Finally, a full version with 4 batteries! It has a 6-filar coil (4+2). The way the transistors are used there will never be a short-circuit. It's self-oscillating at 570Hz but the batteries are unfortunately going down quite fast. There is tuning and you name it to be done. Edit: bad soldering and some diodes to capture the spikes was missing.
Get the circuit at: http://sites.google.com/site/nilrehob/