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.
This circuit was found in a Radio Electronics of July 1984. It consists of the traditional 1 A...
This circuit is from a 90's Radio Electronics. The circuit operates accurately up to about 15 kHz...
I found this circuit in an old British magazine from 1976. It is possible to test operational...