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.
We found this circuit in the 1982 Selezione Radio magazine in Italy. The circuit uses an...
This circuit was obtained from Dutch documentation from 1967. It uses transistors of the time...
This circuit was found in a 1966 General Electric book. The triac and the day are from that time...