Found in American documentation from the 90s, this circuit uses a high voltage relay and has no grid isolation. The high values of R1 and R2 prevent the shock when it touches the sensors.
This transistor source has the output voltage selected by zeners and the LED indication of which...
This filter can use almost any common operational amplifier and needs a symmetrical power source. The...
This receiver, called Peace, was manufactured in the 1960s in Japan and was powered by a 9 V...