We found this frequency meter circuit in a 1974 documentation. The circuit is powered by 12 V and has 8 digits. Changes can be made using a prescaler to reach higher frequencies.
This circuit monitors the voltage of a 12 V battery. The indicated levels let you know if the...
This 3-channel configuration was found in a 1982 Selezione Radio magazine. The publication no...
Signals from old cordless phones can be picked up with this circuit. L1 has 10 to 20 turns of 32...