Found in a 1964 Electrronic Design, this circuit is intended to control analog video signals. The circuit has an attenuation of 45 dB at 20 kHz.
This circuit uses a photocell as sensor and a sensitive relay according the power supply voltage....
This circuit was obtained from an English magazine from 1977. It is a toy musical instrument that...
To small metal plates are used as sensor in this circuit. The skin resistance is enough to trigger the...