This approach alarm circuit was found in the September 1970 Radio Electronics issue. The 1 mH coil is wound on a ferrite rod. The relay is 12 V sensitive.
This VHF transmitter was found in Radio Electronics magazine from June 1964. The transistor is an...
This two-transistor circuit is from a Radio Electronics magazine from April 1965. The transistors are...
This circuit was found in a 1967 documentation. The switch diode is a component of the time and is...