How to Reuse Toroids

I am trying to re use some toroids that I salvaged from a broken computer PSU and motherboard. I have some electronics experience however this is mainly with digital circuits. I am reusing the toroids by removing the original windings and hand winding the several coils required by the circuit. I have noticed that while the one largest (2.2cm diameter) core works exceptionally well, all other cores salvaged from the devices work poorly. My goal is driving a nixie tube. While the "successful" core yields about 180 volts AC the rest can barely top 60v output (all have similar numbers of windings, roughly 150 turns on the primary, 5tap5 on the secondary, 10 on the feedback). Clearly there is some level of variation between how the toroids perform. Is there any easy way to work out which cores will work? Can anybody explain which factor(s) are likely to be the cause? Visually the cores appear to be the same, looking like they are all made of soft iron. For reference, I am using the toroids to make a Royer oscillator - which does appear to be working, as my source voltage is 5V. Any help appreciated, Thanks, Drew.

Topic by andy   |  last reply


What's the best way to scavenge toroids?

What are they commonly found in? And are those things easy to get for free?

Question by Zem   |  last reply


What material should you use to re-insulate a chipped/burnt toroid ... when replacement is not an option? Answered

Here are pics of said toroid - http://imgur.com/a/Z0hC8 - I'm planning to replace the wrapped wire, just need advice on what to use to cover up the broken insulation on the actual toroid?  I've tried nail polish, however it heated up and smoked against the bare wire (hadn't yet rewired it when tested). The toroid is on a Power Supply.  Replacing the entire PSU is not an option.

Question by cowpuck   |  last reply


Jule thief transformer issues. Answered

I'm trying to make a Jule thief, I set up the circuit and tested it using a salvaged transformer and it works fine the only problem is that the salvaged transformer is kinda large. So i decide to try to make a smaller transformer using a Radio Shack T4452-1R2L choke and 26 gauge magnet wire. i managed to fit 15 pairs of windings onto the T4452-1R2L Toroid, but when i tested it the led won't light up. I tested the wires for shorts using a multi-meter and even tipple checked that it was wired correctly. Is this Toroid just not suitable for use in transformers of this kind or do i need to use a smaller gauge wire or is there something I am overlooking?

Question by FrozenKnight   |  last reply


how does a toroid in Joule Thief circuit work? Answered

Sorry for the noob question, but i can't understand how a toroid can cause a LED with higher voltage than the source to be lit.. i tried to make it without the toroid (only the transistor) but it didn't work... any explanation is much appreciated.. tq..

Question by firdaus_alizh   |  last reply


I have a few toroidal transformers and want to do something with them...

It seems like I see posts where people say, "but I didn't want to spend x for a big toroid....". Well, I have what I think are some pretty big toroids, the part number is TOG543021F0 and they are made by TENPAO. I think they are 230V? I have a half a dozen new ones and another 10 or so used ones that look brand new...? What about a desktop tesla coil or a coil gun?

Question by cwleveck   |  last reply


Any tips on winding a toroid properly? Answered

Every time I try to wind a toroid for a circuit, it never works or it is very temperamental and does not cooperate with me. Any advice on how to wind a better toroid?                                                                                                                                                                                                                                                         Thanks! 

Question by transistorguy   |  last reply


is there any electrical connection between toroid and the secondary winding in Tesla Coil? Answered

i have secondary on a 2.5 inch PVC and my toroid is made of aluminum duct .  now i want to know whether there is any electrical connection between these 2 ?

Question by sudhanshu529   |  last reply


I want to make a joule thief to power a 10W LED (833ma @ 12v) from ~2 AA batteries, suggestions on toroid ? # of turns ?

My transistor inventory: Part #          Package TIP122       TO-220 TIP32          TO-220 2N2222      SMD 2N3904      TO-92 2N3906      TO-92 C1815        TO-92 BC546        TO-92

Question by yaly   |  last reply


joule thief won't work for me, can't figure out the problem

i made joule thief as shown everywhere in instructables, I tried few different transistors, and toroids, I had like 100 tries, and can't get it to work? and: can I use transistors-in the middle of the last picture?

Question by xtony666   |  last reply


How to create 120 VAC to 90 VDC Power Supply?

I need to create a 90 Volt DC Power Supply using a capacity, toroid and bridge rectifier. I know that with a toroid you have a primary (input) voltage and then you'll conserve power but have a different secondary (output) voltage. I know that if you put say 120 VAC in the primary, the outputs might be, for example, 50 Volts out, which are also AC. I want the voltage to be DC, so I know that I need a bridge rectifier that will boost the voltage by 1.41 because of the AC to DC conversion. However, you also need a big fat capacitor, and I have no idea how to size and select this. Help?

Question by Matt Adams   |  last reply


Alright.. So can someone explain to me what each part of a joule thief does? I understand the LED, Resistors and battery Answered

So, in a recent Instructable about a Joule Thief, I was slapped in the face with a gap in my knowledge. I have no idea what the toroid DOES, I know it's an inductor... but is it suppose to transform low voltage to higher voltage? What happens If I wind it more? How about less? What does the transistor in this setup do? In a recent Instructable, as I was saying, they did it with only a regular inductor. I'm in the middle of finals too, my brain feels over used...

Question by Junk_Wizard   |  last reply


What kind of a toroid (specifically) do you need to make a joule thief? Answered

I've literally looked everywhere for what kind of a toroid you need for a joule thief, but no one gives a specific number range or type; the most specific was, "high permeability ferrite toroid". I've been searching high and low for a reasonably priced (including shipping) high permeability toroid for over a week, and I've ended up empty-handed. What's considered "high" permeability? The best one within my price range seems to be a pack of FT50A-75 toroids that I found on eBay. I looked up the specs: Inner Diameter:  0.312  inches Outer Diameter:  0.500  inches Height:  0.250  inches AL Value:  3000  µH/100 turns Which would be 300nH per single turn? Is that high or low permeability? Will it work on a joule thief? Am I making a mountain out of a mole hill? Can I just buy the cheapest ones I can find on eBay? (Even though the seller even specified "low permeability" in the description?) And I don't have any old electronics that I could try to take apart to salvage it from. Please don't say to just buy it and try it... It's about 6 bucks, but I'm in a situation where I really need to save every dollar I can. I really can't afford to just spend money on something that might not work. If it doesn't work - and I'm usually unlucky, so we can assume that it won't - I'll have to buy more, for probably a more expensive price, and that's more money that I just can't risk. Money is a big factor, so what's the cheapest toroid that I can get?

Question by a Canadian   |  last reply


Ferrite Beads

I want to make one of those joule thiefs and I live in the USA. I don't know why I want to make it, I'd never need it/use it... BUT I MUST HAVE IT!!! I'm looking for tiny ferrite beads (toroidal shape) that are cheap (less than 10cents a piece). They CANNOT be leaded

Topic by guyfrom7up   |  last reply


How many windings do I need on a toroid to make a joule thief work?

How many windings do I need on a toroid to make a joule thief work? Is there a min and or max number of winding? Is the toroid acting as a one-to-one transformer? Can I use anything as the iron core? Is there a calculation to find this out? Thanks for any help.

Question by daemonral   |  last reply


Where can i find a ferrite toroid for my joule thief? Answered

Where can i find a ferrite toroid for my joule thief? Iv'e opened almost all the devices in my house!!! Just wanted to make a simple joule theif. I dont have any CFL's to open.

Question by TheMasterThingMaker   |  last reply


Joule Thief Toroid not helping to step up, Why? Answered

Hey fellas..I am having problems with joule thieves especially with the toroid part.... First time I wound my Ferrite Core and the joule thief ran smoothly... But recently I had to unwind it to try other wires which didn't work.. So i again wound up the toroid just like the first time when it used to work but unfortunately this time it didn't work... I have checked everything and found that the only problem is that the toroid is not helping to step up the voltage.. When i applied 9V across it, the LED glowed but for 1.5V it didn't. So there is a problem with the toroid.. But what it is and why is it happening I don't know..I mean for the same core and same style of winding once it worked and now it doesn't, Why ?? Can anyone help me ??

Question by Arijit Chatterjee   |  last reply


How to build a joule thief? Answered

      I'm building a voltaic cell and a joule thief. I searched on some instructables and followed the one on youtube by MAKE:. When I hook up a 9V for a few seconds (To not burn the LED out), it works. However, a AA doesn't work. Not even a brand new one. So, I presume that I haven't wrapped the toroid around enough to create more voltage and lessen the amperage (If that's what joule thieves do)? I posted some pictures below. Also, I'm looking to buy a voltmeter, I'm around basic level and just need to measure if the joule thief is even increasing voltage (For now at least). Here are some cheap ones I'm looking at on amazon:  http://goo.gl/gVvo6P http://goo.gl/hKKtGu http://goo.gl/Q2rrKm http://goo.gl/MQZeeS http://goo.gl/if04Es Some of those have autoranging, is this to automatically find the voltage/amperage? Thanks, please reply

Question by knexpert1700   |  last reply


Any particular uses (electronic) for long ferrite beads? (toroids)?

Am aware of toroidal ferrite txformers used in Joule Thief apps,any other uses for the 'longer' ferrites ?

Question by chadeau   |  last reply


Where can i get small toroids for magnetic core memory?

I have really wanted to do this but I could never find those pesky rings!

Question by seanroberts   |  last reply


Cannon printer motor 24v Answered

What is the use of this toroid here?

Question by sooraj619   |  last reply


What would you do with 2 very large toroidal transformers? Answered

I found a few of these http://www.alliedelec.com/search/productdetail.aspx?sku=70181130   while salvaging pelican cases. They're really expensive, so I imagine they must be useful for something. Any ideas? Brand/Series :  182 Series Configuration :  Toroidal Current, Secondary :  10/5 A Dimensions :  2.27"H×5.06"O.D Frequency :  50/60 Hz Length, Lead :  8 " Mounting Type :  Panel/Chassis Number of Outlets :  2 Phase :  1 Power, Rating :  300 VA Primary Type :  Dual Standards :  UL, CSA, CE Termination :  Leadwires Type :  Power Voltage, Primary :  117/234 VAC Voltage, Secondary :  30/60 VAC Weight :  5.58 lbs.

Question by Nate Cougill   |  last reply


Is there any use for the tiny transformers in compact florescent light bulbs? Answered

Can the tiny little transformers be of use in simple electronic experiments? Can they be used in place of a toroid in a Joule thief?

Question by brandegor   |  last reply


First Tesla Coil Answered

I purchased a small tesla coil kit online.  The kit is working but I need help improving it. Instead of having the typical primary and secondary windings with a toroid on top it has the driver circuit pulse a 50k transformer producing a 1 inch spark.  I'm wondering can the output of the transformer be connect to a typical primary windings and secondary windings with a toroid on top? I have a link below to the schematic. Also if this works would you recommend 1000 or 2000 turns on the secondary and how many on the primary?  30 or 36 gauge for the secondary? Link to schematic http://i92.photobucket.com/albums/l23/tucsoninsurance/Public%20Album/20130925_203001_zpse3c1927d.jpg Here is a link to the tesla coil  picture.  http://i92.photobucket.com/albums/l23/tucsoninsurance/Public%20Album/20130925_203600_zpsc84f3177.jpg Thanks for your help.

Question by mpatti75   |  last reply


How to make a lightweight 10kv 500 watt power supply?

I need to convert up to 500 watts of 12 volt to at least 10 kv. It's important that it has both +10kv and -10kv. Right now I'm thinking flyback converter driven by a 555 to 1000 volts then voltage multiplier to 16kv. It's important that it's light so I don't want a regular flyback transformer. I'm wondering how duty cycle effects a transformer. Does it effect it like it would with an inductor-based boost converter? If so, then according to this calculator http://www.ladyada.net/library/diyboostcalc.html I would need an 88% (88% high?) duty cycle to get 12 volts up to 100 volts with a boost converter. Does this mean with a 1-10 transformer I could get 1000 volts from 12 volts with an 88% duty cycle? If so, then I need a light weight 1-10 transformer. I'm thinking winding a toroidal transformer will be best? So I could get a ferrite toroid (I'm thinking material 61, size 114) and wind a 1-10 transformer, but I need to make sure it doesn't saturate. Do I find out the saturation just like I would an inductor in a boost converter? If so, then according to the same calculator, the higher the output current, the less henries I need. So that means if I don't draw enough power it will saturate? I'm probably going to use 25 khz, so according the the calculator, if it's 100 watts then I need a little over a 25 henry primary. But if I use 500 watts, then I only need a little over 5 henries? This doesn't seem right. Soooo according to this toroid winding calculator http://www.66pacific.com/calculators/toroid_calc.aspx with a material 61, size 114 toroid, I would need 2 primary turns if it was drawing a minimum of 100 watts (the lower inductance/higher current can't be right can it?) and then I would need 200 turns. Sooo my question are (haha) is this a good idea for a light weight high power hv power supply, if so are the similarities I'm assuming between boost and flyback converter correct, and if so, how many/how do I figure out how many windings I would need on each side of a toroidal transformer/ how do I figure out what inductance I need for the primary. I have pretty good experience making boost converters but I've never made anything hv. Very long question thank you this is for an ion thruster.   

Question by sk8aseth   |  last reply


Joule thief is not working. Answered

I just made a joule thief and my led is not lighting up. I put a single AA and it wont power. My led does though require 3.6v and i gave it 3.7v for a few seconds and the transistor became extremely hot. Is there something i am doing wrong? I have a 1k resistor, a 2N2222 transistor, a led that requires 3.6v and 30ma, regular wire 26 awg, and a toroid bead.

Question by Munchys   |  last reply


Can anyone help with troubleshooting a tesla coil?

After working on a tesla coil off and on for a few years I finally finished building one, but it is running into several problems. The only problem that I can't figure out is that despite following the basic tesla coil diagram the toroid will not create a jumping spark; however the gap generator still produces a spark. The coil is running off of a 15kv nst with a gfi built in.

Question by Kaptia Teramo   |  last reply


My joule thief Lights my LED for a second then dies, can anyone help? Answered

My joule thief Lights my LED for a second then dies, I could only make it flicker by scratching two of the connections. I've used three different transistors but received the same result. The transistors were kn2222, pn2222 and 8050 (couldn't find Bc547,2n2222 etc). I had 18 loops around the toroid and a 100 ohm resistor, is there anything wrong with this and can I fix it?

Question by Zithe   |  last reply


Micro High Voltage

I'm going to attempt to make a super micro tesla coil that is 100% contained (unless it runs off of like 12 volts dc, then I'll use a wallwart). Of course, one of the i biggest problem is the power supply. So this is what I'm asking, what's the best way of ramping up the voltage? A tiny toroid transformer? An inductor that gets pulsed? Voltage Multiplier? Something with static electricity? Some type of Inverter? Using Greinacher Cascades? A marx generator hybrid? Other stuff I havn't heard of?

Topic by guyfrom7up   |  last reply


Joule thief is not working?

Learned about the Joule Thief from Make's Magazine and used their schematic. I'm pretty new to electronics so I don't know much about components. Applying 3 V, the LED lights up, but applying 1.5 V, no light. Green wire is 22 ga, blue wire is 26 ga. Using a 2N3904 Transistor and a Ferrite Toroid. I think I "barely" got the LED to dimly light up, but it would not stay on. Am I doing something wrong? Picture available in second comment.

Question by gera229   |  last reply


My try on the.... tesla coil. I need some help.

Hi. I made this tesla coil out of scrounged wire from a crt tv, a old 120 V.A.C to 12 V.A.C transformer (reversed), pvc pipe and a brass nob for the "toroid". When i plugged it in , the outlet i was plugging it into arced?! Do I have it wired right? I used the schemetics from the book "The Boy Scientist" by Popular Mechanics.                                                                    Thanks in advance. P.S: srry about the bad pics

Question by joespicnictables   |  last reply


I need help on to make a joule thief? Answered

I had made tons of joule thief, but the biggest problem is at beginning I had faced one problem, which is whenever I make it it can light up the led after some shaking,, (shaking causes some wires to touch the other in a way that is correct I guess).  But I follow the schematics, and then I finally made on that worked better, and without any toroid bead, but now with the new transistors I bought, none of them work anymore,  my old transistors got lost. so what can I do? 

Question by aninda13   |  last reply


Transformer modification? Answered

2 questions about transformers: - If a certain transformer (let's say, for a power amplifier) is needed, and for example, a microwave transformer is available, can the steel frame be cut to take out the secondary coil, to be replaced by a new one, and subsequently be re-attached (by clamps or so)? Would it need some treatment, like putting varnish, or oil over it?  Would this cutting and re- attaching cause a loss in efficiency, or cause heat build-up? Would it cause more noise in the output? - Some amps have a toroid transformer. Is this just fashionable or is it for a reason? Some industrial amps use sheets of copper instead of wire. Why is this better for industrial, why, and if not for common stuff...?

Question by BobS   |  last reply


How to make Joule Thief with Multiple LED and maintaining its brightness.

I've seen people running 61 LED or 100 LED on Joule Thief (1 AA Batt) with its full brightness. How did they do it?? I know how to build Joule Thief I have: -NPN   2N3904, 2N2222A, 2N4401   Transistors -Resistor   what I have now 1K, 560, 100.. -Toroid 12 turns and 20 turns -LEDs! -Batteries! Can anyone tell me what to do to run at least 10 LEDs with good or full brightness?

Question by jaesungauzakim   |  last reply


lets trade kits

I will trade for your random parts i mostly very big LED's or LED displays or any electronics you dont need that are in OK or acceptable condition for upcoming school science fair (don't live near radio shack) i will trade my electronics kit to you it includes.2-POSITION ROTARY SWITCH condition=mint about the size=of the tip of your thumb to the middle joint.3 pin stereo jack 2 peices condition=mintsize= of a nickel.mono and disk capacitor condition=OK (sightly scratched leads)1 film capacitor condition=mint1 resistor 260 Ohms condition=good1 toroid with copper wire 1 without condition=mintsize= 2cm in circumferencesize=a dimeIR RECEIVER FOR REMOTE CONTROL condition=okand 5 other unknown peices (sensors and capacitors)

Topic by albylovesscience   |  last reply


How do you remove that static noise on your computer when you plug in your earphones?

Well, whenever I plug in my earphones to either my laptop or my desktop, I would hear static noise. Rather, on my second desktop's amplifier I've hear little or mostly no static at all (from a sound card, through a audio plug to RCA into the amplifier) and as well seems to be little suppressed using a toroid band on the plug of the earphones. Through little research, I've found out its the grounded prong fault, where different resistance causes this noises. So, without either doing A) REMOVE THE GROUNDED PONG or B) Grounded loop isolator, unless I could find a cheap one, how would I stop this problem? Snowy *Updated: No, muting it will defeated the purpose of having music on*

Question by BIO Wolf   |  last reply


Efficient LED lighting? Answered

I want to power 3x 0.5W LEDs in series with 3x AA Ni-Mh batteries (input voltage will range from 2.5 to- 3.7 ). The total forward voltage is around 10volts, and the current of the LEDs is 150mA. I've tried using a Joule thief but it's quite inefficient, even with different transistor / toroid / resistor configurations (even with fast switching Darlington transistors) the maximum current I've been able to get at the LEDs is less than 100mA, and many energy gets lost in the process, it seems the resistor between the coil and the base of the transistor slows down the switching process and limits the current. I need a more efficient way to power the LED's, either an improved design or a LED driver chip. But trying to keep the efficiency rate around 60-70% or more. I have found a design that claims to be more efficient (see picture), but I'm not sure about if it will deliver 150mA.

Question by Victor805   |  last reply


Joule Thief. I know how they work, but is a joule thief self-regulating and self-limiting? Is a varying input (DC) okay?

Joule Thieves. I know how they work (my one works fine) , but is a joule thief self-regulating and self-limiting? Could I hook it up to a 12V source? Is a varying input voltage okay? -- Will the voltage/current across my white LED (should be 2.6VDC absolute max) be too high or surge? I would like to know if it would be suitable to use on my motorcycle to drive an additional LED or two for a headlight supplement. The voltage varies between 11.5VDC and 18.2VDC. I have a basic handmade circuit, with a hand-wound toroid and a generic transistor, usually running from a stable 1.1 to 1.6VDC, I have tried it with a 9V cell and it seems to work alright, but I want to be sure before modifying it/or my motorbike. Any help much appreciated! 8-)

Question by xerxesx20   |  last reply


Universal motor projects

Hello, everybody. I took apart a universal motor recently. The motor itself is broken and does not work. However, I would like to know whether I could rewind the copper coils around the silicon steel motor core in order to make a toroidal transformer.  I have heard that motor cores are sometimes grain oriented, which would significantly reduce my transformer performance. This motor is, however, about a decade old. I want to use the existing motor coil as a primary, and then wind thick power transmission line wire as a secondary in order to get a high amperage output. Is this possible? I would also like to know whether there are more interesting projects out there which I could attempt. I have heard of people making generators from motors, for example. However, winding a transformer is my primary goal. I have attached pictures of the motor. Please tell me whether the above mentioned transformer is feasible. Sorry for the picture quality. Thanks in advance.

Topic by TheLightningConductor 


Need a cheap dual-output, center tapped, 180VA 18V 5A transformer?

I am trying to design a nice dual-rail lab power supply and need a cheap dual-output, center tapped, 180VA 18V 5A transformer. The outputs are as follows: Primary: 120V Secondary 1:  9V-0-9V, @ 5A max. Secondary 2:  9V-0-9V, @ 5A max. ======================OR==================== Primary 120V Secondary 1:  9V, @ 5A max. Secondary 2:  9V, @ 5A max. Secondary 3:  9V, @ 5A max. Secondary 4:  9V, @ 5A max. I prefer a transformer for the linear regulator over a switching preregulator, because a switching preregulator sort of defeats the whole purpose of making a nice, high precision, low-noise lab instrument. However, I also prefer to have more than just 2 separate 18V outputs, since that means when the output is shorted and constant current mode kicks in for either the positive or negative rail, I will have a voltage drop of 18V, at a maximum current of 5A, and thats over 90W of power dissipation!!! I think that I can deal with that if thats the only solution, since I am planning on using a large CPU active heatsink for cooling, but I prefer if I was not pushing a TO-247 device to it's thermal limits. I have found this: http://www.antekinc.com/as-2218-200va-18v-transformer/ It is affordable, but it seems strangely cheaper than a lot of other toroidal Xformers on the market. Also, the 2 primaries are not center tapped. It is 200VA though! I have never heard of that company, and it seems like the description of it is written in chinglish. They act like the fact that they over-engineered and under-specced it is a feature (to me, thats how all ratings should be, that should be normal and standard, not a feature.). I have also found this: http://www.digikey.com/product-detail/en/36-6/36-6-ND/1984766 It would be perfect, but it is $80!!! Very expensive, Also, I do not think it is a nice toroidal transformer, not that that matters much to be, I just like the professional look of a beefy toroidal transformer inside a power supply. Lastly, I have found this: http://www.mouser.com/ProductDetail/Hammond-Manufacturing/1182G18/?qs=sGAEpiMZZMvwUzoUXIIvySPCJQuQgm7bYNfLdl9rdUYluBT2%2f%252bFqzw%3d%3d It seems to be very similar to the first find, and it is from a reputable distributor. At $70 it is still expensive, and I do not want to spend over $100 for a homemade power supply. I would just get a off-the-shelf solution for that! What about the possibility of modifying a MOT transformer? How many VA or watts can I expect from the output without active cooling? I know they are rated from upwards to 1000W, but I also know they cannot sustain that power output for a long time without overheating and requiring lots of active cooling, and from what I remember, I believe the core is really being pushed into saturation during normal operation, leading to LOTS of power loss in the transformer core, but can they output 180VA continuously and effectively? Approximately how many turns of wire would I need to achieve my requirements, and what gauge wire should I use? I am thinking 20AWG but someone who has done that before would know better than me.

Question by -max-   |  last reply


high capacity joule thief/dc-dc converter

I'm trying to make a dc-dc converter with the following characteristics: Output = 5V regulated at up to 30mA = 150mW Input 1V (or lower) from a slightly flat AAA. Assuming a pessimistic circuit efficiency of 50%, then the input current would need to be 150mW / 0.5 / 1v =  300mA which I think a AAA is capable of supplying. I'm using a variation of "led torch circuit 2" from http://www.talkingelectronics.com/projects/LEDTorchCircuits/LEDTorchCircuits-P1.html, but I've replaced with the 1n4148 with a schottky diode and replaced the 2 LEDs and 29R resistor with a 5k6 and 1k resistor respectively; this should limit the output of the circuit to just under 5v. I have a 150R resistor to provide a 30mA load to the circuit. When the input is 2.4V, the output is 4.62V which is close enough to 5v for me.  But if I decrease the input voltage to 1.14V, then the output voltage falls to 2.7V which is not enough. I have tried half a dozen hand wound transformers with various turns ratios, wire thicknesses and shapes (slug and toroid) but am unable to achieve 5v out (at 30mA) from 1v in. Does anyone have any suggestions as to what to adjust, or perhaps a better circuit?

Topic by GrotBox   |  last reply


Induction heater using the famous mazzilli vladimiro flyback driver?

After being done with 555oscillators and other hv projects. i am now interested with induction heater. i have seen multiple schematics on how to make them. However the parts needed are expensive. there was a similar question posted last year but did not have enough information etc. i have seen some people making the induction heater with the zvs driver of mazzilli, but did not give enough information on how to make it.  i need to wind 8+8turns on a flyback transformer core and 4 turns of thick wire one the other side to give more current. 1. can i wind the 8+8 turns on a toroidal core instead of a flyback transformer core(i don't want to break it even if i have more than 5) 2. for the capacitor 0.68uf. can a big 10uf 400v~ capacitor be used instead? or should i use 3X 0.22uf 400v~ in parallel so that it don't over heat due to high currents? 3. Will 2X 12v 35Ah car battery in series be enough to power the driver? i mean, will it drain the battery too fast which will lower its life span or should i use a rewound MOT?  4. Will a 2500uf 50v capacitor connected across the power supply be needed to smooth the current or will the circuit run finely without it.

Question by ARJOON   |  last reply


Tesla Coil Safety?

My high school recently had an engineering fair, and my friend had built a tesla coil. Its has multiple spark gaps, an RF filter (I think thats what its called), a 120 to 20000v transformer, and toroid top-load, if any of that matters. We/I would entertain ourselves by standing away from the coil and holding a fluorescent tube (by the glass with bare hands, not by the contacts) near the top-load and watching it light up. Even though I was well away from the coil, my forearm muscles would twitch, especially it the coil spark hit the contact on the other side of the tube. Then if anybody touched me, both of us would feel a shock and the same slight twitching (the same kind of twitching you feel from those electric muscle stimulators with the pads you put on sore muscles). We even set up a chain of about 5 people holding hands, and all of us would feel a shock, even though only the first person in the line (aka me)  was holding the fluorescent tube near the coil, with my hand on glass, no where within range of the streamers coming from the top-load. Now for my question: is this dangerous? (I know its non-lethal, im talking about my nerves) And what exactly was happening? because it was not an incredibly large coil, and i know that the field of a coil is much larger than the actual streamers. I also read somewhere that insulators dont work the same at incredibly high voltages. I think what I was feeling was the skin effect, and the charge came from the excited electrons in the tube. If my ideas are correct, then wouldn't me holding the tube be just the same as if i had just put my hand near the top-load and let the streamers hit me?

Question by masterbuilder   |  last reply


9kV 50mA tesla coil NST question. Why does the circuit breaker in my home trip when i plug in my NST?

Please someone help, this is my first tesla coil project, my setup: 230VAC 50Hz input ricci 9000v 50ma NST with a built in GFI (ground fault interrupter) but i bypassed the gfi succesfully .see pics safety gap  7,5 cm diameter pvc secondary 1000 turns #24 magnetwire (0,5mm) secondary 10 turns 8mm copper pipe primary (tapped at 7 turns) saltwater capacitor 16 green beer bottles in a bucket with a capacitance of 0,0122 uF or 12,2 nF (thegeekgroup bucket cap) static spark gap 28mm diameter stainless steel spheres as electrodes with oven fan (temporary, i am building a hyperbaric gap) 10cmx27,5cm aluminum toroid topload with a brass screw as breakout point RF ground aluminum rod 1,2 meter  When i tested the coil for the first time the spark gap was set on 6mm and i got 20cm or 8inch streamers without breakout point but the gfi on my nst tripped after a few seconds. i didn't know there was a built in gfi on my nst so i fooled around with my spark gap and safety gap and the tapping point on the primary hoping to get better performance. after a few runs the gfi started to trip very fast and i could only run the coil with the spark gap set on max 2mm, any bigger then that would trip the gfi on the nst. so i found out that it had a gfi and i bypassed it with thick wire. Then when i ran the nst i got the exact same thing but with my circuit breaker in my home. i have made a video on youtube that shows the problem here is the link: (please help) http://www.youtube.com/watch?v=piH44ohowyE please anyone help me! Any help or suggestion is very welkom!

Question by colinbarnes   |  last reply


Need help with making an amplifier

First of all I am only considering to make this amplifier I have not gone out and brought any parts yet although I have had a look around. If all goes well I will post an instructable of all the stages required to construct the amplifier.  I am looking to make an amplifier to be used with my computer and various other devices. This is the amplifier schematics I have had my eyes on.. I am new to all of this really but Ive been trying hard and eager to get this working.  Amplifier http://www.circuitstoday.com/2-x-60-w-audio-amplifier-circuit  I have designed this on Eagle PCB, need to double check the connections. Would be useful for some info on the width of the tracks as this was the element I was most unsure about. I am new to Eagle PCB so im not familiar with standard conventions and tricks.  Pre-Amp http://www.circuitstoday.com/passive-tone-control-circuit I have designed this on Eagle PCB, on a separate board again need to double check the connections.  Power supply  I Have got a basic 35v+/- dc supply schematic, it is based on a toroidal transformer, will probably need a inrush current circuit doing later. I have added the power supply components on the same board as the main amplification stage.  Frequency Crossover I have an idea of what I want to use, I was think a 2 way 2nd order Linkwitz Riley filter because I dont want some of the areas of the midrange to be lost, from what Ive seen on graphs, the low pass and high pass dip significantly closer to the crossover frequency. Ive selected some drivers that I liked. The tweeter has an impedance of 8ohms and a frequency response from 1.6khz to 20khz. The woofer has an impedance of 8ohms and a frequency response from 30hz to 4hkz. I read somewhere that it was ideal to crossover exactly in between the two i.e 2.8khz, let me know if you think otherwise.  Also Ive read up a bit on L-pads, would it be suitable/ worthwhile in this application? is it necessary to have the impedance seen by the amplifier constant, if so where it be? Ive looked up the components on a website supplying crossover and audio devices, there are many types of inductors and capacitors I am not entirely sure which type would be most suitable.  If somebody could help me out in designing the amplifier and understanding how all the circuits could come together I would really appreciate it. I  would definitely do an instructable of the construction of all the stages of this amplifier. Thanks in advance. 

Topic by Jarez Patel   |  last reply


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.

Question by -max-   |  last reply