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DSC Power-832 Tech Note (siren output gives low whoop all the time)

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Robert L Bass

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Oct 13, 1997, 3:00:00 AM10/13/97
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PROBLEM: Several people have mentioned the following problem with the
Power-832 -- a low whooping sound coming from the siren horn. The sound
is sometimes barely audible, but it is definitely present.

CAUSE: The Power-832 supervises the siren/bell output circuit by passing
a small, constant current across the output terminals, much like the
current in alarm zone wiring. If the circuit is interrupted (i.e., the
wire gets cut), the Power-832 gives a tamper output. Unfortunately, some
siren drivers and some stand-alone sirens are very sensitive and will
give a low level alarm sound from this "trickle" of current.

SOLUTION: Place a 1K-Ohm resistor across the [+] and [-] bell output
terminals, in parallel to the siren itself. The resistor will bleed off
enough of the current to silence the siren, but allow it to give a
proper response when the high-current output is switched on during an
alarm event. AFAIK, the 1K-Ohm resistor will not interfere with proper
operation of the supervision function.

DSC says they will modify the circuit in the next revision so this won't
be needed.

Hope this helps....

Blue Skies,
RLBass
.............................................
. Bass Home Electronics .
. 80 Bentwood Road, W Hartford, CT 06107 .
. http://www.BassHome.com .
. Voice (860) 561-2020 | Fax (860) 521-2143 .
.............................................

Mark

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Oct 14, 1997, 3:00:00 AM10/14/97
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Minor note on that, many times the system is fine during installation,
but the problem you mention will not show up for several weeks/months
later.

Sirens SHOULD be supervised anyway.

Irv Fisher

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Oct 14, 1997, 3:00:00 AM10/14/97
to Mark

Didn't DSC have a similar problem years ago? Thought I heard of this one
before. Same fix too.

C. Reid

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Oct 16, 1997, 3:00:00 AM10/16/97
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I am not trying to tell anyone how to do their job, but did you put a
1K resistor in the bell circuit?
Colin

Irv Fisher

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Oct 16, 1997, 3:00:00 AM10/16/97
to C. Reid

That is the fix. And DSC did have an identical problem years ago. But we were
told then we were using crappy sirens--and we believed it. In fairness, we
didn't see many of them either.

Zolotarev M.Y.

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Nov 29, 1997, 3:00:00 AM11/29/97
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> On Tue, 14 Oct 1997 21:03:05 -0400, Irv Fisher
> <iii.f...@sympatico.ca> wrote:
> >> >PROBLEM: Several people have mentioned the following problem with the
> >> >Power-832 -- a low whooping sound coming from the siren horn. The
sound
> >> >is sometimes barely audible, but it is definitely present.

The cause of this is small current, which monitoring siren circuit. Some
type of sirens can sound due this current.
The solution can be: 1. Change type of siren.
2. Add resistor in paralel to siren (resistor shoud be plased near
siren).
S.Y. M.Y.Zolotarev

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