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 is a circuit from the time when some still called the transistor a crystal triode. It...
This circuit, suggested by General Electric, increases the sensitivity of a common multimeter to 1 M /...
This indicator, shown in the figure and suggested by National Semiconductor, causes an LED to...