This frequency divider by 10 uses discrete components only. Modern equivalent components can be used as the circuit is from an 80's documentation. Nearby frequencies can be used.
This circuit that uses only transistors indicates when the voltage in the circuit has the voltage...
This is the circuit of a robot published in the June 1992 issue of Radio Electronics magazine. The sensors...
This circuit was found in a 1980s documentation. It decodes by identifying a certain frequency tone...