This two-microphone amplifier was found in a April 1961 Radio Electronics Magazine. The circuit is powered by battery and has a 600-ohm line output.
With this circuit it is possible to add a conductance scale to a common multimeter. The circuit was...
With a touch of S1 this circuit keeps a small strand of nichrome warm enough to light a cigarette....
Mouser Electronics has in stock the MUSBR robust connectors for USB 30 applications from Amphenol. These...