This circuit is from the 80's, using an integrated of the time. The circuit serves as a reference, as this type of dialing is no longer used today.
Found in a 1964 magazine, this is a small headphone amplifier from 500 ohms to 10 k ohms (magnetic...
This is a basic astable circuit using the 555 IC and driving two LEDs. The phase on a rate giving...
The frequency in this circuit is adjusted by P1 and given by C1. Short pulses, as the ones...