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[leo]

Good job Robert .... Mystery Solved ! Any
idea how much you want to build another one? :-)

ps. Does the relay shut off the circuit after
the alarm is disactivated? I assume all the
power source is from 12V battery, so it is
safe, right ?

leo

[Brian H]

Sounds good.

[Robert D]

When the internal alarm stops the rectified
voltage is gone and the fet turns off
letting the relay drop out thus external
siren turns off. I Use a 12volt 500MA plug
in power supply to power the relay circuit
and the siren. It stays powered all the
time so that when the bridge rectifier sees
the signal, it turns on the relay which in
turn switches on the siren. I used four
1N4007 Diodes For the Bridge.The Fet is an
N Channel $1.99 (RadioShack) and the relay
around $8.00 at Radio Shack.I assembled
components on a perf board and enclosed in
plastic box.

[iceblue]

Robert, the modification to which you speak
is of great interest to many in this forum,
including me.  Unfortunately, most of us are
not very electro-mechanically inclined.  I
have posted two step-by-step modifications
for the door/window sensors (Sentrol 5150
glass shock sensor and Jim's smoke detector).
When you get a few moments, would you please
consider writing a step-by-step instruction
(and parts list)for us on the internal-to-
external alarm modification.  Please note
that it is easiest to first write the
instructions in MS Word or Notepad, etc.,
and then cut and paste (in reverse order)
into this forum thread.  This will save you
time and minimize any frustration of long,
multiple postings into this forum.  Robert,
thank you very much for your consideration
of this request.

[leo]

i have better idea. If it works, can u
tell us how much you want to sell it for? :-)
you can start your own business this way.

leo

[leo]

i have better idea. If it works, can u
tell us how much you want to sell it for? :-)
you can start your own business this way.

leo

[Robert D]

 
EXTERNAL ALARM FOR 49-1000

PART LIST
all from Radio Shack

1. Diodes        5   1N4003  4 is for
bridge, 1 is to put across relay
coil(protects FET from
Voltage spikes)
2 . Capacitor   2     .1@50v  1 across bridge
output and 1 across fet gate to source
3  Trimpot       1    20k ohm  Radio Shack
may have this in mixed assortment bag.
4. MOSFET    1   IF510 Radio Shack has this.
5. Relay           1    12v dc relay  Radio Shack
6 12 Pwr Sup   1    12v dc power supply with
at least 500MA out ( I used 1AMP)
7. Siren            1     Any 12vdc siren
within current limits of pwr sup& relay
ASSEMBLY
1.Open 49-1000 and solder a pair of 24 awg
wires to piezo sounder in
Parallel with the existing ones. Route wire
pair thru  one of many holes in back cover
then replace back cover on 49-1000.
Use a piece of perf board to assemble parts on.
2. Make a bridge rectifier with 4 of the
diodes(if not sure how, get a tech book)
3. Connect the 2 wires from alarm to the ac
in on the bridge rectifier.
4. Connect a .1 capacitor across + and –
output of bridge
5. Connect the 20k trimpot across + and –
output of bridge also(cw &ccw)
6. Connect one end of a 1k resistor to wiper
of trimpot.
7. Before fet is put in circuit, put a
voltmeter plus lead on wiper of pot and - lead
To – bridge. Trigger the alarm and adjust
the output to 15vdc at the pot wiper.Turn
alarm off and Continue assembly
8.Connect open end of 1k resistor to gate of
fet.
9. Connect one end of a .1 cap to gate of fet
and other end to minus of bridge.
10 Connect source lead of fet to minus of
bridge also.
11. Connect a diode across the coil of the relay.
12. Connect the anode side of the relay coil
and diode to the drain of the fet.
13. Connect cathode(end with band) side of
the relay coil and diode to the +12 volt
Power Supply
14. Connect minus side of 12 power supply to
minus of bridge.
15. Also connect +12 volt to a contact on
relay that is normally open.
16. Connect the wiper for that contact  to
the plus on the external siren
17. Now ground the minus side of the siren
back to the bridge minus.
Assembly is now complete

[Robert D]

It does work, I have it in use now.
Sorry, I do not want to make them for sale!

[iceblue]

Robert...Thank you so very much for taking
the time to write out your modification and
for sharing it with us!!!!!!!!!!!!!!!!!!!!!

[iceblue]

Robert...Do you see any reason why this
modification cannot be made to the PH508
Powerhorn Siren?  As a PH508 siren
modification, it would allow running far
less interior cabling in the house for the
external siren...I could just put a modified
PH508 siren in the attic and run the cabling
for the external siren from there?  Please
advise, if you have a moment.

[iceblue]

__PH_508__Power_Horn_Siren

[Brian H]

Since the PH508 has 4 sounders to be driven
by the output circuit. You may need to
change a part or adjustment to get the 15
volts on the adjustment pot. May check that
on a PH508 as I still have to retest for the
Pigs relay mod in the other thread.

[iceblue]

Thanks Brian...I really don't know anything
about electronics but I have a soldering
iron and the desire to fabricate (I am
learning I have to be careful about what
parts can take heat, etc.).  I can't design
anything as I don't understand tolerances,
impediances, voltages, etc. But, if I know
what parts are needed and a general idea of
where they go, then I will give it a try.
Thereafter, I can write a step-by-step for
novices such as myself and post it here.
So, I greatly appreciate your efforts as
well as Robert's because I cannot figure it
out myself.  But maybe in the future....as
each mod forces me to read more and more
about electronics and each successful mod
lends confidence as well!

[Robert D]

I don't know anything about the PH508 or
powerHorn to advise

[Robert D]

I don't know anything about the PH508 or
powerHorn to advise