When the phone rings, a high-powered incandescent light comes on. This circuit can be interesting to obtain the remote call warning or to assist the hearing impaired.
In this circuit the capacitor under test is charged at switch position A and then discharged...
This is a common circuit in the 1990s, when experimental FM transmitters were in vogue. The...
Using a piezoelectric sensor of the time, this circuit was found in the February 1994 issue of...