Using a varactor or varicap, this 1969 Electronics World circuit has a modulation range from 75 kHz to 52 MHz. Modern equivalent components can be used.
We can either supply this circuit with 12 V if we use a relay for this voltage as well as 6 V if...
Two NAND gates are used in the configuration shown here to perform as a monostable triggered by...
Frequency and active cycle of this circuit are fixed by the two crystals that may have different...