This telegraph monitor was found in an American documentation for radio amateurs from the 1970s. The indicator is a common 1 mA full-scale milliammeter.
This circuit was found in a Signetics documentation from the 1980s. Next to the figure are the...
This circuit was found in documentation from Analog Devices from the 90s. The circuit uses...
This sophisticated decade of benchtop resistors was found in the November 1989 issue of Radio...