Phone circuit (CB8709E)

With this circuit, found in a 80s Popular Electronics, it is possible to use two ordinary phones in a basic intercom.

Low Frequency Converter 4538 (CB25388E)
This converter was found in the June 1991 issue of Radio Electronics magazine. The circuit uses...
Field Strength Meter with FET (CB12498E)
This simple field strength meter was found in a 1970 publication. The zero-adjustment...
Pre-stabilization circuit (CB8802E)
Found in Philips' 1968 documentation, this circuit serves as a 6.3 V reference for high stability. |...