Found in a 1966 publication, this circuit is a simple version of a field strength meter. The diode is a general-purpose germanium type.
This 1 kHz circuit was found in American documentation from the 90s. The original operational...
This circuit triggers a remote doorbell when the phone rings. The circuit is for the 110 V mains...
This circuit was obtained from an American publication of the 80's. The integrated circuit is of the...