The pentode tube used in this circuit has 1.5 V filament. The circuit is a voltage amplifier with the 1U5 tube.
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...