get the smallest sized electromagnet capable of that force and check how much energy it consumes at the level that equals the pulling force of the N52 magnet ;) Makes no sense to even try to compare these you will say now. I just say energy is energy and we were formed to only think in certain ways and don't even try silly things like this ;) To keep the fun up let us imagine we would actually have a similar energy available than what our electro magnet would require. In reality more because we wouldn't have electrical or flux related losses in the metal around the coil. Or is the imagined reality, no clue ;) If true it would mean even a motor with very bad efficiency would be able to create huge amounts of torque. Well, torque is basically acceleration. Which would mean our motor would not just be happy to spin, it would speed up until the bearing fail or the thing is ripped apart. Imagine a dental drill of that size and weight suddenly falling apart at full speed... Every example of motors claimed to be working, that are not fakes, seem to be happy no matter what the load is. It the thing turns a generator than it would have to slow down a bit with the increased load but they don't. With no limited factors otherwise this makes them a fake. Even a perfect motor would have to react to load changes.... Don't we agree that the stronger the magnetic force or field in a conductor the stronger the resulting magnetic and opposing field of the conductor? We use the difference to either drive a motor or take out electricity... But if you take the "open" shielding of a magnet in a changing field than the influence of the shield on the overall field gets stronger with stronger field changes. And properly desinged and orientated they would actually double as a natural limiter for the rotation speed. Once the electrical energy in the shield becomes too strong it will be able to cancel out the field of the enclosed magnet...If we assume a magnet motor is really possible and works with the intended output to keep it spinning or even take energy out: Then what would be possible downfalls that stop this thing happening in everyones garage? We can explore the stars but so far no one bothered to invent anything to visualise magnetic field in a 3 dimensional way other than by simulation. No realtime and true observation like this. The few working technologies that exist rely on sensors, interpretaion and filling in gaps. But imagine something like a detector shield as cloud! And then even better with selctive spacing to get a realtime view of where exactly the field lines go. All we can do is forget our teaching and try it out anyway ;) If by some mistake a magnet motor would really work right away, then chances are high the inventor would wonder why that thing takes off like mad and how to stop it. Unless well prepared it would certainly end in the destrution of the motor. But the inventor would know what to look for in the next prototype. The logical conclusion would be to the couple the energy taken to the speed while physically limittin the free load speed. The other one would be the design the electrical generator around the and within the motor. To even get close to this point you would have to spend endless days and nights working on finding a solution. The closer you get the more disappointment when the final model still fails to keep spinning for more than a few hours. Most people will then accept defeat and move on... Still not saying it actually works but if you made it to this point in time where it could be easier to move on and do other things:Ever wondered what would happen if you "shield" a magnet with a coil? Of course nothing would happen as we know. But try this in some fixed assembly that allows you move another magnet through the field of the shielded one. Perferably witha force gauge or some option to read out the energy required to move it through the various stages of the field. See what happens if you short the coil or add a resistor to it ;) Now if this coild is able to produce electricity then the more we use the more the effects on the required force would change. What do you think would happen if you combine common coil relations of electric motors to a "coil shielded" magnet motor? Right, all these coils would interact with the magnetic fields of the coils they are connected to... And through that with the overall field surrounding the enclosed magnet..... I leave up to you to imagine how these interacting coils could provide "resistance" or "acceleration"/"surplus electricity"...Like they say: You can only find out if you try ;) To keep up the positive thinking: A permanent magnet just sticks to any magnetic surface and does so with the same force. But the real energy loss in terms of getting weaker can almost be neglected. Any electromagnet capable of the same holding force woul require ongoing energy supplies to keep it up. It is using energy the same way the permanent magnet does! The difference is the permanent magnet is not seen as anything that would provide us with energy.... And if it can't provide energy other than passing through coils then why the heck does it keep sticking to the fridge year after year? It does require energy to keep this weight up doesn't it, even if you add a thin teflon disk and oil to reduce friction? ;) No magic, no "free energy" bogus, just plain physics viewed from a slightly different angle than what we learn in school ;) Have a good laugh and a good beer, then read it again and just consider some of the things here that are not mentioned in any literature about magnetism that we commonly use. Now I got you thinking, didn't I ? ;)

Posted by Downunder35m 2 days ago


Ceiling fan generator mod to the max

I stubled upon several mods to convert a standard ceiling fan into a more or less usefull generator.So if you are looking to go this route then I might have some nice improvements that can be implemented.People like these mods for some weird reason, despite the fact that it requires quite a bit of extra work to make them weather proof.However, when it comes to the fundamentals then to me it looks like some folks out there are missing out.On the available power that is...Always the first step for a mod like this is to replace the induction ring with a lot of magnets.Second step usually is to remove a lot of the coils, especially the inner ring.Now, these two stator designs are common for fans with two speeds.Those with three or even reverse might have a different configuration!Lets start on the magnet part:The recommended way of placing the magnets is by creating an air gap as small as possible - makes sense.But then it is always the same amount of magnets as there is coils - and the spacing is also the same as for the coils.In the general generaotr design world this configuration is prefered as it allows for the best performance.If you dare to go a bit further and cosider how the magnets react to the stator configuration then you might want to consider a different option.You see, these two sets of coils for two different speeds mean just one thing:A different amount of poles is created, with the outer ring having more poles than the inner ring of coils.The core is split around the coils, not just to allow the windings to be made but also to provide independent paths for the magnetic field - resulting in the two pole configurations.Amounts differ by diameter, power level, manufacturer and so on.What is always the same is that the inner ring has less coils and that the outer segments of the poles created have even spacings.In the normal mods you see posted these gaps in the core for the outer ring are closed by inserting lamitaed pieces from some old transformer.And you end up with ONE usable coil configuration and ONE power output.The slightly advanced mod uses the inner coil to add some load depending on the speed to prevent spinning out of control in high winds.If you try a normal DC motor with permanent magnets than you will notice the strong binding forces, it is like the rotor sticks in certain places.The better ones use and uneven configuration to reduce this binding effect ;)In my mod the magnets are selected in size to almost be the same length as two stator poles next to each other.This allows for the best induction while still allowing "to experiment".Bringing the magnets and the coils into play...As said an exact match of the number of magnets to either coil ring is not ideal.The prefered option is to go somewhere in between.For example:Outer ring has 18 coils then the inner ring will have 9 coils - exactly half.360° divided by 15 make a nice 24 degress per magnet.But with 12 magnets you get an even 30°, which is far easier to deal with.16 magnets at 22.5° is another option.So, what does that exactly do for us?The bad thing is we get slightly less performance if you only see the standard mod with one coil ring.The good thing we get far lower binding forces and through that the thing will even spin in very light winds.Adding both coil rings with a suitable rectifier however results in a pulsing output of two sine waves.With just the rectifier we get a ripple that is easier to deal with through a capacitor.The extra power available is in the range of about 40% and make more than up for the "reduced" amount of magnets.Going the extra mile once more ;)Having created a much fancier ceiling fan mod now you might wonder if there is not a way to get even more out of it.And there is.For example by utilising a gear system or belt to get a far higher rotational speed on the generator than what the blades would provide, prefably then with quite big blades too and an automatic break for high wind conditions.With the reduced binding forces the generator will be happy to spin at quite high speeds in low winds.Downside is that you will need to build a far more sturdy bearing housing.In return though you get more stability and durability.You can do the math yourself based on the number of poles per ring and magnets to get the output frequency based on the RPM's.Perfect would now be to use a switch mode power supply configuration to directly transform the provided output into a stable DC per ring.And yes, it is possible to use mechanical systems to provide a fixed output speed from the blades to the generator - but way to complex and lossy!Lets do some lame math with no regards to realities:If the original fan would spin at 100 RPM at full speed than we could say our generator should provide the mains voltage at about 100 RPM.Keep in mind we utilise both coil rings and not just the high speed one!Geared and with the blades spinning at 100 RPM we might get as much as 1000V from this little generator....And even with the lower amount of magnets we migh see frequencies above the 500Hz range.The good thing now is that normal iron core transformers can still operate at these frequencies.A bit lossy in the upper range but acceptable for the purpose.Put simple: A 10 or 20:1 transformer per coil ring would provide us with a far more suitable output voltage and much higher amps.If you made it to here than you certainly wonder about other magnet configurations.Checking the stator configuration you will by now realise why I selected the magnet lenght accordingly.The magnets "activate" one coil after the other.The spacing between them means there is always some overlap where the magnets only cover one half of the stator for a coil.This is ok because we don't really have to worry about the resulting messy output.Ideally though you would want to have a magnet activate both coils, the inner and the outer at the same time.What we did though was to make sure that at no time more than ONE magnet fully covers more than ONE coil!It is the best option to cover both coil sets while minimising binding effects and increasing the avialable output.To go the last step you would need to invest a lot of time re-winding all coils :(You don't want to do this unless you have the means and no friends and family that might miss you for a few days....I found a far simpler way to change the coil configuration, although it is not as good a re-winding.So let's go full scale shall we?Ceiling fan reconfiguration!If you take the usual 18 to 9 configuration than one thing jumps to mind reight away: 3-phase power!Cutting the wire that goes from coil to coil might not always be possible and if it is then you need to know how to handle it.Magnet wire can be hard to solder.Burning the coating off results in corroded copper that is even harder to solder.If you are lucky though than a reall hot soldering irong will be able to melt the coating.The flux from the solder will start to cover the wire from the cut and the solder will follow.If not then using some fine sandpaper and time is the other option to remove the coating...Ok, you seperated all coil and have two wire ends per coil?I hope you did not cut off the ones going out to the actual connections to the outside world ;)Properly solder each wire end and take your time to check it is really proper and not just a few spots.Mark or number the coils on the rings!For the inner ring we have 9 but need only 3, so we start at one connection to the outside world and check if this connection is on the outside or inside of the coil.For this example I assume you picked the one that goes to the outside of the coil.Connect the inside wire to the outside wire of coil number 3, assuming we start with 1 here ;)From the inside wire of 3 you go to outside of 6 and the inside is you first new output connection.Do the same with the remaining 6 coils and where needed add the required output wire.It really helps to have wires with three different colors here, one color per new coil set.Note which color corresponds to to the three coils used!!!The outer ring with 18 coils is sightly different here.You see, we want a "flowing" magnetic field that makes best use of the new coil configuration!We can not simply bridge them in any way we feel like without considering how this might affect the electrical side of things.As we now take the approach of a three phase system it makes sense to use a more suitable magnet configuration as well.So before go to the outer ring of coils lets have a look of the best option for the magnets first:The stator packs are evenly spaced in our example and will alow us to use 18 magnets.This provides the best performance with the downside of a higher binding effect, but we need this configuration to get the best possible output.As said at the start I selected magnets that are just shy of being the same length as the corresponding stator segments.In a "free" setup these magnets would now be quite hard to place in a makeshift ring.Even harder in the original casing.A 3D printer certainly helps but some common sense too ;)Wood is easy to work with and if you select the right stuff than making a suitable ring to hold your magnets and attach to the drive system metal parts is not too hard.Bar or brick type magnets can be quite easy be utilised on a wood setup :)The key is that you add Flux Capacitors - sorry couldn't help the reference to Marty....What I mean is to add some magnetic material between the north pole of one magnet and the south pole of the other.Lets say your magnets are 15mm long and have a spacing of 5mm.Then a little plate of 12mm would be next to perfect.This plate needs to connect the magnets on the backside, the side facing away from the coils.Use a dremel tool or what you have to first create slots for the metal strips or bars, then the same for the magnets.Glue in the metal first and once set add the magnet, making sure the always go north to south with their alignment.Ok, and what does this do for us?I hope you are not one of these persons who starts building while reading...What we created now is a shortcut for the magnetic forces.The field between the magnets is severly compromised in terms of being usable for the coils.We do get a much soother run though...I only did that to have some fun and check if you paid attention - sorry :(What we really want is an effect similar to what you see on a loadspeaker magnet that is still in its metal shielding.A ring magnet with one pole on the inside and one on the outside is used here.The shielding provides a path for the magnetic field that is not going through the speaker coil - hence the little air gap for the coil.If we do the same then our efficiency will be going up quite a bit.Take two identical steel parts, like some butter knifes, and prefarbly a force gauge.If you try to pull your magnet at a 90° angle from the blade you will get a certain reading for the required force to lift it off.Most people now think that this would be the max a magnet can hold.So take the other knife and place the magnet between them.If you pull the knife off with the gauge now the reading will be higher than what you get from just the magnet ;)Taking that to our model and keeping the field lines in mind we now know that we could even use slightly longer plates if our magnets happen to be a bit short :)Just place them right behind each magnet !Back to the outer ring of coils....With 18 magnets we get an even system for both coil rings.However we want to make sure that our output waves are syncronised and not at random order.We need to combine two coils to be back on a 9 coil configuration as on the inner ring.The other option is to provide two sets of outputs for outer ring, resulting in 3 3-phase outputs.Both have their pros and cons....But if you check the 18 magnet configuration ina ction over the coils it becomes clear that combining two coils the usual way is possible but also that our inner ring does not get a proper north south action from the magnets!Only the outer coil ring works properly!For the inner ring we never get only a north south combo, instead a lot of mixes.Did I mention to read first? ;)Of course we can only use 9 magnets in our configuration, but at least I did not traick you on their size....You see, we need to account for the fact that the coils are not just evenly spaced but also that all configurations in terms of coils to stator pack are doubles or halfs.Makes a lot more sense if you know how these asyncronous motors work :)With 9 magnets we actually get both inner and outer ring coils activated properly.Plus we now have the benefit that there are always twoouter coils in sync with each other.Means apart from the same way you wired the inner ring you make this addition to the outer ring:"One" outer coil is created by going from one coilinner connection to the outer connection of the second after this, skipping one coil.The resulting output is again just 3 phases but with double the output voltage.The key is to again take notes of how you connect and wire the coils - and the colors used for the output wires!Let me give you an example for the correct order:I we take the number 1 coil on the inner ring then coils number 1 and 18 would be next to it on the outer ring.You want to combine 1 and 3, 2 and 4, 5 and 7,....And you want the resulting three coil packs and wires colores to correspond to the inner coils in the same order!That is true for the always same way of combining coils from the inner to outer connection - or the other way around but never mixed!Ok, we have done the magnets and the coil configuration now properly, no jokes this time!With two simple 3-phase rectifiers we get two DC outputs that can be combined or used seperately.As we end up with roughly double the output voltage on one output but all coils are the same it makes sense to treat them independly.For those who wonder why:If you add a load than one coil system would take a higher loading of it.Meaning while one coil set is stll fine the other will already start to overheat - if the load is too great.So we use two rectifiers with some filtering.In the basic form just a really big electrolytic capacitor of suitable voltage or a full LC filer system with multiple stages.Either way we can now utilise some better DC-DC converters to get going.Considering the equal max watss the coil rings can handle it make sense to include some current limiting.A good converter will provide this option.Both converters can now set to the desiered output or with some added protection diodes and adjusted properly to the same voltage combined for just one DC output.Compared to the standard mod of removing coils and bridgning stator packs the resulting output power in overall Watt will now be about 40-60% higher - depending on the model and quality of parts.Special words of wisdom:Consider the orignal max speed of the fan when used as intendet - see this as a theoretical max output that equals your mains voltage.Just ignore losses and such things - better to be safe than sorry.It becomes clear that it quite possible that your output will be far higher than mains voltage and that you need use transformers for the two 3-phase systems so you can use standard DC-DC converters, which have a max input voltage of around 50V only.This means your converter must be able to handle the higher amps!The fan might have only used 100W or less than 500mA but at high speeds and a ratios of lets say 10 to 1 for the gearing high wind speeds might get it up to over 5 amps on the transformer outputs.Please do the math first for your gear system in relation to the max wind speeds you want to use with your blades!If in doubt use a converter that has some reserves to offer, especially if you aim to charge batteries as quickly as possible.The most vital part however is to ensure that all previously cut wires are isulated properly!!!Magnet wire of the standard kind is good for about 1000V max, so don't drive it higher!Heat shrink with a hot glue liner is prefered but hard to apply in these thight spaces.Since nothing moves consider using long enough wires for your connections so you have enough space to solder without affecting the heat shrink tubes.Liquid insulation or rubber is the last option and should only be used to finalside the heat shrink security measures.Best option once all is confirmed to be working fine would be to make a custom mold and to fully enclose the staotr pack and wires with casting resin or an insulating casting mix.Make sure to keep the output wirese free at the their ends ;)What if I don't want to build a complicated three phase rectifier and just use a single phase system as it was?Firstly chances are your coils are already connected in a three phase configuration, just all in series.But working out a suitable magnet configuration to suit this is much harder if you want to use both sets of coils.In a series configuration like the original you also have to accept the losses from these connected coils.The higher the overall resistance the lower the possible output ;)Main problem however is to get the magnet working properly.The standard 9 or here even 18 magnet configurations still works, especially with the added shielding from behind.But the coils also produce a magnetic field, which grows with the load.Means that an top of all you also have the coils working against the magnets and create even higher losses.Explains why the simple folks prefer not use the inner coil set if they go with a single phase system.So either accept the losses and just use the outer coils or do it fully and get far mor output.And by the way: a 3-phase rectifier modlue is only a few cents more than a standard bridge rectifier ;)Ok, and why do I bother to write all this?People like to tinker but most don't really invent.Following some simple instructions is easy, trying to work it yourself much harder.The reward however is that you actually start to know what you are doing :)And what works for a ceiling fan can be used for these ring style washing machine motors too ;)Anyways...We need to get back our roots.Start thinking for ourself again, work things out instead of just looking them up.If people would be aware that a simple ceiling fan could provide about 3 times the output power of its rated installation value instead of only just about half......Super strong magnets allow real output even without re.winding all coils.And what works here works for other things too.We only learned to use magnets in a striaght way because we can not bend them.But we can bed the magnetic field lines to our advantage!The simple shielding used in this mod is nothing more than a shortcut to enhance the field strenght where it is is needed.By a simple coil modification we basically bet two electrical generators for the price and size of one.Apart from stating how easy it would be to place multiple stators and magnet rings into one generator the magnets itself also allow for even more output.If you ever played with hook magnets or speaker magnets then you know how much stronger they are compared to just the magnet once they seperate after hours of fun for you.Imagine you would replace the single bar magnet with two block magnets that are joined by a magnetic shunt like out simple shielding before.If the magnet blocks now would have a slightly smaller footprint than your individual poles:Imagine you create a hlaf ring shaped magnetic connection between the two blocks that also goes aruond the outer perimeter up to the outside of the magnets surface?I mean the surface facing the stator poles?Damn your imagination is good, yout it right away!Of course we would then have a magnet that allpies its full strength focussed onto each pole of a coil!And of course the resulting field would be far stronger than just using the magnet blocks itself and still significantly higher than just adding a shielding or connection between them.The affect of the next coil coming is also drastically reduced, which in return also increases the efficiency.In terms of numbers:If a fixed neodymium magnet would provide us 100$ field strength as the base point with no shielding (just the magnet blocks alone);A fully shielded and connected system, like in a hook magnet combined with a U-style magnet, would reach above 400% here.....Adding witchcraft to the mix ;)Although I know better I just assume some of you have now a working double-three-phase-ceiling-fan-generator.And that would mean you also have some fans to spare from your long experiments.Modern ignition coils seem to have nothing in common with our ceiling fan or resulting generator.So why do I try to use them anyway?For the ignition only one polarity is prefered so the spark works and travels as intendet.Means the "wasted" energy from the othe half of the pulse seems to be lost.The electronics do a lot here but magnets too ;)The core of the coil has magents at either end, turning it into one long magnet that still has the right properties to act as high voltage transformer system with the coils.The coil appear to be pre-loaded and with the ignition pulse it has to overcome the magnetic field pre-set by the magnets.And when the electrical impulse is off the same magnets also accelerated and increase the resulting fall back impulse - which provides the spark.Unless you have a suitable laser cutter or simlar cutting tech available somehow it will be hard to modify the metal plates of the stator.But if you could...Imagine you could add magnet inside the plates that are inside a coil.The same pre-loading would happen.Does not really help in terms of adding outpur as our rectifier would suffer badly here.It does give ideas though...Shielding works fine for the magnets, same for field shaping.Electromagnets use the same techniques...So why not use some leftlever transformer cores to add more "shortcuts" for the coils?Strips of transformer core sheets added either side of the coils increase their field strenght and result in better output!Three packs either side of the stator pack are usually no problem.Now take your leftovers and do a standard mod.Compare the max output on the same windmill with what you get from my mod(s).The only real magic I used here is that I actually bothered to combine multiple and already used methods to drastically increase the available output of an otherwise utterly useless generator mod ;)Warnings:If you take the above mods serious and to the their extreme than it is imperative to make sure you have safety measures in place!Assume the lowest rating for the magnet wire and if in doubt stick with a max output voltage of 800V.These mods are potentially lethal if you don't follow what is common sense to everyone dealing with high voltages for a living!Most people will start without any gearing or belts and use the wind directly.Even here it is easy to get far higher RPM than what the thing ever did under your ceiling.Without some fixes you will need transformers to reduce the output voltage accordingly.Only other option is to limit the max speed to what your DC-DC converter can handle.Making mistakes with mangets can cost you a lot of time and work, make sure to mark their poles somehow to prevent putting them in wrong.If in doubt then double check!Always keep in mind what the magnet wires and your connections can handle!You don't want any arcs or overheating.Some added electronics to monitor wind speed, rpm's, load and temperature of the coils can turn out vital once you upscale.Before letting your new generator do its thing make sure you tested all to the max!Use a drill or so to speed it up and check the limit regulation for the converters.Measure the actual volts and amps going through your coil sets at assumed max speed and max load.Monitor the coil temp while doing so to ensure nothing is out of limit!You are kidding me here right?A scrap ceiling fan shall provide more output as a wind generator than what was used to spin it as a fan?And of course I need not one but two 3-phse transformers...Pretty clear it is all a fake because nobody could replicate any of it unless limited to what the converters can handle...Didn't I say to think outside normal restraints already?A single phase transformer uses two coils in the most basic configuration.For example one side for 240V and te other for 12V.But some of them are more efficient than other ;)A 3-phase transformer uses 6 coils, two for each phase.And there are plenty of standrad transformer cores out there that would allow us to use this configuration.The worst being the MOT, or microwave oven transformer.Very lossy for a reason but good as an example as these have three core stems ;)Now that you see that you will that a lot more transformers actually allow you to replace the two coils with 6 ;)Ok, but why not use a rectifier first and not use a transformer or two at all?The resulting output voltage will without a gear REDUCTION be much higher than what a cheap DC-DC converter can handle.And at such speeds the effiency would be very bad too.You would need huge capacitors of good quality to deal with the now more impulse like output.And considering the primary side of the transformer does not require anything thicker than the wire on the coils of the fan...Not hard at all to find some suitable tansformers to salvage - or to use some nice ring transformers ;)No kidding around, just facts and possible options you might want to explore.Does that now mean I get free energy?Sure, if you mean you get the free nergy from the energy of the wind at no cost.No if you think a ceiling fan could ever power your house.Internal resistance, size and wire/connection properties set our limits.Not to mention that they are designed to be dirt cheap.If you are in a windy region and assume a realistic 300W minimum output from a 100W fan then adding more stage multiplies this.These fancy upright windmills are not just powerful but also would allow to use one modded fan either end.If big enough and with enough wind force throughout the year you could just add a second or third stage to ech end.With 3 on both ends the resulting output would then be suddenly 1.8kW per windmill....And all from scrap parts with only the costs for the magnets...No wind? Then use water....None of it? Get some greyhounds and build a big hamster wheel :)You get the general idea I hope...

Posted by Downunder35m 10 hours ago