Can be built around a center tapped 24V control transformer or 2 separate 12V transformers since inductive coupling between primaries is not required. The capacitor across the secondary may need to be adjusted to get the frequency of oscillation you desire.
Update: in this version the low gain inherent in transistors handling large currents is offset by using Darlington devices instead of plain BJTs. This reduces the power that would otherwise be lost in base resistors having to carry large base currents, however the transistors still need to be installed on a heatsink.
This circuit can cause serious electrical shocks. Use caution and avoid running the circuit without a load as the output voltage can double or more. Even if you aren't hurt, the overvoltage can destroy some transformers.
