Need help to service and expand "panic" alarm system

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Thread Starter


Joined Mar 17, 2013
Several years ago I set up a "panic" alarm system for some county offices which would signal the sheriff's department that law enforcement officers were needed at the location initiating the alarm. I now need to expand this from 3 zones up to 6 zones or offices. I would like to try and improve on the current display
method and then add possibly 3 more. What I have is three display "boxes" which have a red cover and
sirens inside. Each is labeled so that the dispatcher can see where the alarm came from. There isn't a whole
lot of room for these items so I'd like to use some smaller red (possibly LED) lights with siren and label them.
With 6 they will get pretty bulky and space consuming.

I'm thinking of some type of panel with the lights mounted in a hole and protruding through and a separate (if not self contained) siren or piezo sounder. The sounder could be just a single unit but wired so it will go off no matter which area created the "panic" call.It would be best for each to have a "test" button to simulate
an alarm trigger to show the display and sounder are working and a "reset" button. Right now, when an
alarm is sent, the light and sounder remain on until someone resets or cancels it at the dispatcher's desk.
(this is so if someone has stepped out of the room a minute or two that they will see the alarm as soon as
they return. ) The link below shows what I am currently using.... have three of these in a row and covers

Also would like some suggestions or help regarding the circuitry where I have a latching relay which keeps
the alarm display/sounder going until reset... will follow up with those details when someone feels they
would be able to help out.

Thanks very much!

Evil Lurker

Joined Aug 25, 2011
Seriously? Weren't those sort of systems phased out in like what, the early 90's? Basically nowadays if you are going to go through all the trouble of setting up a panic alarm you should ditch as much analog crap as you can and go with an embedded microcontroller. Ideally such a setup could be operated in something smaller than a shoebox, have an LCD or LED screen interface, be able to run off battery backup power for at leas 12-24 hours, perform self diagnostic an readiness tests, and function autonomously with as little human interaction as possible in the event of an an emergency. In my vision such a device would be able to determine the owner of the button immediately after getting the distress call, look up their address, name, and other contact information from memory, then use text to speech conversion to directly broadcast the alarm over the radio. In addition the contact information would be transmitted wirelessly to a small screen on the dispatcher's desk to eliminate the need to get up an turn off an alarm when they need to be coordinating with first responders.
Yea, probably better ways. Look up Annunciator panels.

Back in the 80's I did a "safety system" The operation is somewhat "backwards" from what you want.
it was built with 3PDT relays. One pole did the alarm loop, one pole did the light loop and one did the latch. A momentary closure would energize the appropriate relay and latch it. The indicator would light and the "alarm loop" would be broken.

ON/OFF momentary buttons were used to SET/RESET the panel and a key switch was used to "disable the panel". i.e. Permanent shutdown.

Standard industrial rectangular indicators with labelable lenses were used.

"monitored" contacts would be the way to go. It's the way FAP (Fire Alarm Panel) systems work. The Normally Open contact has a resistor across it, so if the line is cut the panel knows about it. i.e. "trouble.

For one or two points, I used a second LED and an SPDT contact. The LED showed that that point was connected. If the FAP LED was OFF, (i.e. The FAP was still commanding the panel to shut down) and the panel could not be reset. If any one of (two of the three wires) were cut, the panel would know about it.

One or 2x/year it was desirable (FAP testing) to prevent the FAP from shutting down the panel. A connector could be pulled "inside" the panel preventing the shutdown and extinguishing the LED.

Thread Starter


Joined Mar 17, 2013
Thanks for the suggestions, KISS, very helpful ... I think I have an option now to work with unless I hit a brick wall. I will be back if I need more
help but hopefully I can handle it for right now. Thanks again and have a good week.
Best regards.

Thread Starter


Joined Mar 17, 2013
Well, I'm back with more questions.
Starting from scratch, here is the scenario of what I would need to please the client. There are 3 locations in a public building that want a "panic" button to signal the sheriff's dispatcher
that officers are needed to intervene in a developing situation.

What is desired is that the momentary push of a button will yield a contact closure there and a wire pair runs from the switch all the way to the dispatch room on ground floor.
Here we want a display with 3 red indicators (one for each of the 3 locations monitored) and a buzzer/sounder to draw attention to the dispatcher. He would see from the
display which location requested the help and proceed to dispatch officers to the location. (also would like a suggestion on how to label the red indicators so it is clear yet
takes up minimum space.... sheriff is adamant about keeping this to least amount of "crap" and wires necessary... tough to please).

Rather than the dispatchers have to worry about and take time to reset or cancel the light and noise after handling the emergency, I think they would accept another option.
With the proper circuitry, the light and sound would only last for a pre-set time.... great if it could be field adjustable.... and then shut off. It should be long enough to notice
if they were not exactly at the desk but not so long to be irritating and interfering with ongoing processes.

It would be ideal to have the sound/buzzer be on for a certain number of seconds, then go off but with the red light (blinking) remain for a minute or two so an officer that
stepped away for a minute would still be able to see the light once the noise had caught his attention.

With the sheriff's request for minimum clutter & wiring in his area, to what extent could I locate these items near the origin of the signal and yet get required commands to
each light/buzzer. This setup would then be done the same for each of the 3 locations.

I don't know anything about it but a PLC (programmable logic controller) device was suggested but sounds to be a bit overkill when it is just a couple of logic and timer steps involved I would think.

Any help will be much appreciated!

Above link is example of what I have come across for the light/buzzer. Have to make a box or panel and insert and label these ... or something better.


Joined Jan 15, 2015
One thread is enough. Starting multiple threads on the same subject will only serve to confuse those who would help you. I just replied to the other thread you started with some suggestions and a basic drawing.

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