This is an integrated clock circuit from the time and was published in the November 173 Radio Electronics magazine. The circuit uses an AE7218 as a base for restorers.
With the shadow over the sensor, it is possible to interrupt the sound of your amplifier using this...
This circuit provides a signal when dialing occurs. The circuit is powered by the telephone line...
We found this circuit in a 1995 documentation. It can measure frequencies from 100 kHz to over 100 MHz...