Switch off, Curcuit on

[Brendan w.]

I was building this project when i came to this problem,
i needed the make a switch that will turn the curcuit on when the switch is off.

I probably could find it somewhere but i don't have alot of time...
          I thougt it would be simple to find it but i can't seem to find it.

If you can give me a simple diagram of something like that i would really appreciate it.

Thank You

 

[tofarley]

I'm looking for something similar as well. I have a circuit that uses a motion sensor. Typically, the output from the motion sensor powers the base of an NPN transistor. For my project, I would like to power the circuit when the motion sensor *stops* registering. Not to say the circuit should run continuously (in which case I would simply substitute a PNP) The circuit should activate once, to operate a solenoid, whenever the motion sensor stops sensing. I'm hoping for an analog solution to this problem.

Any assistance would be greatly appreciated!

 

[audioguru2]

Brendan,
Just buy the switch.
A double-pole switch has two separate sections.
A double-throw switch has two positions.
Get a double-pole, double-throw switch then one section can turn on something while its other section turns off something.