IT HAPPENS TO ALMOST EVERYONE that an apparatus or system should have been turned off a moment ago. The device in question could be the car heater, the air conditioner, the lights ...
This Design Idea offers a solution to the challenge of turning devices on or off in the past. In Figure 1, I[C.sub.2] is a 555-type timer (preferably CMOS) connected as a monostable one-shot multivibrator. The pushbutton switch, [S.sub.1], triggers I[C.sub.2]. You can replace [S.sub.1] with a transistor or an optocoupler, for example. You can connect [V.sub.OUT] to a relay or a transistor, if needed. You might need to adjust the values of [R.sub.4] and [R.sub.5], depending on the output load ...