These are 12V DC power supply circuit which designed without transformer (trafo). These circuit use capacitive reactance instead of resistance; and it doesn’t generate very much heat.The circuit draws about 30ma AC. Always use a fuse and/or a fusible resistor to be on the safe side. The values given are only a guide. There should be more than enough power available for timers, light operated switches, temperature controllers etc, provided that you use an optical isolator as your circuit’s output device.
Warning!!! : This circuit is potentially dangerous! If your electricity comes with a “live” wire and a “neutral”, the neutral is usually connected to the earth. Sometimes there is no neutral at all and you have 3 phase wires, with 115V to 240V between two phases. If you form a conductive path to the earth and you touch one of those phase (“live”) wires, this can be lethal!
Only work on a project like this if you know what you are doing, this is nothing for beginners!
