Found in a 90s American documentation, this circuit mimics the Enterprise warning signal from the movie Star Trek. The signal must be applied to an amplifier.
This circuit was found in an English publication from the 80's. It triggers a buzzer (with...
This is an amplifier stage with a typical germanium transistor from the 60's to the 70's. The...
This circuit was found in a Motorola Manual of 1965. The circuit has neon lamps as trigger...