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.
A frequency divider for digital signals can be constructed based on a single 4018 integrated...
This circuit triggers three incandescent light bulbs following the audio signal applied to its...
This traditional configuration was taken from na 90s American technical leaflet. The circuit...