Electrical advice - old fire alarm bell

[Perplexed]

I picked up this schoolhouse type fire alarm bell this weekend, and after some research, realized they could be set up for 110V AC, or 6, 12, or 24V DC. There are no markings anywhere on this alarm to indicate which it could be, other than the maker’s name. I was wondering if you folks might have tips on how to determine the proper input?

 

[kingfish]

The two coils are electromagnets. Since I see no rectification circuitry to convert it from AC (electromagnets only work with DC) then you are down to three choices. A dc variable power supply would be the easiest way to figure it out, but you probably don't have access to one. So you will have to use batteries to figure it out. Start with a 6v lantern battery. If that doesn't make it function or ring weakly, touch the wires to your car battery. If it rings like you would expect it to, then you have your answer. If not then it is either 24v or nonfunctional. be careful when using your car battery. If one of the coils is shorted, you could get a pretty big spark and it get hot in a hurry.

 

[zipty6]

That thing's cool. I hope you get it working.
I would have loved to have had one of those when my kids were still in school.

 

[montesa]

My guess is 24v.

 

[Perplexed]

The two coils are electromagnets. Since I see no rectification circuitry to convert it from AC (electromagnets only work with DC) then you are down to three choices. A dc variable power supply would be the easiest way to figure it out, but you probably don't have access to one. So you will have to use batteries to figure it out. Start with a 6v lantern battery. If that doesn't make it function or ring weakly, touch the wires to your car battery. If it rings like you would expect it to, then you have your answer. If not then it is either 24v or nonfunctional. be careful when using your car battery. If one of the coils is shorted, you could get a pretty big spark and it get hot in a hurry.

Thanks for the advice! I do have access to a variable DC unit, so I’ll try that.

 

[Bocephus123]

make great ring bells for wrestling and etc.

 

[Perplexed]

AC.

DC won't work.

Start at 24, if that doesn't work go to 48. Make sure the coils aren't open or shorted before you start.

Why do you say DC won’t work?

 

[KOPBET]

Why do you say DC won’t work?

B/C of the way it's built. Better pictures would be helpful.

 

[Bocephus123]

have 2 ill have to look at mine i thought 12v

 

[Bocephus123]

that company appears to still be in business in Brooklyn NY