Maglite small bulb question for all you EEs

[Kermy]

Got 2 questions for the engineers out there
1. I want to hook up this: Mag Lite Bulb to a programmable logic controller. The thing of concern is this, how do I hook it up? Can I hook it up directly with say...5 volt input into one end and the other end to ground? Do I need to put a resistor in series like with LEDs?

2. For BOTH LEDs and bulbs like these if I was to change the voltage around, does it go slowly dim or does it suddenly go out?

Thanks guys

 

[NutBucket]

You *should* be able to drive that bulb with digital logic but you should put in a resistor since it says not to use more then two cells to drive it (3V). Or you could get fancy and use the logic to bias a transistor to drive the bulb but maybe that's a bit advanced for you?

LEDs will dim to an extent before they just stop working but it won't be nearly as much as a bulb.

 

[cressida]

You'll probably need some resistors

 

[Kermy]

Erm, darn link didn't work properly. It's the bulb for the Mag Lite 2AA flashlight. Does it matter which feet I hook up to ground? Also, what resistor do you think I should use?

Thanks,
Kermy

 

[LordSnailz]

How do you determine how big of a resistor you need? Just one that would give you a 2V drop across it?

 

[attahoova]

whats the nominal resistence across those bulbs?

 

[Colt45]

you could just use 3 Si diodes, they will drop 0,6v x 3 = 1,8v. close enough.



or, if the logic IC doesnt have enough output to run it, put the 5v through a resistor to the base of a transistor, have the collector to one side of the lamp, and the other side of the lamp to earth.

have the emitter going to B+.


The size of the resistor between the logic IC and the transistor will change the amount of current the transistor will allow to flow through the lightbulb.


uh.. IIRC. solid-state is my weakpoint.

 

[attahoova]

Originally posted by: Colt45
you could just use 3 Si diodes, they will drop 0,6v x 3 = 1,8v. close enough.



or, if the logic IC doesnt have enough output to run it, put the 5v through a resistor to the base of a transistor, have the collector to one side of the lamp, and the other side of the lamp to earth.

have the emitter going to B+.


The size of the resistor between the logic IC and the transistor will change the amount of current the transistor will allow to flow through the lightbulb.


uh.. IIRC. solid-state is my weakpoint.

yeah I don't think the IC is gonna drive enough current safely for that bulb.