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 8 years ago  |  last reply 8 years ago


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 10 years ago  |  last reply 10 years ago


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 8 years ago  |  last reply 8 years ago


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 9 years ago  |  last reply 9 years ago


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 10 years ago  |  last reply 8 years ago


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 6 years ago  |  last reply 6 years ago


Is this a Toroid Bead and can it be used for a joule thief? Answered

I found it at the end of a power chord.

Question by coolpizzadude 9 years ago  |  last reply 8 years ago


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 8 years ago  |  last reply 8 years ago


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 8 years ago  |  last reply 8 years ago


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 4 years ago  |  last reply 4 years ago


How to wire this thing?

Hey Guys, Recently I bought a toy taser. After opening it and carefully observing it i accidentaly broke some of the connections. Can any one guide me on how to wire this capacitor/toroid or whatever this thing is? And will supplying 9v instead of 6v make the output higher?

Question by SA-DIY 3 years ago  |  last reply 3 years ago


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 9 years ago  |  last reply 9 years ago


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 9 years ago  |  last reply 2 years ago


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 9 years ago  |  last reply 6 years ago


need help winding toroidal transformer

I'd like to know how to wind a torodial transformer with a toroid that I just happen to have. I would like it to work at 60Hz at 120 volts (US mains) and have an output of 36volt centertap (18-0-18) or maybe a little less (I'm building an op-amp powersuppply that gets regulated to +-12volts) and as many amps as possible (well, safely). The toroid I have is painted a light green with a blue ring on one side. it is 1.25" outerdiameter, 0.75"innerdiameter. It's 0.5" thick. It looks like the bottom left toroid in the picture below, just bigger and no wire. I do not know what gauges to use, how many windings (well, I know the ratio), how many amps it can deliver, how I should wind it, etc.

Topic by guyfrom7up 10 years ago  |  last reply 9 years ago


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 5 years ago  |  last reply 5 years ago


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 6 years ago  |  last reply 5 years ago


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 11 years ago  |  last reply 11 years ago


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 8 years ago  |  last reply 3 years ago


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 9 years ago  |  last reply 9 years ago


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 5 years ago  |  last reply 5 years ago


How many more times do you have to wrap a ferrite rod to achieve the same power as a toroid bead?

So recently I found a neat low-voltage fluorescent driver instructable, it calls for a large toroid as its inductor, I dont have any large toroids, but I do have a ferrite rod.  What I want to know is if I have to wind 90 turns of wire on a toroid, how many do I have to wind on the rod?  I know it has to be more because the rod looses EMF through its ends.                                                                                                                                   thanks in advance,                                                                                                                                                             Junits15

Question by junits15 9 years ago  |  last reply 9 years ago


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 8 years ago  |  last reply 8 years ago


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 8 years ago  |  last reply 8 years ago


Cannon printer motor 24v Answered

What is the use of this toroid here?

Question by sooraj619 7 years ago  |  last reply 7 years ago


My joule thief is not very bright? Answered

My joule thief is not very bright? I've changed the windings, transistor and the resistor; and it is still pretty dim. Help please Parts: 2 different size toroids: Large and Small 3 Transistors: 2n2222, 2n3904, 2n5830 2 Resistors: 1k, 2.2ohm blue led white led with a heatsink Also I used a 20awg and 36awg to make the toroids

Question by daemonral 9 years ago  |  last reply 9 years ago



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 6 years ago  |  last reply 6 years ago


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 9 years ago  |  last reply 9 years ago


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 5 years ago  |  last reply 5 years ago


How does the joule thief circuit work? Answered

The best i can figure, the current coming through toroid turns on the transistor, then the collector drains the current to the negative, while pulling it from the emiter back through the diode to the collector? if i am correct, how would this boost the voltage?

Question by revelae 9 years ago  |  last reply 7 months ago


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 7 years ago  |  last reply 6 years ago


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 8 years ago  |  last reply 7 years ago


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 3 years ago  |  last reply 1 year ago


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 8 years ago  |  last reply 7 years ago


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 10 years ago  |  last reply 10 years ago


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 7 years ago  |  last reply 7 years ago


How do you increase the amps from a joule thief? Answered

          I'm working on a project using the joule thief circuit and when I put multiple LEDs in parallel they all get really dim. Is there anyway I can increase the amps going to the LEDs so they can all shine brightly?                                                                                                                                                                                       I was thinking a more powerful transistor or a larger transformer toroid with more windings. Any suggestions?                                                                                                                                                                                                                                                                                                                                        Here is a link to the circuit diagram:                                                                                                                     http://www.evilmadscientist.com/article.php/joulethief                                                                                                                                                                                                                                                                       Thanks!

Question by transistorguy 8 years ago  |  last reply 6 years ago


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 4 years ago  |  last reply 4 years ago


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 4 years ago  |  last reply 4 years ago


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 9 years ago  |  last reply 9 years ago


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 9 years ago  |  last reply 5 years ago


Looking for help with making a coils

I am wanting to make a rodin coil, like the second picture I included, except I don't have a 3D printer and I don't necessarily feel like dropping $200 on buying one and learning how to use it just to make a coil. So I'm asking if anybody would want to 3D print, ABS is fine, a Rodin coil for me? I have a PayPal account so we could work out a mutually agreed-upon price and I'll pay for shipping. I will also cover the the shipping cost. 76five, for6O, fourOsix9 shoot me a text ( that's my Google Voice number obviously I wouldn't give out my real cell phone number LOL)

Topic by DonS165 6 months ago  |  last reply 6 months ago


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 10 years ago  |  last reply 9 years ago


Matching impedance from ear out to line on soundcard?

I'm transferring old audio cassettes from an old cd-deck without line-out, so I have to use the ear-out for the signals to my soundcard's line-in connection. I am educated in electronics as Raidio Offiser, but that was in 1976. I'm also a hamraidio-operator since 1980 so I have made many transformers with toroids, building transmitters. Well that is a long time ago so it would be nice to taking up the hobby with building electronic devices again. I am from Norway and we don't have a lot of companies like Radio Schack. I don't now any now. In 1980 it was lot of dealers, but after Internet came, all uses that to communicate. Best regards from Thor Andersen Drammen Norway. thor.3043@getmail.no

Question by mirum 7 years ago  |  last reply 7 years ago


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 4 years ago  |  last reply 4 years ago


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 9 years ago  |  last reply 8 years ago


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 9 years ago  |  last reply 9 years ago


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 2 years ago


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- 4 years ago  |  last reply 4 years ago