Joule Thief

[NickZ]

  It looks like it is an inverter circuit meant to run off of the grid, and convert to 12v output, I think.
  It uses two transistors to share the load, and dissipate the heat, and the 1k resistors are used to control the amp draw. So the circuit should also be fairly efficient. The led is an indicator led, and the 4.7k resistor is there to control over-voltage to the led.
So, this circuit is not exactly a Joule Thief. But, is possibly a grid to 12v inverter instead.
  Anyways, that's what it looks like to me.

[crowclaw]

I'ts a 12 volt DC to 220v AC inverter circuit, nothing special about it's design. In fact if you use an AC transformer with a primary to match your line voltage and a secondary centre tapped  at 10v - 0v - 10v it will work fine. the output is not quite sign wave but will power small AC loads,and yes sucks AMPS from your 12v DC battery.

[Dave45]

Its the wire gauges, the circuit is nothing special basically works like the zvs
Should be able to step up voltage in one direction and amps in the other.

You could probably us the zvs then smooth it out into dc, even into a dual rail
pull one side of the dual rail into a self loop, power components off the other side of the rail.

Just thought I would put it out there, Im working on a similar setup just a little more complicated.

[NickZ]

  quote:
  "Should be able to step up voltage in one direction and amps in the other".

  If it did you'd really have something, but it doesn't. Not in your posted diagram.
  It steps up the voltage in one direction from the 12v battery out (only), but, by sacrificing the amps, not by stepping up the amps. What "other" direction?
   The feed back path is something that we are still working on, it may be possible, but up to now it has not been easy to do,   for a reason.

[Dave45]

What "other" direction?

If you look at the primary circuit there are two transistors, think in electron flow from neg to pos, the transistors each fire a pulse into the outside of the double primary, the bemf from each turn on the gate of the other this causes the oscillation.

The transistor symbol is setup to show conventional flow but is not the way electrons move.

Basically this system is pulsing two primary's use the two primary's to step up voltage on one and current on the other.