This AC mains-operated bistable switch turns on or turns off a device using a miniature neon lamp and a few discrete components. This switch can be used for control pan-els, appliances and lighting controls. A push-to-on switch is used to light up the neon lamp. The light emit-ted by the neon lamp, in turn, enables the switching action of the circuit. Use of a 555 timer wired for bistable operation makes the circuit act as a bistable switch. Circuit diagram : AC Mains Bistable Switch Circuit Diagram The neon lamp (NL1) and the push-to-on switch (S1) are directly connected to 230V AC mains. The 12V DC supply for timer 555 (IC1) is derived from 230V AC mains through capacitive dropper C1, resistor R1 and a 12V zener diode. IC1 works as a flip-flop circuit, with the signal at its output pin 3 toggling every time it receives a pulse at its pins 2 and 6. The operation of the circuit is simple. When you press switch S1 momentarily, the neon lamp glows, making phototran...