Can anyone identify what this circuit board would be used for? It was attached to an external wall of a residential property. I'm thinking it's part of a security system.

 

Too stupid for a security system
My guess is a lighted intercom, So;your right a "security system".

 

Would such a thing be mounted on an external house wall? I thought it might be a security screamer.

 

A better Idea is a strobe and screamer as you said. I looked at the pic on my laptop and the tubes are very likely strobes.

I can't see any identifying marking for the terminal strips or whatever connects to the outside world.

The chips might be LM555 timers?

 

Agreed. The tubes on the left are definitely strobes with the trigger wire soldered to the side of them. From the pic I can't really see anything else that would confirm it though.

 

Thanks guys

 

Welcome to AAC.

Given the two tubes on the left and what appears to be the back side of possibly a speaker or some kind of horn or sonic alert it's probably either a fire alarm or security alarm. Not sure what's going on here but it sort of looks like someone may have been pulling parts off this thing I would expect to see four diodes acting like a full wave rectifier, but given that there's only three here ? ? ? The larger transformer appears to be connected to the sonic alert or speaker or whatever it is,
so it's probably an audio transformer. To be sure we would need a much clearer picture of the board both sides and the whole unit front and back.

 

If we could see the rest of the pieces, and both sides of them, it would be rather obvious to some of us.
But here is a guess: Based on what looks like some sort of speaker plus redundant strobe tubes, it is probably the remains of a fire alarm system announciator. Those devices must deliver both audible and visual warnings to warn both deaf and blind folks that an alarm condition is happening. Is it part of some building wreckage? or what?

 

Smoke/fire alarms in hotel rooms frequently have a strobe as well as a beeper, so I agree with the strobes + siren security device. If you are thinking about firing it up, wear ear plugs. A big piezo blaster like that can do permanent damage in under one second.

ak

 

Devices like this usually have one PCB design for all versions, with only parts of it getting parts stuffed in and soldered.t is not reasonable to think that parts have been removed. Given the damaged condition of the housing it is not reasonable to do anything other than salvage parts from the board. Strobe tubes are fun to experiment with but do not apply any excess voltage to them, they do burst.

 

is not reasonable to think that parts have been removed.

Didn't say parts were removed, I said

it sort of looks like someone may have been pulling parts off this thing

Clearer pictures lead to clearer conclusions. And less arguing.

My first thought was fire alarm, but I didn't see enough of it to come to that conclusion. However, after seeing what others are saying, it might just be that, an out-door alarm. And it looks like it's been out doors for a while.

Again, back to those diodes - it could be AC powered with battery backup. Without more clarification, we're just guessing. And it doesn't make sense to argue about guesses. Yours is as good as mine. Possibly better than mine. But still, it's a guess and nothing more.

Also, I'm not seeing any clear evidence of a flash capacitor. There's ONE big cap but it "Looks Like" a 50V cap. So if that's a 50V cap then it's not a flash cap.