This 3-tube intercom was published in a Radio Craft from 1946. The power supply comes from the mains with a transformerless source. The diagram is for two ways, but the circuit can be adapted for more ways.

This 3-tube intercom was published in a Radio Craft from 1946. The power supply comes from the mains with a transformerless source. The diagram is for two ways, but the circuit can be adapted for more ways.