Joule Thief

[jeanna]

Hi everyone,
I am charging the Nicad with the jtc secondary.
I just added a led at the basic jtc spot and it lit up, so then I checked the scope.
The scope shows a very very low sine wave curve with 12 v with the battery charging and 10v same shape with the led in place.
I will need to do a real test over time etc later, but I can light a led and recharge the Nicad simultaneously!!
It is set up like gadget's but opposite.

What is really strange about this is that I am looking at the secondary wires at the usual place, across them. Then beyond them, is a bridge with an additional diode at the pos and neg corners.
Then to the wires of the battery holder.

So, this is closing the circuit with the bridge and removing all the spikes that go high.
So, where is this 12v coming from?
It is reduced by 2v when I use one led, so the 12v remaining here seem to be "real".

This is pretty interesting.

More later.

jeanna

[jadaro2600]

I was able to modify this circuit into an astable multivibrator joule thief circuit.  here: http://en.wikipedia.org/wiki/File:Transistor_Multivibrator.svg by replacing R1 and R4 with small inductors and running the diodes off the collectors. Potentiometer up top.

It uses around 20ma ... I've been reluctant to test my trigger coils, I will have to do some soldering to get the terminals to connect to my breadboard - might as well do this all at once.

Lights LEDs pretty well, thinking about using trigger coils instead of the inductors.

[jeanna]

@jadaro,
This is cool.

This circuit should be blinking.
Did you get it to look steady?

Nice work!

jeanna

[jadaro2600]

@jadaro,
This is cool.

This circuit should be blinking.
Did you get it to look steady?

Nice work!

jeanna

Using very small capacitors, the lighting looks continuous.

edit:  By increasing the inductance on one inductor, I'm able to increase the voltage boost on the opposite side with a lesser inductance.  For instance I have a 10 uH inductor on one side and a 100 uH inductor on the other side ( instead of off positive, it's connected behind the potentiometer ).  The rectified voltage off the 10 uH inductor is 30V and barely lights an LED on the other side.

note, setup on the lossy side is altering the circuit to be more monostable, in this case it's an inductor on one side, and a resistor + inductor on the other.

The circuit is using 30mA now, seems this could use some improvement right now.

Also, I tried routing the diodes back to the beginning of the inductor so that the collapse didn't occur between negative and positive, instead between collector and positive, ..this seems to decrease the current consumed, but also drops voltage gains a bit.

The inital boost on a circuit with two 10 uH inductors, rectified, is 5.2 volts.

[xee2]

@ jadaro2600

I was able to modify this circuit into an astable multivibrator joule thief circuit. 

Another interesting circuit. Great  work. Do you know what the inductor values are. I would suspect that the larger they are the higher the C-E voltage will be.

EDIT: I see you answered in your edit as I was posting. Thanks.