Make a Joule Thief

Step 2: Wind the Toroid

The first step is to wind the toroid. I found mine in an old computer power supply, and it works fine for me. Toroids are donut-shaped objects like in the picture, and can be attracted by a magnet.

You can find toroids in a few places. Old computer motherboards, XBOX and X360 motherboards have them (don't take them unless it's dead!). You can find toroids in computer power supplies, or you could buy them at your nearest RadioShack.

Take your two strands of wire, and twist the ends together. You don't have to do this, but it makes winding a little easier.

Thread the twisted end through the toroid, then take the other two ends (Not twisted together) and wind it once around the toroid. Don't twist the wires; make sure that two wires of the same color are not right next to each other.

Keep winding, making sure you wind the coils tight. It will still work if they are kind of loose, but it is better to have them tight.

Ideally, you want about 8-11 turns on your toroid. Even if you can fit more, don't put more on. Make sure the turns are spaced evenly around the toroid.

Once you wind around the whole toroid, cut off the extra wire, making sure you leave a couple of inches for soldering.

Strip some insulation off the wires, then take a wire from each side, making sure they are of the OPPOSITE COLOR. Twist them together, and then you're done with the toroid.

Comments

[123awsomelad]

Can you just use a straight ferromagnetic core? or does it have to be a toroid?

[adien gumilang]

yes i can, but i just curious, i found these on my small electric motor, then i think, can i substitute the toroid with this?
um.. forgive me, i just a beginner

[adien gumilang]

can i subtitute the toroid with the same-shaped magnet ?

[Malkaris]

I've been playing with this for a little bit and I've had 0 luck getting the LED to light with the setup explained. However, I put a 1uF cap across the 1k resistor and it worked.

I can't figure out what is could be different in my setup that requires the cap.

Any thoughts?

[sconner1]

Looking for a torroid?
Take apart a burned out spiral lightbulb.

[Vick Jr]

Does anyone know where the "8-11 turns" of wire comes from? Is this from trial and error or Is there an actual equation where you plug in the I/O voltages, current, frequency, inductance, etc. and solve for the number of coils? (I like physics and ideal models.) : ] Knowing a formula like this could also help people optimize for using different power sources, LEDs, transistors, and torroids.

[poza]

your question is a year old, to be sure, but i'm working on a somewhat similar electronics project and i stumbled across your question while looking for answers to my questions. i have no knowledge on this subject and i'm in the process of learning as i go. i found a formula that mentions the number of turns around a toroid. you might check this out: http://www.mantaro.com/resources/impedance_calculator.htm#toroid_inductance

[lukedwards]

Thanks for the explanation! I thought I knew but wanted to double check and your instructions are in plain English and very easy to understand. Wish some people would take a tip from you and include this in their instructions instead of assuming everyone winds toroids everyday.

[kenmneth]

its a game to keep people living in fear. i use this second computer for people that might play those games if infected i just go buy another one for one hundred dollars at the nearest pawn shop.

[kenmneth]

is it possible for you to call me at 603-606-1171 ken

[gizander]

Dudes, we should be so lucky where i live to even have a place to get any electrical/electronic (almost) part/component that we need (even it is from "Rat Shark" haha! I cant find inductors for a radius of 150 miles...mostly just salvage or wind my own air cores if i need it "fine tuned"...BTW, are the guys at RS as ignorant as the salespeople at my local electronics shops? I was having trouble with a pinout for a Q and the owner of the shop couldn't tell me E from C (internet was out...have a nice pinout sheet now...it's here if you're interested: http://hamradio.lakki.iki.fi/new/Datasheets/transistor_pinouts/) Anyhow, the Real reason i'm leaving a comment is...just in case any of you have an '88 Compaq PS, theres a nice 1 inch or so (OD) toroid nicely prewound in there in blue and brown--9 turns exactly. It's thick gauge wire (16, im thinkin') so it should be strong. There are also 2 beefy lookin' toroids in there (1 1/2" odia and 3/4 inch wide!!!) and it really isn't as hard as it looks to take the enamel dunked copper off them. ... lotta good caps there, Rs and power Q's too (With the required heatsinks =)... I suppose if you dont have a junk '88 Compaq, something from the era of R.E.M New Order will do as well...lol. Cheers all! And thanks for the great 'iables 1up man!

[cynical_chemical]

so... what kind of household objects can i get a toroid bead from?

[akinich]

a cfl bulb

[Earths_hope]

DVD players! they hold the circutboards together.

[Questioneverything13]

Compact fluoro lights have them.

[1up]

"You can find toroids in a few places. Old computer motherboards, XBOX and X360 motherboards have them (don't take them unless it's dead!). You can find toroids in computer power supplies, or you could buy them at your nearest RadioShack."

[pdumont]

You can also find in the CFL the necessary wire to wind the toroid. There is a small black coil right off the AC line. Unwind the coil and there is more than enough wire to make the coil. I wound my coil full and it is working like a charm. Double the wire,twist both ends, when full be sure to wring out the wires and proceed with instructions. Good luck

[acmefixer]

Radio Scrap wants eight bucks for a small bag of a few toroids, and you have to unwind the heavy wire, but that's not hard. Go to www.Mouser.com and get some Fair-Rite 2643002402 medium permeability or 2674002402 high permeability cores. I forget, but I think a hundred of them is either $6 or $11 per bag.

[M4industries]

Haha! Radio Scrap!

[Father Christmas]

I find Radio Crap easier to say.

[1up]

Or Rat Shack. :P

[grampafish]

crap shack

[realtico]

Radio Shark! it bites your wallet!

[Possum Living]

Shady ol' Racket.

[cynical_chemical]

oh.. i found one in a compact flourescent bulb!

[the_lark]

You can also get 'em from RC li-po chargers. Some even have two toroids inside , a big one & a smaller one. Perhaps you'll find them in wall adapters as well.

[DELETED_Noah feasey-kemp]

(removed by author or community request)

[1up]

Any size will work, but I didn't know they had different densities. I'm assuming the densest would work best, or an uncolored one.

[DELETED_Noah feasey-kemp]

(removed by author or community request)

[1up]

Usually OK, if you wind your coil better it should work even better.