This 1965 circuit uses a Philips 4068 tube to measure extremely small charges. The circuit has as indicator a micro ammeter and the transistors are of the time.
Also suitable for use as a noisy alarm, this Morse Code or telegraph practice oscillator was found...
This circuit makes simultaneous control of two up to 150 W incandescent lamps. The circuit is half wave...
This circuit was found in an old documentation from Europe. The integrated circuit used is...