Hello,

I hope that this qualifies as a new topic.

I have just posted a video to YouTube:

                                    http://youtu.be/PbG7KUeEGXY

I have attached the circuit. This shows how I modified a Joule Thief circuit to charge a bucket capacitor (1000uF) to a controlled voltage in the range 1 to 1.5 Volts which enabled a very low battery to power a typical battery electric clock.  In this example it was found possible to power the clock with a battery showing 0.7 Volt with a current of a couple of milliAmps.  I am not claiming that the circuitry is optimum and the number of turns on the toroid could be experimented with.

All of the components were obtained from my local Maplin store, (a chain in the UK,) but none are in any way critical.

I think that this could extend the application of the Joule Thief circuit to situations where an intermittent current is supplied from a bucket capacitor.  I think that it may be possible for much larger capacitors to be used although a limited battery may take longer to charge them.

The clock application is almost perfect for this circuit and it may be possible to make a long lasting solid battery from cheap materials yielding the necessary 0.5 to 0.7 volts at a very few milliAmps which would run a clock for a very long time.

I would be delighted if another enthusiast could reproduce what I have done.