This 1967 General Electric circuit makes use of an array of 3 (integrated) transistors for an amplifier stage. The circuit has a 500 mV output.
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...