The purpose of this circuit is to measure the resistance of an antenna at the resonant frequency. The circuit is from an old American documentation for hams.
This simple half-wave control using an SCR, which may be TIC106, has been obtained from a US...
The circuit shown here can be used to produce low-frequency sine wave signals from CMOS logic. The...
This VFO was found in a 1980s documentation. The central frequency is given by the crystal and the...