latching reed switches

[rustycoupler]

does anyone know, if i power a led with a watch battery for a passenger car could i use this to turn it off and on? also would it stay on until i pass the magnet over it againto shut it off?

[MisterBeasley]

Yeah, that's the general idea.

The reed switch is simply a toggle switch, generally single-pole, single-throw.  A "latching" switch will stay the way you put it.  A non-latching switch will revert to the OFF position once the magnetic field is removed.

[cacole]

Yes, a latching reed switch is all you would need if you have the correct voltage battery.  A latching reed switch turns on and off according to which way you pass the magnet over it; i.e., one direction turns it on and the opposite direction turns it off.

[nedthomas]

Latching reed switches come in two types. One is mechanical where the external magnet moves the reed over a center toggle and reversing the magnet resets it. The other uses a second magnet as "bias", i.e. the second magnet is not powerful enough to pull the reed but can hold the reed close after the external magnet closes the switch. Reversing the enternal magnet over powers the "bias" and the reed opens. You may be able the build your own using the "bias" method.

[dbodnar]

I covered the various options to turn LEDs on and off (including latching reed switches) in an article I wrote last year.

Have a look

http://www.trainelectronics.com/LED_Articles_2007/LED_103/index.htm 

 Let me know if you have any questions.

 

dave