This variable frequency oscillator for radio transmission covers the range from 1.6 MHz to 20 MHz, depending only on the coil used. The circuit is very stable and can be used in amateur equipment.
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...