This detector with ultra-low deviation was found in an American documentation from the 90s. Operational amplifiers are from that time. The power supply must be symmetrical.
Found in an Elektor from the 90s, this circuit simulates a rotary switch that provides a BCD...
This buzzer with the 555 was suggested by a Popular Electronics from the 90s to be used as a...
This circuit triggers on a lamp when the sensor (a metal plate us touched). Up to 100 W...