Joule Thief With Motor Coils

Want a Joule Thief circuit in a slim shiny package? Scoring serious geek points is high on the agenda of the forward thinking tinkerer, and what better way to do so than with the recycled innards of a floppy drive, toy motor or precision stepper? None Spring to mind... So with that ..in..mind.. Lets get on with it.

This project is basically a "Joule Thief" but with more scrap parts reuse and unfortunately less efficiency. The basic Idea is to use the core of a motor as both the "toroid" part of a "joule thief" (with the rest of the circuit concealed in and around it) and as a nice light reflector (which , if you have access to a pancake motor, is conveniently reminiscent of a flower or the sun).

As previously stated it is very inefficient, and the reason I chose to do it this way is that it uses an otherwise scrap part as a functional and decorative component. Obviously, if you so choose, you can put a hand wound toroid in but it will probably require a bit more room than is easily available so you might lose out on Prettiful Points. If you want to go with a normal joule thief circuit I recommend 1up's excellent Instructable here. Since the Circuit build has already been covered many times before I will focus in on reusing the motor and quickly cover the rest of the circuit. If you need help please leave a comment.

For a few more pictures and discussion please see my blog post

Step 1 Bill Of Materials & Equipment

Materials
1 x 1k resistor
1 x NPN transistor (the 2N3904 is adequate, however 2N4401 or PN2222A will give better light output)
1 x LED
- x Enamled Copper Wire (0.315mm is fine)*
1 x Reasonably sized electrical motor. DC and stepper motors are both fine.

*(other insulated wire should work fine, I used this and it looks OK)

Equipment
Soldering Iron & solder
Needle Nosed Pliers/tweezers
Screw driver
Ohmmeter/Multimeter

Comments

[AGT563]

All right Andy here's the comment you suggested that I should post, slitely defferent though because I felt I should share more info on the subject of joule thief's. The efficiency of the joule thief could be improved by winding your own coils it's time consuming and a pain in the but to remove the existing coils but I find winding my own coils often yields good results. I made a transformer the size of a penny and got 18 volts dc from a 1.5 volt AA battery and that was just by connecting and disconnecting it to the battery by hand, it is a pain but making your own coils is worth it.

[drakesword]

Very interesting idea for a joule thief. Good for recycling old motors (like case fans)

[andy]

Hi,

The range of stepper motors in even one computer (floppy (2 motors), CD drive (2 motors), Hard drive, case fan, CPU fan, power supply fan) is quite surprising, it was due to having an over abundance of old computers' mismatched motors that I became interested in reusing them for something.

My favourite stator is found in laptop CD drives - it is a small, flat pancake stepper that works very well with the joule thief circuit, and makes a compact and very flower like device.

With regard to your other comments, thanks for the terminology corrections. As previously noted I have been unable to find any consensus on the names of the variously structured stepper motors - I just made some names up because in this instructable they only serve as points of reference to aid hacking. I do appreciate terminological corrections and think that they are useful as comments.

One thing to note is that comments don't attach to a single step, only to the instructable. It's clear from your messages what you mean, but just for future reference that's how Instructables lists comments (that confused me a few times when I joined too).

Thanks,
Andy

[drakesword]

actually they do attach to steps, but they are all listed as one on the first page. if you click the delta page only my comment will show up!

[andy]

Ha..I had no idea!

Thanks again,
Drew

[drakesword]

I believe this is known as delta (hence the triangle shape)

[drakesword]

Note I posted this on the "Ring Configuration" page

[drakesword]

I believe this is called Wye (where it looks like a Y)

[drakesword]

Note I posted this on the "Common Configuration" page

[drbill]

That floppy drive stator when built to catch and turn with the wind will produce electricity.
I am looking for more disk drives to do just that but they are kind of hard to find in Hawai'i cause everyone has the latest of everything here it makes me sick.

When I find the next drive I will take the thing apart more carefully. The screw that holds the disk that holds the magnets has Lefthand Threds. Hindsight is 20/20.

I will be very interested to know when the strip magnet is replaced with more powerful tiny magnets from harddisk drives, how much electricity I can harvest from such a tiny stator.

[andy]

As far as I know, any magnet based stepper motor will be capable of producing electricity when rotated. The trick is working out the wiring and applying rectifying and smoothing circuits.

If your looking for a small generator there are many alternatives to floppy disk drives - anything broken with motor actuated parts (personally I have reused motors from toys(dc), motors from printers, scanners, record players, walkmans, tape players, CD and DVD drives, servos and many others). Hard drive disk motors are very well made and well worth scavenging. If you find anything broken and electrical it is rewarding to take apart, if for nothing else than to see how it works, and how it's made.

I too have come across counter intuitive things like "backwards" threads and 3 spoke Philips heads, and other puzzling design decisions. The hardest dis-assembly that I have done was a (broken) office laser printer, which had multiple concealed redundant retaining clips and screws.

I have wanted for a while to make a mini portable generator, possibly a VAWT (Vertical Axis Wind Turbine) and it's low down (getting higher) on my "future projects" list.

Regards,
Drew

[Dream Dragon]

This does look like a really good way to build a joule thief. Just a note on terminology, it does vary, but the "Ring" configuration you mention, is also called "Delta" and what you refer to as "Common" may also be called "Star" configuration.

[andy]

Hi,
Thanks! Yeah I had trouble with the terminology, in that I found lots of names for different connection graphs. In the end I just made up some names for the various topologies based on how they look - I figured that it would be easier to understand if I just gave each a name and stuck with it.

Thanks for your input,
Drew

[lemonie]

Easier to wind than a toroid, nice post.

L

[acmefixer]

PNP 2N3904??? The 2N3906 is the PNP version. I think you meant NPN. But it would be brighter if a 2N4401 or PN2222A were used.

Other shielded wire?? I think you meant insulated wire.

[andy]

Thanks for the corrections and recommendation acmefixer, I have changed the errors on page one. I described using the 2N3904 simply because that's what I have to hand, and never got round to investigating alternatives.

I think your right about swapping out the 2N3904 for something beefier, but I can't see having four transistors in parallel being very good looking, the problem of holding components in place becomes more of an issue if you are free forming. Having said that if it makes it work it makes it work.

Thanks for your input,
Drew

[westfw]

Interesting idea. (pretty. I've been staring at motor guts for a while trying to think of something functional to make with them.) I suspect it's inefficient because motor windings are designed NOT to magnetically interact with one another (as opposed to interacting with the rotor.) I wonder if one of the single-cell LED schemes that doesn't use a center-tapped inductor would work better. (like this Electronic Design article )

[andy]

I was thinking something along the same lines... One of my "queued" projects is to try to run a Nixie tube off a particularly large stator (from a printer) using a bus pirate as the source of the PWM signal. I'm currently still doing things with my rotary screen but once I get round to it I'll report back here with my findings.

Thanks,
Drew

[acmefixer]

A single winding coil circuit like the one in that link would work. But the 2N3904 is a weak little transistor with a chip that's half the size of the 2N4401 and is overworked in a Joule Thief circuit. It works but the light output is substantially lower. I just got a brainstorm. Put four - or maybe more - 2N3904s in parallel for even more visual impact. By the way, if builders are concerned about the battery life, they can increase the resistor to 3.3k or even more, to cut down on current - but with less light output. Or else use my Supercharged Joule Thief Flasher circuit.