Joule Thief

[gauschor]

Amazing work, conrad! Since you are able to light a 5 Watt thing, and all by this circuit you posted above?

What I am interested in is: did you try to attach a small e-motor instead of the light as a load? (the small common motors you have in remote toy cars for example).

[conradelektro]

@Jeanna,
Thank you for the hint on the glue, I will try that.

This “Jule Thief” thread and the two threads
http://www.overunity.com/index.php?topic=8341.0 (Joule Thief 101) and
http://www.overunity.com/index.php?topic=6942.0 (Joule Thief Circuit Diagrams, Etc....)
help in a big way if one wants to learn the art of Joule Thieves. Reading is important, but I only made progress when I went into actually building Joule Thieves. Then all the readily given help started to make sense. Participation in the relevant threads AND doing it myself were the way forward.

@Detrix42,
When I “tuned” the toroid  FERROXCUBE TN 23/14/7 I saw that with a 3 turn bifilar L1 + L2 and a 4 turn secondary L3 the circuit swung with a frequency of about 138 KHz (near your desired 175 KHz). I am not an electronics engineer, but I conclude from my experiments that one can reach the 175 KHz with a very few turn bifilar L1 + L2 (may be two turns) and a very few turn secondary L3 (4 turns).  But the circuit will be badly tuned as far as gain on the secondary L3 is concerned. The 4 turn L3 only gave about 1 Volt per turn at 138 KHz, look at the two “tuning lists” which I posted one  page up
http://www.overunity.com/index.php?topic=6123.13455 Reply #13458 on: May 07, 2010, 07:24:56 PM).

The big problem with frequency in a simple Joule Thief is that one can not stabilise it, it will go up and down with the temperature of the components (transistor, toroid) and the Voltage of the battery and also depends on the load on the secondary L3. A more complicated circuit with a quartz or timer will be necessary which is beyond my capabilities.

But some talented people know how to do that: http://www.youtube.com/watch?v=vm-G4GMsloI (here you see the Lidmotor 555 Timer CFL Light, frequency is stabilised with a timer, not a Joule Thief, but related)

@Gauschor,
The Joule Thief gives spikes (over collector-emitter of the transistor or over a secondary L3) and these spikes will be of little help to drive common electric motors (DC-motors or the brushless motors which need a nice 3 phase Sinus wave form).

But I saw that gifted people are driving strange pulse or window motors with a Joule Thief type circuit. But again, this is beyond me:
http://www.youtube.com/user/Lidmotor#p/a/u/2/AZyawAoxPfs (This is a small electronic pulse motor using a Joule Thief circuit).

Greetings, Conrad

(attached my latest 50 mm = 2” 1100 turn PVC evacuation tube air coil which I will “tune” soon; the photo shows only the long secondary L3 to which I will attach various types of L1 + L2 including pancake type coils; but it will take some time; may be not practical for a pocket flash light)

[electricme]

@All

Just had a phone call from Freepow (he carn't access the net at the moment) telling me about his latest JT experiment.

I have permission to mention the toroid is actually 2 toroids, not one, they are stacked one on top of the other.

He said the LED light can be unplugged from the JT box and plugged back into the town power if required without any modification, so I think what we all have here is the first "duel" power source for a LED light.

The JT section in the grey box has all the necessary parts so the LED light can be taken on a camping trip away from "normal power supplies", it runs on 2 nicad batteries which are recharged from a solar panel.

FP mentioned it is just about as bright on the JT as it is on town power.

Excellent work Freepow.

jim 

[electricme]

@conradelektro,
Power stabilsation, you could insert a LM317 adjustable IC between the battery and the JT, this will stablise the power to the JT. There are 3 legs on this IC, a voltage input, voltage output and the adjustable leg which takes its juice levels from the output side. Once set, it will pass only what you want it to pass through to the device, in this case the joule thief itself.

The advantage is, you can put a much higher voltage as the supply, it is also a power filter device to boot.

Hope this helps

I'm impressed, nice work done with the vertical aircore toroid, looks a very nice pic, while tuning, try holding a ordinary graphite rod vertically, then slowly inserting it, see what happens to the frequency, you will be "tuning" it.

jim   

[jeanna]

Great work freepow.

Ahem... Maybe not the first.
This one uses an unmodified LoA led bulb in a lamp or 2.

I called it the JTPU = joule thief power unit.
It is pictured with 2 AAA for extra brightness and will run 2 lamps each using a 20 led LoA bulb.
Plug in one or two lamps.
Flip the light switch for on or off.
With a pair of D cells, it has lasted over 2 weeks with no dimming.
I use it in my camper every night for 3-5 hours.

jeanna