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.
The frequency of this oscillator depends on the capacitors, being able cover the range between 1...
This circuit can be using in demonstration to teach how light sensor, such as the LDR, can be...
This alarm with automatic shutoff was found in the April 1975 Radio Electronics magazine. The...