This circuit is for old telephones with analog lines. It was found in the May 1988 Radio Electronics magazine. The circuit is powered by the line signal voltaje.
The circuit shown can be used to send command pulses from a cogwheel or other sensor placed...
Using a 741 operational amplifier, this circuit amplifies very low voltages, allowing its...
Nixie-type displays are no longer used except for assemblies of people who like old technology. The...