Most watchdog-timer ICs produce a single limited-duration output pulse when the watchdog timeout expires. Some applications, however, require the output to latch. This simple circuit provides a ...

Figure 1a shows a latching circuit based on an optocoupler, IC 1. If the off switch remains closed, pressing the on switch powers the LED in the optocoupler. Thus, the transistor in IC 1 turns on. You ...

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 ...

Many varieties of ON/OFF control circuits use some form of flip-flop that responds to a pushbutton switch or other control input. These all have volatile memory and default to an OFF condition if ...