Does anyone have any experience with these sorts of detectors that you'd get in older bell boxes? Or know how they worked?

I have just made one, using the most simple bits possible, two resistors, an LDR and a 2n2222 transistor. Did they work like that

a beam of light getting interrupted, or was it more advanced? Been testing mine, and I couldn't get it to false alarm at all.

 

Thanks,

 

Gabs 

 

IIRC "Viper foam detector"

 

pcb within plastic case, size of shock sensor

 

IR Led + Receiver below the case

 

Used to FA when the housing filled with webs or bugs ect...

 

Used to FA when it got dark after it had be powered up the 1st time

 

Google has no pics & I've not see one in yrs....

Yea, and the hex bells had optional paddles to detect foam, linked to a small switch on either side of sab. 

Thanks, I have one of the "Modern Alarms" bell boxes with these in, will get a pic. Well, mine didn't false alarm at all, during light tests I did, I'm impressed. I know, looked on Google for some pics. Don't know why they couldn't be as simple as the one that I made. Those Hexagon bell boxes were such a good design, shame they changed it. The idea of a foam detector is flawed anyway, by the time it has been squirted? in it would be too late.  

It's more for signalling. Audible only has always had limitations 

their was a foam pedant (cqr ?) which had magnet to keep in vertical, foam or a 1/2 a brick being chucked a the bell would knock it in to alarm

 

there has been all sorts of clever stuff, however the industry is very "price sensitive" 

Interesting, I understand, its easier and cheaper to buy a fully made up bell box now. Do you take many of these down? Or have any old stock of these? Would be interesting to see them. I like the fact that the internals of a bell box are on 24/7, 365 days a year, constantly for 20 years or more, never get a break. some very robust electronics. 

1 hour ago, Gabs said:

I understand, its easier and cheaper to buy a fully made up bell box now.

 

IIRC we started buying CQR Cequra's early 1990's, the 1st batch lasted forever....

 

1 hour ago, Gabs said:

Do you take many of these down?

 

I can't recall the last anti foam device I removed, 

 

I have an old bell module that came down earlier in the yr , I'll pop a pic sometime

 

 

 

 

This was removed the other week from a adaptable box in loft, oldest scantronic Digi i recall seeing

11 minutes ago, MrHappy said:

 

 

This was removed the other week from a adaptable box in loft, oldest scantronic Digi i recall seeing

So this was a bell module? In the loft? Looks to be in very good condition, do you take down many standard bell modules? like SAB modules?