I have been trying to make an underground vault for my base and have decided to use observers, i am trying to have pistons constantly out that can be deactivated by removing fire, but i cant make the observer keep a constant signal, so i used repeaters and they make it so the system wont turn off anyone know how to make an observer emit a constant signal?
The observer itself can't keep a constant signal, it just gives a short pulse everytime there is a change to the block in front of it.
You can make a redstone toggle that turns on every other time it gets a signal and turns back off every other time, but you can't make the observer tell the difference between removing the fire and relighting it, say, so you run the risk of the circuit getting out of sync and turning on when it's supposed to be off and vice versa.
Another problem is that the observer seems to detect changes in the flames and give extra signals every once in a while so I'm afraid your idea isn't likely to work.
If you can use command blocks they might be able to do the job otherwise I don't know what you can do besides using something else as a switch.
For instance, a repeater behind a wall can detect if you place a redstone torch in a special spot, or there are setups with hoppers that can detect if a special item is thrown onto them and won't pick up anything else.