This amplifier with fixed AC bias was found in a 1947 documentation. The circuit uses two transformers in the power supply and two full-wave rectifier tubes.
In this circuit the relay triggers on when light falls onto the sensor, a common LDR. Power supply...
This circuit emits a warning sound when night falls. The circuit is from a Hands On Electronics from...
This circuit can measure capacitances in various ranges using a common analog indicator. The...