High Voltage Amplifier

I am trying to build a high voltage amplifier that will amplify an AC signal of approx. +-5V to a signal of approx +-100V.  I was looking into building a common-source amp using JFETs or a common-emitter amp using BJTs, but both seem to have an output waveform of 0V to +100V.  Is there a way to modify these amps to have an output waveform of -100V to +100V?   Also, if anyone has any better Ideas, please let me know. Mark

Topic by questionmark05 

Voltages for 7AH, SLA batteries

So I've read all on the web about the voltages of a lead acid battery, and according to sites like This One the battery should be full at 12.69v or so. The only thing is I'm getting 13.02v on one SLA, and 13.08v on another. One of the batteries is brand new, and the other is out of a UPS. Are these batteries badly overcharged, or am I just really ignorant and can't find a simple site listing SLA voltages :) The batteries were not connected to anything for about 12 hours before I took the readings, and I have tested the multimeter I used, and it is accurate.If it helps, the battery says:Constant voltage charge(25C)- Cycle use: 14.5-14.9V- Standby use: 13.6-13.8V- Initial current: 2.1AAny advice / help would be greatly appreciated!PS) The main project is powering a computer with these batteries. I've done that so far and it draws only around 1.8A, so hopefully it could last for quite long! (~5 hours or so)

Topic by cb22   |  last reply

Low voltage health problems

Hello, I saw a great project on youtube, a water button, and gave it a try. it works, all it does is when one touches water, a led turns on, just a proof of concept. But what I was worried about, is if there are any negative health impacts of 3.3 v going though you and into the ground? The power is not noticeable, but still, I worry. ps. I did Google this, but couldn't find anything.

Topic by penguins   |  last reply

How to make Voltage regulators

I would like to know how to make a voltage regulator for an old generator. The regulator has stopped working and is hard to replace. I need an out´put of 120 volts with 15000 watts and ofcourse the 50-60 hertz. Thanx for your time

Question by Soochi   |  last reply

step down voltage with a resistor?

Hey i used a 1 mega ohm resistor instead of transformer before bridge recifier and it works the led glow but the glow of led is very much less why???

Question by taylorsane 

Over voltage protection circuit

Hi everyone! So i was making one of those water level indicator circuit: https://www.instructables.com/id/Water-Level-Indicator-with-Alarm/ I found the construction to be fairly easy for a newbie for me. I modified the circuit according to my needs, and have successfully constructed it. There is a small issue though. The place i live is susceptible to over voltages often and our fuse system is presently out, so my family has discouraged me from implementing the circuit at home in my main water tank. They want me to add a over voltage protection circuit so that they can feel safe. So anyone has any idea on how to construct an overload protection circuit(The circuit should be simple and understandable for a newbie like me)? My supply mains are 230v AC. It can either be before or after the transformer stage.

Topic by charmquark   |  last reply

current or voltage for rail gun?

Hello i've ben wanting to make a powerful rail gun. I have ben checking out capacitors but don't know which one to buy. what my main question is, should i get a high capacitor with high voltage discharges? or should i get a high voltage capacitor? will this capacitor work? (http://nl.rs-online.com/web/p/products/7637858/?cm_mmc=NL-PPC-_-google-_-3_NL_NL_M_IP_and_E_Exact-_-cooper_bussmann%7Celectric_double_layer_capacitors&mkwid;=sagNlIMw4_dc%7Cpcrid%7C90954405920%7Cpkw%7Cxv3560+2r7407+r%7Cpmt%7Ce%7Cprd%7C&gclid;=CjwKEAiAoOvEBRDD25uyu9Lg9ycSJAD0cnByHZD584cPkCSCgOnFENsjk4lnghmHy3XmwBKaYeWquhoCukvw_wcB) and is current more important than volts in a rail gun? thanks. sorry for my bad english.

Question by LorenzoD38   |  last reply

6v to 12v system?

I have a 1929 model t that is curently a 6v system with no starter or generator. I would like to use a starter generator off of a modern galf car. Is there any way i can step the voltege down befor the battery or would it just be easyer to add a converter in to run the original lights and ignition system? Any help would be awsome!!!

Question by theoldway   |  last reply

How to lower the DC voltage of a transformer. Answered

Hi, at last i have got a 45-0-45 transformer @5amps, but now i have a problem, the VDC output i am getting is 74vdc but my 400watt rms mono amp's maximum input VDC is 56vdc, so i don't think its a good idea to feed the 74vdc, so is there a way to lower the 74vdc, BTW please don't advice me to unwind the secondary coil because i am new to electronics and the transformer didn't come cheap, so i don't want to break it. i am using IN4007 diode and 4700uF 63V cap for the bridge rectifier. ​I just forgot to give some details on this topic. The transformer is to use with the 400watt rms mono amp. The amp has 8 MOSFETS side by side, 4 IRFP9240 and 4 IRFP240 and 6 transistors. https://s23.postimg.org/l8onxw1wb/image.jpg https://s17.postimg.org/czg1ynam7/image.jpg BTW the transformer shows 45-0-45 VAC but when i test with a multimeter, the VAC is 53volts. Thank you. Regards.

Question by Lima79   |  last reply

AC MOT Welder Voltage Issue

Hello everyone, I've been working on an arc welder based on instructables like https://www.instructables.com/id/Small-110-volt-arc-welder-NYDG/ but I need some advice. Most tutorials on here suggest two paths to success, either winding two MOTs with as much 10 gauge wire as possible, hoping that the voltage output in series will be close enough to 40V, or using multiple small transformers, also in series. The problem is, all this series stuff really cuts down on the available amperage, so I'm wondering if there's a different way to get high amps and volts simultaneously (obviously without surpassing the available 2400 Watts, energy in = energy out). I think I have a way to make two MOTs which run at low voltage but high amperage also have high voltage. I've made a high frequency circuit to assist in starting an arc, which you can see attached (it works phenomenally, and I've been able to make it run on 1 amp). Since the output on the HF part goes through a torroid at the far right (where it meets the welder's output), would it be possible to wind the torroid with, say, 5:20 turns, to basically take the 120A (10.8V) I get from the parallel-connected MOT transformers and overlay a low-amperage but higher voltage on it, to make arc start/run easier? The welder just won't run at 10.8v, so other than rewinding the secondaries, what about jumping the voltage up a little via the output torroid?

Topic by reakter 

Rewinding a DC motor for different voltages

I modified small DC motors, like used in toys and such but now I have one that requires to do it properly.Motor in question runs on 24V and uses about 3.5A under full load.Drives a high pressure water pump on either side of the shaft.The rotor is basically empty with just a few turns of wire and lots of empty space.I assume the same model is used for multiple power configurations by the manufacturer.For the toys my basic approach was to just calculated the number of turns or to count them when removing.From there I get the voltage per turn and can rewind accordingly.So in theory and by blissfully ignoring all higher things involved I could do this motor the same way.Right now I see 10 windings per coil, so with thicker wire I would use 5 to run it on 12V at roughly the same speed.Only problem is that thing then would use around 7.5 to 8A when running under full load and get quite hot.I need the speed to keep the flowrate at the same 7.5L per minute but I also need the power to be able to still get the 120PSI from just 12V.Isn't there any winding trickery that would allow me to reduce the required current a bit without sacrificing on speed or torque?

Topic by Downunder35m   |  last reply

I need an AC Voltage Stabilizer?

I have low voltage at my place which keeps on going even lower at night. I need to create an AC voltage stabilizer to keep the power at the required level (230v 50Hz)?

Question by nabulomi   |  last reply

Convert battery power to low voltage?

Is there an easy way to convert a security system sensor from battery (2 3V lithium batteries) to a wired low voltage line? I have pulled the cover off the sensor (image attached) and it doesn't look too complicated. Other options would be to convert it to POE or USB. Don't know if that's doable or practical. I'm building a house and have an opportunity to never have to replace those batteries, which are not on my "be nice to the environment" list. I have plenty of low-voltage in the house already. There is also built-in solar backup for 12-15 hours for power outages. Thanks for the help.

Question by lgpitman   |  last reply

Combustion Chamber for high voltage spark

Based on Sir9's project http://sdch2o.free.fr/vrac/Sir9-Plasma-Steam-Engine.doc I am preparing to make my own version: The plan is to create a Tesla Turbine powered by steam which is made on the plasma spark from a Tesla Coil - Presumably if Sir9 used just 110 V, the really high voltage of the Tesla Coil should give me Big effects I am not sure about what size, shape and material I should use for the combustion chamber, and whether I can use multiple spark plugs safely. I'm planning to use a small 220v // 2,1kV microwave oven transormer for the coil just to keep things farely safe for the beginning and a turbine made of hard disk drives (about 16 plates) sealed in a plexi-glass chamber I have a lot more questions coming up every minute, need any help I can get - this is my first project of it's kind Thnx

Topic by skyw4lker   |  last reply

How to Slow Down a 240Vac Electric Motor?

I bought a small, industrial motor and want to safely slow it's rpm.  Does anyone have any advice as how to best go about this?  I've looked into gearing and found this to be quite complex but understand that an alternative option may be to change the voltage received by the motor?  Thank you for any help you provide

Question by ambrosiaceae   |  last reply

240v to 75kv transformer, shell type? Double winding? Need sum help please!!!!!

Hello! So I found this transformer the other day, it's a 240v to 75kv here where it's gets interesting, it's a shell type, with two separate transformers I'm guessing. It has a input for 240v on each end, it has 1-5 taps but 1 is not used 2 is phase 3 is neutral 4 is earth and 5 is not used. It only has condanuity between 2 and 3 on 240v side. On the high voltage side it has only one output and no condanuity to the core or anywhere, So I'm confused. I'm wanting to make it in to a high voltage Jacobs ladder setup. I have a varic that is 240v and goes from 1v up to 280v on the wiper side it is motor driven. Can I arc between the two hv posts? Also both transformers are have the same phase in parallel. Please help me!!!!! Thanks! 

Topic by nz dude   |  last reply

Variable Voltage battery charger for nicads and nimh?

I would like to build a charger wherein I could specify up to what voltage to charge my nicads and nimh batteries. I'm currently using a la crosse bc-700 smart charger. it usually charges my batteries to 1.44-1.46v. I would like to build a charger that will cut off, say 1.38v.  Is that possible?  Thanks.

Question by cebulifer   |  last reply

What are the voltage and amperage of a transformer that will be used to build a welder? Answered

In order to build a welder using 120 volts of AC, what should be the voltage and amperage rating of the transformer? 

Question by blkhawk   |  last reply

Voltage regulator to get from 70vac back to 120vac?

Hi all, I am using (and for strange reasons am required to use) track light outlet adapters to power some LED light strips. The LEDs use an AC adapter that requires a minimum 100vac to run properly. The problem is that the track lights are dimmed substantially, so the voltage coming from the tracks is only 70vac. Any idea what I can use to bump the voltage back up to the 100+ voltage range? Tripp Lite has a some regulators, but they don't go down to 70vac. APC makes one that goes down to 80vac, but that's the lowest I've found. Is there an off-the-shelf regulator that goes down to 70 volts? I found this contraption that looks promising and maybe a little sketchy (alibaba style). Any other recommendations? I guess the other question is what is the risk in running the LED strip lights if their AC adapters are getting 30v lower than they recommend? The lights appear to function fine, but will the adapter overheat? Burn out quickly? Cause a fire? If it burns out, say, once a year, I'll probably leave it, but I have no idea what the consequences are. Thanks in advance! 0    ..    o uuuuuu nnnnnn

Question by uuuuuunnnnnn   |  last reply

Protecting my new power supply

I've got a 12vdc 500ma power supply that I'm using to trigger a few solid state relays. I'm also using the same power supply to provide input current to a little micro PLC (Automation Direct DL05). Both the relays and the PLC have a wide range of acceptable input voltages and their current requirements are about 15ma per channel at 12 volts. The count is 6 relays and 8 PLC inputs, if all are on thats about 210ma. I once killed a similar power supply by allowing the leads to touch and short-out. I would like to protect this power supply from the same fate by protecting it from short circuit. I thought about attaching a reisistor to the end of one lead and covering all but the outlet of the resistor with heat shrink tubing... problem is, it would have to be a big, bulky power resistor to handle the wattage. Is there a simple component available that will limit the current upon short circuit that I can place in series with my loads to protect the power supply? As I said, it doesn't have to be precise and it doesn't matter if it jerks the voltage around a little.

Topic by fluoronator   |  last reply

Tesla Coil Capacitor help

I have just started building my first tesla coil. I am fairly experienced with electrical stuff and high voltage but I can't seem to get past building a homemade capacitor that will work. My first attempt I built eight Leyden jars in parallel that were constructed from glass canning jars and metal tape. Next I tried lining a 5-gallon bucket inside out with aluminum foil. Lastly I tried assembled a rolled capacitor with aluminum foil as the plates and wax paper as the dielectric (about 10 square feet). All of these have failed in a similar fashion; I hook them into the circuit and the spark gap wont fire. There is no arcing however the bucket and jar constructions made a faint noise similar to a capacitor charging. I have seen instructables and videos with only three or four Leyden jars in parallel and the spark gap is firing. I don't know whether the homemade ones just don’t have enough capacitance or if it is something else. If anybody has any input on the problem please help. P.S. I am using a 14kv 35ma 60hz oil burner ignition to power the coil below is a diagram of the circuit configuration

Topic by hmf444   |  last reply

Reducing 110v transformer output? Answered

Hi all, as stated in the title I need to reduce the output of a 110VAC transformer. I'm using a US graco spray gun that is 60hz, and I understand that if I reduce the voltage to 90 this will compensate for the UK 50hz system. Any help is greatly appreciated

Question by dimmaz88   |  last reply

Alternator use and output

Hail the reader and Bless the respondent. please can someone tell me the following 1. At what speed must a normal vehicle alternator turn to give max output... and what is this out put... I see my charge meter shows it charging at 10 amps... how long to fill the battery at 10 amps? 2. A pack of 6 12v truck batteries connected to make 1 big 12 volt battery... is it possible to charge this pack from more than 1 alternator and will it speed up the charge time to make the battery full to max?

Topic by carnut34   |  last reply

i need more amps for my hho generator.......HELPPPPPPP

I've built a hho generator (the spiral electrodes kind) and am trying to use it as a welder i use salt as my electrolyte (should i use something else???) THE PROBLEM IS THAT WHILE I DO GET A CONSTANT FLAME, I DON'T GET A BIG ENOUGH FLAME (it melts metal but it takes ages to do so) does anyone know of a way how i could get more amps to speed up gas production or of any way i could get more preasure (+maybe my gas isn't pure enough because i use salt as an electrolyte, could that be it?)

Topic by CrtSuznik   |  last reply

High voltage in water increases surface tention. Why?

One day, I stuck two high voltage wires (even thought you may think this was not smart) and it made water "stick" to the ends of the wires, and it was as if there was sticky jello on top. Does anyone know why this happened and what I can do with it?

Topic by ANDY!   |  last reply

How to limit DC current without affecting Voltage?

I would like to be able to choke current example 12-20amps from the 40amp peak to peak keeping voltage level to rise when the current begins to fall again as stabling after a huge load peak. This will preserve energy consumption on my circuit. Things ive researched Transformer choke Current limit thorough chips add a pwm and control (expensive and time consuming)

Question by ArturoC6   |  last reply

Managing high-voltage lithium-ion batteries in HEVs

From EDN (Electronic Design News), comes this article: Skyrocketing energy prices and the growing concern over carbon emissions have focused attention on electric and hybrid-electric vehicles. New lithium-battery designs will be key technologies for efficient EVs and HEVs.By Michael Kultgen, Linear Technology Corp -- EDN, 4/9/2009Safely getting the most energy and lifetime from a lithium cell requires some sophisticated electronics. One requirement, for example, is the ability to measure the voltage across every 3.7V battery cell in a stack of 100 series-connected cells. How do you cope with the 370V of common-mode voltage and reject 100V of common-mode switching transients? The design of battery-management systems for EV (electric-vehicle), HEV (hybrid-electric-vehicle), and UPS (uninterruptible-power-supply) applications requires solving many such problems.How do batteries make cars "green," ...http://www.edn.com/article/CA6648791.html?nid=2432&rid;=8848980

Topic by Goodhart 

How to prevent voltage drop on solar phone charger?

Hello folks, I made a solar phone charger - cell (12V 400mA - at peak 5W)  and step down DC/DC converter R-785.0-1.0 (5V up to 1000mA). and I am using it as direct charger for my phone (no batteries). When the sun is bright, everything is fine and phone is being charged almost by 1A. When the dark comes, everything is fine - no charging but also no discharging of the phone to a solar cell. Problem is in the middle, sunlight but not so much. Voltage on cell drops to 6,5 V because converter wants more power and cell cant support that (output is still 5V but almost no Amps). Problem is, that charging circuit in phone is constantly switching on and off(as the load is pluged unpluged) and that can run down fully charged battery within 10 minutes. Is there any solution how to prevent that?- for example some kind of minimum current limiter? Or I saw using 555 timer as a charger controler, but not sure how to use it. Main goal is to prevent that oscilation. Many thanks in advance.       

Question by HanoCZ   |  last reply

Charge 2x AA batteries via USB - Voltage Question? Answered

Hi there,  I guess I didn't pay much attention, especially in some classes when I should have too :) I am DIY-ing a little project, and I need to charge two AA batteries (2450 mAh) via a PCB that get's charged via USB (5V),  here are the specs of the PCB:  Input voltage DC5V Input Current 2A Transmit power 5W Charging voltage 5V Charge Current 500-1000MmA My dilemma is - can I charge (both batteries together) safely with this voltage and current? I looked of course at some "usb aa chargers",but the problem is that i have no space for an extra pcb in the battery department. Thanks a lot if anyone answers, George

Question by grancharov   |  last reply

Battery Power in a Taser

Hey, I'm making a 'Glove' Taser using a disposable camera and I wanted to know a few things which most people who read this will laugh at. Firstly, I wanted to put a stronger battery into it and wanted to know what the best battery to use was, keeping in mind that I wanted it to be hidden so I can't use C or D batteries or anything like that. And secondly whether by soldering more wire strands to my contact points (the hurty bits) whether it would carry a greater charge? ie, if 5 strands of copper wire carries 'X' charge then maybe 15 strands would carry '3X' charge. Any help here would be a huge bonus and when I make my Instructable on my Glove Taser I'll give credit to anyone who tried to help me XD

Topic by grantdevine   |  last reply


There are soo many who ask for High Voltage generation. Here is a good deal for as long as the stock is available. http://www.mpja.com/email/11-01-11.asp?r=214011&s;=14 A 5 VDC  input  and 400 VAC output for $3.  .  .  .  .  .    A

Topic by iceng 

Using 110v 60Hz Soldering station with 240v 50Hz?

Hi, I have recently acquired a 110v 60Hz Soldering station but i live in a country which uses 240v at 50Hz. I can get a stepdown transformer to convert the voltage (can choose between 50W and 1600W), but i am wondering will the different frequency damage the soldering station? The soldering station i got is https://www.sparkfun.com/products/10707

Question by michaelgohjs   |  last reply

Carbon Button Lamp

The Nikola Tesla group forum is asking for new projects, so I'm posting this as a suggestion. I would love to build it myself, but I lack the tools and money. This is my first contribution to Instructables, so please comment constructively. Nikola Tesla invented the Carbon Button lamp as a kind of incandescent light, because Thomas Edison banned him from using his incandescent filament bulbs. Nikola later discovered that versions of it could also be used in wireless, trans-Atlantic telegraphy, and to investigate what we now call x rays. In fact, he even used the lamp (or something similar to it) to take x-ray photographs, 8 years before Wilhelm Rotgen discovered them.For this reason, I must warn you: this device may possibly generate x rays. I am not responsible for any harm of any kind that may or may not result from re-creating this interesting device. There are phosphors that you can buy that will absorb x rays and re-emit them as visible light. I recommend that you coat the bulb with it until you know for sure that the x rays aren't strong enough to hurt you, or if makes x rays at all. Mixing it with a phosphor made for uv light wouldn't hurt either. Theory of Operation:The bulb is powered by a Tesla Coil, or other source of high voltage, high frequency current, such as a driver for a plasma globe (actually, the modern plasma globe is descended from this kind of technology!)When the power is turned on, electricity bombards the carbon button. Because carbon isn't the best conductor, this causes the button to heat and release electrons into the bulb's vacuum (the technical name for this is "thermionic emission," or the "Edison effect") . These electrons, in turn, excite the remaining air molecules and cause them to create visible light. This is strikingly similar to how fluorescent lamps work!Supposedly, the bulb should shine 10 times brighter than an incandescent bulb.(Note that the excitation of the air molecules, not the incandescence of the button, is actually the main source of light from the bulb.)If anyone decides to build it, please post an instructable showing the steps and finished product. I suggest you get started by reading the patent, number 514,170. You may also want to read part of Tesla's lecture, "Experiments with Alternate Currents of High Potential and High Frequency."To anyone who will attempt this, I wish you good luck!

Topic by ElectricUmbrella   |  last reply

LED Questions

Help, I'm afflicted with inspiration in quantities that exceed my skills!So I came up with an idea for a project that would probably require the use of LEDs, which I know next to nothing about. Ah, said I, the Internet can teach me much... so I turned here and found the (nearly) perfect Instructable, "LEDs for Beginners":https://www.instructables.com/id/LEDs-for-Beginners/Having read this most helpful I'ble, I certainly came away more knowledge than I'd previously had, but still not enough to properly plan my project.Basically, I'd like to create a 2D "array" of LEDs to use as a light source, in order to backlight a roughly 8.5" x 11" translucent panel.It seems like it would be straightforward to just wire up a bunch of white LEDs in series to a power source and a resistor, and be done. I'm not afraid of a little trial-and-error, but I prefer to know at least roughly what I'm doing going in, so I'm asking for your help. Here are my lingering questions:1. Should I wire my LEDs in series, or in parallel? (Or some combination thereof)? In series, I gather that one LED failing will break the whole circuit, which could be a pain. On the other hand, I've seen several projects and sites that cryptically recommend against wiring these in parallel.2. Are there pre-built strips of LEDs I could acquire that would make this project simpler?3. If I want to vary the brightness of my light source, can I use a variable resistor (potentiometer), or does the nature of the LEDs preclude the use of this type of dimmer switch? If so, could I vary the brightness with multiple switched circuits, turning off half the LEDs for half brightness, 3/4 off for quarter-brightness, etc?4. I've got a slew of transformers from old tape decks, telephones, cell phone chargers, etc. Can I appropriate one of these as my DC power supply?5. How do I gauge how many LEDs I'll need, and what density is best to lay them out? I'm looking to create even, diffuse light, with no noticible bright/dark spots.6. Do I need to worry about heat?7. Are LEDs even the correct way to go here? Should I consider fluorescent light instead?I realize these are a lot of questions, but if you're an expert on LED projects, you could save me a lot of research time. If (I build this gadget, it will definitely show up here as its own Instructable.)Thanks!-JD

Topic by jdtwelve12   |  last reply

Which transistor is best for joule thief between BC107 and BC547?

I want to make a joule thief to run led's from my death batteries.I have 2 transistors,BC547 AND BC107. Which transistor should I use to make a low voltage joule thief ?

Question by Crazynventor   |  last reply

inverter circuit

I have several BD139 transistors, several types of transformers, blocker diodes and 40pf 50v capacitors. can anyone show me a simple schematic to convert low voltage to high voltage?

Topic by buddybro   |  last reply

Phenolic discs for whimshurts? Answered

So recently I found a webpage about someone using Phenol for a rotary spark gap for a Tesla, I had never heard of this material and don't know too much about it. For a while now I have wanted to make a whimshurst that is larger than the one I currently have (bought online, a gift from my family) but with my current one i have an issue with the acrylic discs not only not being balanced but also warped causing them to start vibrating on their shaft making it harder to turn the handle. I figure that because every piece of acrylic i have ever worked with has been warped that is would be best to find an alternative. My question is, would it be easier to keep phenol flat and balance or would it be best to stick with acrylic? another thing im curious about is this a material that would even work for this application? Lastly i would like to say that i did try doing a little research on this and didnt come up with anyone trying it for this purpose, i know that in some cases static can act a little differently than normal high voltage arcs (say, from a microwave oven transformer) which brings me to this question. P.S. im not sure what category this should go in, if anyone thinks there is a better one let me know and i will change it.

Question by pmk222   |  last reply

do i need a sort of voltage regulator to charge rechargeable batteries with a low voltage, around 2/3v charging input?

I am building a thermo-electric generator from the design showed by this inscrutable    https://www.instructables.com/id/How-to-build-a-thermoelectric-lamp/ my main idea is to be able to charge rechargeable batteries from this to be able to charge a more powerful item like a phone for a larger period of time, i already have a joule thief to up the energy but this still seems like it is going to be a bit weak and only able to charge when heat is applied , all the voltage details are in the instructable i used above

Question by On The 3dge   |  last reply

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!

Question by ANDY!   |  last reply

home made battery

How to make powerful home made battery  weight 3 to 4 kg voltage 12v

Question by vpsingh92   |  last reply

Any objections to my battery charging solution? Answered

I bought some cheap 360 battery packs on the internet and big surprise they don't work.  The problem is that the built in charging circuit charges the packs to around 2.26v when my controller wont turn on until closer to 2.5v.  My idea is to use the indicating LED (that came as part of the pack) that has a forward voltage of around 2v to drop the 5v charging voltage down to 3v and charge the packs to that voltage.  Theoretically when the packs reach 3v the LED will not be able to sustain the forward voltage and will turn off stopping current flow to the batteries and thus stop charging.  I have a lot of knowledge about electronics, however my knowledge of batteries and their sensitivities is just about nill so I thought I'd ask here before I rig this together and get an idea of the likelihood of the batteries blowing up.  I've attached an image of the proposed circuit any knowledge would be greatly appreciated.

Question by double_g   |  last reply

Why aren't coil guns made this way?

In a physics demo, my teacher used a small coilgun,  but it used low voltage AC, not a single high voltage burst, also it used an aluminum ring on the outside of the coil instead of a slug on inside of it. Apparently the AC creates a changing magnetic field, which induces current in the ring giving it a magnetic field as well...

Question by falzarbeta   |  last reply

3 phase to 240v?

I have a sauna heater Voltage: 380~400 V 3N~ is there any well of wiring it up to 240v 

Question by gary.beecroft.92   |  last reply

A speciel stepdown converter?

Hello guys of instructables! I'm writing on this forum, because I think you the only guys that can help me! My situation: I'm from Europe (Nordic part), and our voltage/hertz is 230v 50hz - I think. What I'm trying to do is using american clippers here in my country, but what I've experienced is that it really going to work because the magnetic motor in the hair clipper is going to make alot of noise and overheat, even tho if you used a stepdown converter (230v to 110v) My request: But yesterday i saw a guy on youtube which said that he had made a revolutionary stepdown converter, that would solve the problem and make american clippers anywhere in Europe - without overheating and noise. Here is the video:  http://youtu.be/I2Ybj1BKjYk?list=UUpnyPxtX9XwOJZbN8qwVoLg And here is a ebay link of the converter: http://www.ebay.ie/itm/181496829039 I think its a bit of a overprice (119.3575$) and I was wondering if there is an alternative, where can either make it myself or buy one as good as that one with same specs and quality.. I hope you guys can help me, I'm a bit of unexperienced guy when it comes to electronics so bare with me.. - josh

Question by joshua1993 

electro cleaning before electroplating

Hi. I made the instructable of A_Steingrube"high quality and safe nickel plating" address:https://www.instructables.com/id/High-Quality-and-safe-Nickel-Plating/ and i want to be sure that i did the elctro-cleanning that is mention on step 4 correctly. I try to ask A_Steingrube through the comment place and the private message but i have not get any answer yet.so i try to ask here. I made the elctro cleaning while my object was connected to the positive voltage and the wire connected to the negative voltage.I did that ,because i understand that the object sould be dissolved abit and this should be happens on the anode(connected to the positive voltage) but in step 4 he mention to connect the object to the negative voltage in order to make the electrocleanning.SO,is there something that i miss here? Thanks in advance.

Topic by xchcui   |  last reply

Transformer not behaving...

I hope someone here can help.  I have a AC to AC step down Unrectified transformer, i.e., no circuit board whatsoever.  Primary winding has continuity, secondary wire has continuity.  No continuity between primary and secondary wires in any way.  In short, power goes in, but no voltage comes out.  If someone that knows precisely how transformers work can explain to me how a magnetic field can be generated but no electricity generated on the 2ndary wire I would appreciate it.

Topic by PeterE56   |  last reply

What voltage / amperage / frequencies can I expect from the tach line of a 2001 eclipse v6?

The question is all in the title, but any way.  What numbers can I expect to see from the tachometer signal line of my 2001 mitsubishi eclipse v6?  I've read that some times it can be like 3 cycles for every 1 RPM.  I would assume it was running at 12 volts, but is this false?  What kind of amperage could I expect to be pulled on that line as well?  I plan on connecting an arduino to this to get the frequency as an input (new new new newbie to arduinos!).  Can I expect to need to step down the voltage, if so, how?  Is there some basic principle or standard for the tach line that I am unaware of?  Any help with the tach line info or how I should connect it to the atmega chip would be AWESOMELY helpful!!! -James

Question by sephiroth67   |  last reply

LED 3 Watt Testing

I recently purchased 13- 3 watt LED's.  I'm trying to establish a high out put LED light.  I also purchased a LED Driver Transformer 48 Watt 120 Volt to 12v DC 4 Amp. First I would like to test each LED using the same divider.  I'm thinking that if I create a voltage divider two 330 ohms to limit the current and reduce the voltage to about 6 volts that would allow me to test with the driver that I purchased.  Secondly, will this driver be enough to drive all my LED's and would I have to reduce the voltage down too since it appears to push out enough wattage and amperage for the total number LED's I'm putting together?   I'm building my circuit based on this video. http://www.youtube.com/watch?v=4qYZahe2s5o&NR;=1   Assistance would be greatly appreciated.  Regards,

Topic by lancruz   |  last reply

can i use motor to run the small generator instead of fuel engine?

I want to know which card i will use to control the voltage and frequency and speed.

Question by geminiyasir   |  last reply