How do I interface an old alarm system with no voltage contacts (no or nc) to a siren that needs 12

ElectricSpidey

Joined Dec 2, 2017
1,681
I don't know...the instructions seem pretty clear to me.

The "no voltage" statement only applies to the loop contacts, not the "relay" contacts.
 

Thread Starter

David Weaver 1

Joined Sep 1, 2019
14
I don't know...the instructions seem pretty clear to me.

The "no voltage" statement only applies to the loop contacts, not the "relay" contacts.
I agree as that is what I thought, and I am trying to find a way to use the "no voltage" NO contacts to trigger a 12 volt input to the siren/strobe when the NO contacts close. There must be a circuit that I could use!!
 

crutschow

Joined Mar 14, 2008
27,243
I agree as that is what I thought, and I am trying to find a way to use the "no voltage" NO contacts to trigger a 12 volt input to the siren/strobe when the NO contacts close. There must be a circuit that I could use!!
What NO contacts?
Again, the contacts you want to use are the "OUTPUT" contacts from the alarm to trigger a siren and those don't have a zero voltage limit, not the "INPUT" contacts from external sensors that do have the limit.
Do you not understand the difference between the two types of contacts? o_O
It makes no sense to have a 0V limit on the output contacts.
 

Thread Starter

David Weaver 1

Joined Sep 1, 2019
14
What NO contacts?
Again, the contacts you want to use are the "OUTPUT" contacts from the alarm to trigger a siren and those don't have a zero voltage limit, not the "INPUT" contacts from external sensors that do have the limit.
Do you not understand the difference between the two types of contacts? o_O
It makes no sense to have a 0V limit on the output contacts.
Thank you so much to everyone who responded. I am now fully aware that the contacts on the external output of the alarm control box set only output contacts.
Because of the alarm installation instructions I was just looking for a circuit that would make sure I did not overload these contacts. A circuit that allowed me to just use the NO (normally open) contacts as a trigger for a method to put 12 volts on the siren activation input when alarm went off.
Again thanks for all your help.
 

Thread Starter

David Weaver 1

Joined Sep 1, 2019
14
Thank you so much to everyone who responded. I am now fully aware that the contacts on the external output of the alarm control box set only output contacts.
Because of the alarm installation instructions I was just looking for a circuit that would make sure I did not overload these contacts. A circuit that allowed me to just use the NO (normally open) contacts as a trigger for a method to put 12 volts on the siren activation input when alarm went off.
Again thanks for all your help.
Hi,

Just thought I would let you all know that I spoke to Honeywell's help line today and they told me that an alarm box can be connected to the control panel as long as there is no voltage across the common and Normal Open contacts, when they are closed due to the alarm being triggered.
As the AG6 siren box would require a 12 volt signal to operate through the contacts, they say that it will not work with my control panel.
They are now searching to find a siren box that can be fitted to the control panel, although they have said it is a wireless system and may not be able to have an additional powered external siren box. ( The system came with a Solar powered Wireless external siren, which every winter loses power due to a low battery.)
So I am back where I started, I either find a circuit that can take the closing of the panel contacts, with no voltage on them, and will then trigger the 12 volts for the siren to operate when the alarm is activated.
Again thanks for all the responses.
 

Thread Starter

David Weaver 1

Joined Sep 1, 2019
14
IMAG1227~3.jpg
Hi,

Just thought I would let you all know that I spoke to Honeywell's help line today and they told me that an alarm box can be connected to the control panel as long as there is no voltage across the common and Normal Open contacts, when they are closed due to the alarm being triggered.
As the AG6 siren box would require a 12 volt signal to operate through the contacts, they say that it will not work with my control panel.
They are now searching to find a siren box that can be fitted to the control panel, although they have said it is a wireless system and may not be able to have an additional powered external siren box. ( The system came with a Solar powered Wireless external siren, which every winter loses power due to a low battery.)
So I am back where I started, I either find a circuit that can take the closing of the panel contacts, with no voltage on them, and will then trigger the 12 volts for the siren to operate when the alarm is activated.
Again thanks for all the responses.
While I wait for Honeywell to respond I have pulled the control panel apart and found only one relay.
IMAG1227~3.jpg
As it appears to be the only one in the system I think it must be for the external siren?
Will see if I can find a data sheet for it.
 

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be80be

Joined Jul 5, 2008
2,051
This is your most horn hookups lot's of cheap alarms cant switch more then a few mA
So the horn has a built in driver be it relay or electronic.
alarm3.jpg
 

ElectricSpidey

Joined Dec 2, 2017
1,681
“that an alarm box can be connected to the control panel as long as there is no voltage across the common and Normal Open contacts, when they are closed due to the alarm being triggered.”

If you place the NO & common contacts in series with the 12 volt supply and the siren, no voltage will appear across the contacts when they close. (unless it's defective)

Just be sure the supply can handle the siren, and isn't more than the relay ratings.

That statement really doesn’t make any sense to me unless they are worried about someone placing voltage directly across the contacts. (without a load)
 
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