Is that a joule thief?

[Groundloop]

Thanks again Groundloop.   Sounds like you've got a finely tuned JT there.   Thumbsup smiley here  (hint hint Stephan)

e2matrix,

This JT circuit is inspired by Dr. Stiflers work on the Spatial Energy Coherence (SEC) Exciter circuit.
Thanks goes to Dr. Stifler. I have two tuning components in my version of the circuit. The frequency
of the oscillator is set by C1 and L2 at the base of the circuit. And the oscillator frequency is very
constant over a wide range of input voltages.  R1 (1M Ohm) provide the voltage bias to get the
oscillator going. The L2 coil is flat on the circuit board and the L1 coil is mounted vertically. This means
that there is just a small L1 to L2 coupling. The end result is a oscillator that can be run on a wide
range of input voltages with a relative constant light output in the LED. The LED is also mounted
directly over the L1 coil so that the current through the LED is channeled back to the positive rail.
This will give a oscillator that uses very little current from the input. The LED I'm using is a ultra bright
blue 10mm diameter LED. The L1 and L2 coil can be found on the PCB of CFL lamps. All in all a funny
circuit to play with. I highly recommend people to study Dr. Stiflers work on the Spatial Energy Coherence
(SEC) Exciter circuit.

GL.

[Groundloop]

My JT battery voltage is now [25.04.2013 0620] down to 2,66 Volt. That is a drop
of 0,11 Volt in almost 14 hours. LED is no longer bright enough to be used as a night light.
Seems that the batteries is now close to almost no charge left. Will keep the circuit running
until LED goes fully dim to see how low voltage this circuit can run on. Oscillator frequency
is now at 467KHz.

GL.

[Groundloop]

My JT battery voltage is now [25.04.2013 1545] down to 2,61 Volt. That is a drop
of 0,05 Volt in approx. 9 hours. LED is very dim now, barley any light, but still visible.
Oscillator frequency is now 471KHz. Amazing stable during the various input voltages.

GL.

[Groundloop]

My JT battery voltage is now [26.04.2013 0645] down to 2,55 Volt. That is a drop
of 0,06 Volt in 15 hours. LED light is still visible, but very dim. Oscillator at 474KHz.

GL.

[TinselKoala]

Hi GL very nice work as usual.....

I love your spectrum analyzer display. What instrument is that from?  My lab is sorely lacking in that regard; I have been trying to obtain a spectrum analyzer plugin for my HP180a for some time now but just can't afford it.

I'm a little scared of your copyright notice.... May I please have permission to copy that schematic image of your Oscillator to my hard drive, for my personal use only?   

When it's finally too dim to see, I wonder what would happen if you warmed the batteries gently.....

Cheers, keep up the good work...
--TK