This circuit, found in a 1958 magazine, is for reference only, since the components are not easy to find today. The transistors are germanium types and power supply is made by common cells.
The sensor for this alarm is an LDR and it consists of an oscillator that goes into action when...
This circuit was found in American documentation from the 90's. The transformer is of the high...
The circuit shown is a white noise generator using a zener diode as a source of noise. The...