Found in a Popular Electronics from the 90s, this circuit activates a recorder for automatic recording of telephone calls. The circuit was used with old cassette recorders of the time.
The circuit used is the 4093 configured as an inverter in this application from Radio Electronics from...
We find this circuit in a 1977 technical documentation. The circuit generates signals in a wide...
In the figure we have a way to obtain a 15 V symmetrical source with a 30 V single winding...