I have Relay which I control via my Arduino.
The relay is responsible to switch-on an equipment, which must not be shut down/start (basically toggel its previous state) when the arduino either mal-functions and turns off or is turned off accidently by some user.
So the requirement is to be able to mantian the last state of the relay even if the arduino is powered off. How can I achieve this.
Many thanks
RaT.
There are relays which conserve their states (bistable, latching).
As long as you have power, you can use the relay to power itself if it has an extra throw on it that you are using. Connect the NO side and common of your relay in parallel with the triggering circuit. Once it triggers, it will close, giving power to the coil until you break the current flow to the relay somehow. I recommend a button so you can force it off.
This won't work if the system loses power though.
Search for "latching relays".
Rob