This circuit is from the 80's but uses common components today. The relay is voltage sensitive according to the power supply used. Transistors may be general purpose types.
This simple medium wave receiver was sold in the 1960s in Japan. The circuit used germanium...
This simple circuit makes use of neon lamps to indicate the voltage of a power grid. The lamps are...
This frequency divider circuit that generates a ladder-shaped signal was found in the June 1968...