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.
This TTL circuit with the 7493 makes the binary count of the pulses sent by a flip-flop with the...
This circuit has an accuracy of 1%. The components used must be precision as well. The input...
In the figure we have a circuit that fires from a positive pulse of short duration applied to its...