The relay RY1 will be turned on when 12V dc supply is applied to the circuit. The transistor T1, and hence the relay RY1, is off when the control signal input J1 is 12V. Obviously, we need a ...

This is a simple clap switch circuit with high sensitivity. The only unusual component is the single coil latching relay. While there are numerous means of generating the latching function, the ...

5. The waveform during power on (a) and power off (b) indicates how the redundant circuit handles both the stuck-high failure of the power-monitor IC or short-circuit mode failure of the transistor.

The linked 555 article makes sense if you read it, but a normal NPN circuit to drive the relay only takes 1mA… easy for most uC’s. Then it starts talking about active low input, and how CMOS ...

Tiny Circuit Saves Big On Relay Power March 16, 2006 Designers frequently use special circuits to reduce the power required to hold a relay in the latched position.