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 two-tone buzzer can be powered by a solar panel. The circuit is from a 1991 documentation. The...
This blocking oscillator was found in a publication from the 50's. The coils determine the...
The TPA3100D2 integrated circuit from Texas Instruments (www.ti.com) consists of an efficient...