Joule Thief

[Farmhand]

Yeah I realize that loss, and I try to adjust it so the ringing is gone and when I adjust it further to cramp up the wave form it raises the amplitude. And it's at that setting it seems most efficient, no ringing at all because no time for ringing. I adjusted it back just to reduce the power output but then the JT's boosted voltage became higher anyway  and the output from the second oscillator stayed just a bit less, not much, so better to run it without the ringing. The test coil is a ringy coil. That will be changed out for a smaller one.

Could probably run a low power micro there if the voltage could be controlled from the initial boost side.

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[TinselKoala]

"Ringy" is good because it means high Q which means small losses per cycle in the resonant ringing. On the other hand eliminating ringing by shortening the time between stimulating pulses is good because then you are approaching true resonant pumping, where a tiny push at the exact right time keeps a high-amplitude response going and this is not allowed to decay.
I think. Maybe.

[mscoffman]

A 74, 74LS, etc 5V series TTL or 4000 series CMOS will not work. 

The key to Dave Johnson's circuit is the ultra low voltage logic gate:  Digikey P/N   296-13169-1-ND  This is one gate in a package the size of an SOT-23 transistor but with five leads instead of three.

http://www.digikey.com/product-detail/en/SN74AUC1G04DCKR/296-13169-1-ND/484306

http://www.ti.com/lit/ds/symlink/sn74auc1g04.pdf

The device is rated for a power supply voltage down to 0.8V, but will go lower.

A 74x14 hysteresis inverter version exists too.

http://www.digikey.com/product-detail/en/SN74AUC1G14DBVR/296-12880-6-ND/1634643

[MarkE]

A 74x14 hysteresis inverter version exists too.

http://www.digikey.com/product-detail/en/SN74AUC1G14DBVR/296-12880-6-ND/1634643

One would have to experiment to see if the AUC14 works better at below spec supply voltage than the AUC04 .  The hysteresis of the '14 will probably make it harder to start oscillating.

[Farmhand]

Umm I scoped the base of the JT transistors base and it is going negative by almost 10 volts when the transistor is off !
What's the go with that - is that ok ? No wonder it lights the red LED backwards there.

Can I make use of that voltage to bootstrap the JT supply voltage some how ?

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