Joule Thief

[Pirate88179]

@ Cap:

Yes, I received your thanks via pm.  No thanks needed.  I got the first link from someone on here about 6 months ago.  From there, I found the others.  I was so happy to get this information then, and I am glad to pass it on now.  I believe that is what this site is all about.....or should be. We all should exchange knowledge when we can.

Bill

[Yucca]

Just some thoughts on this:

The thinnest wire I have is 30awg, I think if you use thinner wire then the average current consumption will go down and the LED will stay just as bright. If you want to use thicker wire then you can use more LEDs in parallel without upping current draw. The drive coil takes the current, the coil gauge needs balancing to the LED draw. If it´s too thick gauge then you use power and the LED won´t get any brighter.

I will try and unwind a cheap minispeaker coil out of a broken kids toy that I´ve seen kicking around the living room. I think maybe you could go REAL thin and up the number of turns a little on the drive side of the coil to make it much more efficient.

I have also had the thought of using the transistor case for the coil form using very thin wire with a superglue spot to start and finish the coil and decreasing the number of turns on the trigger coil to do away with the base resistor completely. Then it would just be 1 tranny, 1 LED and some really thin wire. Maybe the ultimate minimalist joule thief 

Yucca.

[Pirate88179]

@ Yucca:

Sounds good.  Go for it and let us know what happens.

Bill

[WilbyInebriated]

Just some thoughts on this:

The thinnest wire I have is 30awg, I think if you use thinner wire then the average current consumption will go down and the LED will stay just as bright. If you want to use thicker wire then you can use more LEDs in parallel without upping current draw. The drive coil takes the current, the coil gauge needs balancing to the LED draw. If it´s too thick gauge then you use power and the LED won´t get any brighter.

I will try and unwind a cheap minispeaker coil out of a broken kids toy that I´ve seen kicking around the living room. I think maybe you could go REAL thin and up the number of turns a little on the drive side of the coil to make it much more efficient.

I have also had the thought of using the transistor case for the coil form using very thin wire with a superglue spot to start and finish the coil and decreasing the number of turns on the trigger coil to do away with the base resistor completely. Then it would just be 1 tranny, 1 LED and some really thin wire. Maybe the ultimate minimalist joule thief 

Yucca.

heres some data on different cores and turns
http://www.prc68.com/I/LED.shtml#BO

[spinner]

Hmm, this circuit (a very basic transistor oscillator with an inductive coupling) is called "The Joule Thief"? Lol,  I can assure you it's more like a "Joule waster"...

Yes, it works with only a few (easy to get or make) components, but that's about all it can do...
It actually works as a (quite inefficient) DC to AC/frequency converter, wasting at least half of the Energy available.

Maybe it's the rather low input voltage where LED is still working that fascinates you?

There are serial (three/four pin "transistor like") components on the market, which allows you >85% efficiency (DC/DC chips, usually needing only a few external low-tech components to work). They all beat this circuit (in efficiency) at least by the factor of two... And they're still not Unity.

Joule Thief? Yeah, sure...