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.
The circuit we present was found in an English magazine from 1980, but it can be easily assembled, as...
We found this circuit in an American documentation from the 90s. The circuit produces a 1 kHz...
By activating S1 the relay closes its contacts only after a certain time interval that depends on C1....