Found in American documentation from the 1980s, this circuit makes use of components of the time, which are uncommon today. The circuit detects the approach using a sensor formed by metal plates.
This inverter bistable buffer circuit was obtained in a Hands On of the 90's. Next to the circuit we...
We find this circuit in a Popular Electronics of the 80's. The frequency range depends on C1 and...
Suggested by a Popular Electronics from the 90s, this circuit triggers an external load, relay or...