We found these circuits in a 90s Radio Electronics. In them, we have the way to turn a load on and off using pressure switches. The circuit can be used with other types of direct current load.
This circuit is from an old American documentation. In it we have a simple way to fire an SCR from...
This experimental telegraphic communication system can have wires connecting to the handset of...
In the original 2000, this circuit was designed to interface the parallel port with external...