Transform Audio/Visual Receiver into Adjustable 3-Phase Power Supply (.PDF Download)

If you need an adjustable three-phase, 60-Hz power source, a standard consumer audio/visual (A/V) receiver can be converted into a fully functional three-phase power source. By doing so, for example, a 100-W/channel receiver can supply up to 200 W by adding a simple adapter to the amplifier section of an A/V receiver, which converts it into a three-phase supply with corner-grounded open-delta output. CAUTION: Lethal voltages may be present in the output circuit.

To accomplish this, two low-level 60-Hz signals having 60-degree phase difference are required (Fig. 1). The first signal is obtained from the 5-V secondary winding of a small isolation transformer (Bel Fuse/Signal Transformer model ST-2-10); the second signal is obtained from the output of the all-pass filter, which has a 60-degree phase shift, with the output leading the input.