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 UHV generator circuit or ultra-high voltage was found in a 90s Electronic Engineering 90s. The triac...
When the sensor is activated the relay turns on powering na external load such as a buzzer siren...
This transistorized receiver was manufactured in the 1960s and distributed worldwide. The diagram is...