Hi, Please have a look at the circuit at:
The circuit it to turn on or off a AC bulb by a microcontroller. My question is, can we somehow safely add a manual override switch near the bulb, so that even if the microprocessor is not working, we can turn the switch on/off manually? If yes, how will the circuit then look like? Sorry if this is a simple question as I am just starting in electronics and electrical circuits.
You put a switch in parallel to the relay contacts.
Sure. This is a simple question that involves basic technology of a bulb, a switch and a power source. Given that this has risen for you as a problem, I'd complete the rest of the exercise NOT using mains line voltage until you are certain that it does indeed work. Get someone qualified to check your electrical work.
Adrian C wrote: we can
Ah sorry, didn't see that bit. What I suggested would only allow manual switching to the on state IF the microcontroller had it switched off.
You need a three position switch
Position 1 - off Position 2 - uProcessor Controlled Position 3 - on
You can use a single pole, double throw, center off switch, like this:
o---[YourRelay]---+ AC ----o | o-----------------+ | [Bulb] | AC-------------------------+
In the off position, the AC is not connected to either pole of the switch.
Ed
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