Posted this on old thread as well but thought it would be noticeable as a new thread so here it is:

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!

http://www.automationdirect.com/adc...ors/22mm_Plastic/Audible_Buzzers/ECX2071-127R

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.
izon, 37 minutes ago Edit Delete Report

 

Budget? Voltage you want this to run on? Personally I would go with a low voltage DC system. How long will these wire runs be? What you want to do isn't difficult but you need to define a few more things. I haven't a clue what your location is but here in the US for example you can't just start dragging bell wire through a building carrying 120 VAC. Plenum cable? Riser cable? You do a professional job it meets for example NFPA regulations and conforms to specifications. The drawing BOM (Bill of Materials) calls out all the parts. When you say Public Building all sorts of interesting things happen.

What you are looking to do from a design point is simple, just a matter of drawing it up but things like budget and NFPA rules come into play.

Ron

 

You want something along these lines. I did not identify the relays or pin outs, I would likely use Omron MK3P5-S 3P3T 24 VDC Coil relays. That leaves plenty of extra contacts for any future additions or plans. The circuit would be repeated 3X or as many times as you want. It's a very basic latching type circuit.



Ron

 

a wire pair runs from the switch all the way to the dispatch room on ground floor.

Is the wire rated for mains use, or is it just low-voltage bell wire or CAT5 cable or similar?
What is the present system of indicating that a panic switch has been operated?
What official Regulations and Insurer's Approvals would need to be complied with/obtained for the system?

 

Sorry didn't mention I'm located in the US. It is currently out of commission. Some construction and communications contractors chose to cut off and/ or disconnect things without bothering to find out what they were for or if still in use. The wiring you ask about is "low voltage" and I know electrical code.

 

Sorry didn't mention I'm located in the US. It is currently out of commission. Some construction and communications contractors chose to cut off and/ or disconnect things without bothering to find out what they were for or if still in use. The wiring you ask about is "low voltage" and I know electrical code.

Then I would consider something like I posted which is sort of Industrial Brute or I liked the suggestion by someone it the other thread that suggested a uC based system. Since you know the code and NEC angles it is pretty much your call. The circuit I posted is a rough idea and for example I did not include timeouts. Last system I did similar to this I used some red strobe lights I bought from McMaster Carr Supply and it was a 24 VDC system.

Ron

 

Here is another although very similar approach with a microcontroller (uC). The schematic below is a rough draft - we'll need to know more.

The OP can use any micrcontroller but I'd suggest the PICAXE if new to programming. The buzzer is a piezo - the uC can either have the piezo buzz or even make a short melody. Volume is controlled either by changing the voltage to the piezo or adding a mechanical baffle of sorts.

The potentiometer can be used to adjust timing, either of the piezo, the flashing of the LED's or both.

Using a uC allows the OP to program how fast the LED's flash, how long, the piezo sound, etc. A switch with multiple positions could be added to change these values to something preset. For instance, position 1 would be a default while position 2 would cause the piezo to sound longer in the event the dispatcher needs to step away.

I've chosen normally closed switches only because in my limited exposure to alarm systems, I learned having NC contacts better ensures the system is working. Using NO contacts, you have no feedback - if the wires were to get cut again, you'll never know. With NC contacts, the alarm will sound. Of course, if you're going to turn off all sounds and lights after a preset time, this may be irrelevant. You could leave the LED's on all the time to indicate everything is working properly OR add another LED to indicate power is on but that also flashes if any of the external buttons appears "open" for long length of time.

You may opt to add a reset switch to the circuit so that when a button is pressed in the building, the buzzer goes off for a short time and the LED's flash continuously until the dispatcher presses the reset switch. In this way if someone steps out for awhile, they'll still know a button was pressed since they left. If your customer doesn't want a lot of "crap" then this probably ain't worth adding.

Is the dispatcher in the same building as the three panic switches?

What is the longest distance (accounting for turns and going up and down walls) between the dispatcher and the buttons? As others have suggested, you'll probably want to use something like 24VDC or so to better handle voltage drop, then we can add an optoisolator or similar between the buttons and the circuit.

You could eliminate a lot of wiring by using wireless modules, but then reliability becomes an issue.

If you need to keep it small and simple, this could fit into a small 1" x 1" x 2" box or so (probably a little bigger to be safe) with two to four power wires and six wires to the buttons (maybe even four).

 

I like that. The only thing I would add is another series push button switch with each of the existing at the panel itself making for a local push to test and maybe a local reset. I also agree as to the use of a PICAXE making for pretty easy programming. Any additional whistles and bells including delays or timing could just be programmed.

Ron

 

Thanks much... sorry for not responding earlier but did not get the expected email notification of new posts as I had been getting before.
I have just quickly scanned your posts and haven't had time to completely think on them.
However I have a several questions to start with;

1. I have been told to use 24vdc as supply since any line disturbance won't be so likely to false trigger anything....your thoughts? 12vdc might be easier for me.
What would determine the voltage to use where you indicate "VDC" on the far left? Guess a voltage divider from that would supply the 5VDC for the chip?
So the VCC for the piezo would be whatever the piezo requires but could it be also derived from the main supply? ooops, just saw your note on 24vdc...OK

2. I'm just not familiar with nor have I ever done any programming of a uC so that area is new to me. ( I'm just and old codger .... LOL )

3. I very much like your paragraph about the ability of adjusting the LED flash rate and the length of piezo sound and sound options... btw... do you know of
some audio files on the web that would give examples of some of the choices of the type of sound possible.?

4. You asked it the dispatcher is in same building as panic switches... YES, switches are on third floor center and dispatcher on ground floor far end
That wiring is in place from the previous system.... don't recall what I used exactly but is low voltage type and it was working before and I think I was
using 12vdc for power.

5. Here (see link to ebay) is an idea I've come across for the LEDs so with something like that (available in 24vdc) could this be used as the indicators?
http://www.ebay.com/itm/141440302915?_trksid=p2055119.m1438.l2648&ssPageName=STRK:MEBIDX:IT Note: this also has a sounder/piezo

6. I very much like the idea of using NC buttons for reasons given .... however, I may want to use an auto-dialer to the sheriff as a backup or confirmation
of the light/buzzer indicators. That would require a NO contact set in the buttons .... so is there any way I can accomplish this with both systems as being discussed?

Thanks for now. I may know more of what I need or will be able to do after the interested parties meet sometime today to work out what they want so will be able to
proceed on something after that.

 

The only reason I generally prefer 24 to 12 VDC is less I*R loss for longer wire runs. Really, if 12 volts will suit your needs and work for you then 12 volts is fine. As to a uC? I would power it off a LM7805 or similar. A voltage divider won't really work to power the uC. Just about any indicators or annunciations can be worked into the scheme, pretty much your choice.

As to #6 incorporating an auto dialer should not be a problem as the uC can be programmed to handle that. While I am not really a uC programmer type I see no problem including an autodialer function. Just means more hardware. To acomplish this when an alarm condition exist (is triggered) a specified pin on a uC goes for example High and initiates a phone call. I have seen this done with an Arduino uC.

Once the interested parties meet they can define a work scope and then you can put together a list. Almost like a Must Have and Nice To Have list.

Ron

 

Thanks for the reply Ron. In regard to the auto dialer, I had planned on the "panic" button contacts closing to initiate the dialer. I plan on using an auto dialer in another building with
alarm buttons so wanted to do the same here. I'd prefer to bypass this uC circuitry and have the dialer proceed just from the button closure. That way it eliminates any failure or
glitch with that extra hardware and becomes a more reliable alternative. If I used the uC portion which controls the light and buzzer, any failure of it would likely also result in
a failure to initiate the backup dialer system.
Soooo any way to preserve the NO contacts for the dialer to work and yet have the benefit of the NC contacts for the uC circuitry?
I should check the dialer and see if it will accommodate NO contacts but doubt it.
Thanks for now.

 

I agree with Ron regarding the voltage regulator and defer to him about 24V vs 12V. I don't have experience running low voltage long distances, but I'm glad he explained why 24V might be better.

So, you want the ability to change blink rate and control the buzzer with a uC, but not to activate the auto-dialer which uses N.O. contacts? It's possible, but if you plan to stick with N.C. button contacts, you'd be trading worrying about the uC failing for something else. You'd need to invert the signal from the N.C. buttons which adds parts and complexity. Perhaps someone else can think of a simpler solution. You wouldn't be having the uC do much, so I don't think you'd need to worry too much about uC failure.

Wait, I have an idea. You could use buttons that have both N.C. and N.O. contacts. Wire the N.O. contacts in parallel with the auto-dialer and the N.C. contacts as shown above to the uC. If the uC fails, the buttons will still trigger the auto-dialer.

Does the auto-dialer need a voltage applied across the N.O. contacts or is it simply looking for a short?

To use 12V or 24V buttons with the uC, I think adding an optoisolator will be the simplest solution.

Sorry, VDC on the far left should be 5VDC. I'll need to redesign for 12/24V operation with optoisolators.

 

Just read the spec sheet on the dialer...... good news, it can be activated in a NC contact mode. So That should make it possible
to just parallel the lines to the uC and to the dialer, correct? See specs:

Power source: 9-18VDC Activation: 1) N.C. Activation: dialer activates when an "open" is detected
2) N.O. Activation: dialer activates when a "close" is detected
3) Voltage Activation: N.C. (applied voltage: Min. +5VDC, Max. +28VDC) N.O. (loss of continuous voltage: Min. 0VDC, Max. 0.25VDC)

Here is the dialer unit:
http://www.surveillance-video.com/security-ad2000.html/?gclid=CMPHmNaJuMQCFYNAaQoddLkAMw

Will check in later when I get a chance to and if I have been given a go-ahead on the job.
Thanks again, guys.
Harlan

 

Activation:
1) N.C. Activation: dialer activates when an "open" is detected
2) N.O. Activation: dialer activates when a "close" is detected
3) Voltage Activation:
N.C. (applied voltage: Min. +5VDC, Max. +28VDC)
N.O. (loss of continuous voltage: Min. 0VDC, Max. 0.25VDC)

You can even activate from a pin on a uC going High or Low using #3 Voltage Activation.

Ron

 

Yes... gives us a variety of options..good deal. Will have to see if things move forward, do some more detailed planning.

BTW... not the place for this question but for some odd reason, I'm not getting the email notifications that I had at the
beginning of this thread. I've checked everything I can find to be following the forum, checking the boxes for wanting
email notifications at new posting on the thread and whatever else I could figure out but still .... no emails.

And for some reason, I can no longer see elec_mech's diagram... just blank on the page. I can still see yours, Ron,
just fine but not the other one.
Thanks
Harlan

 

Before I get too far into this uC method, I have never worked with one and so know nothing about
programming or how it is done. Is this going to be possible for me to set up the way it needs to
operate without any prior experience?
Thanks....

 

If you're not seeing my diagram, off the bat it sounds like you're not logged in, although I'm 'seeing' you're online now which means you are logged in - nevermind. Might want to try contacting a moderator to look at your account. Or you can start a separate thread - that will probably get you an answer the quickest.

Before I get too far into this uC method, I have never worked with one and so know nothing about
programming or how it is done. Is this going to be possible for me to set up the way it needs to
operate without any prior experience?

Sorry, I meant to say earlier that I'll write the code and you can modify it to suit your needs. The PICAXE uses BASIC language and I'll comment everything, so modifying should be easy. Having the uC handle the control to the auto-dialer would simplify things. You can always try it out and modify it during the testing stage if you don't feel you're get the reliability you need.

 

Well now I get emails to every post on the "Projects" forum except nothing from my own thread ??? Also wondering on the list of projects showing all the threads, every one except mine is titled in bold type???. Still no diagram of your circuit, elec_mech but Ron's shows up all the time just fine.
Well I have some more thinking to do as I wait for word about if I get the go-ahead on this matter. Thank you.

 

You mentioned PLC being a little overkill, so what about a Smart Relay? This is a cheaper form of PLC and has timers, counters, rela time clock if needed, as well as the I/O required.
These are cheap and plentiful, Most are practically identical to each other, some just relabeled, Omron, Idec, Siemens to name a few.
Max.

 

Thanks for your suggestion, Max..., I had not been aware of Smart Relays at all so have spent a lot of time on the net researching and reading and pricing them. Seems the lowest cost type to do the job along with programming cable, etc. would run in neighborhood of $150.

The PICAXE in a simpler version appears to be less than $10 and other small parts should be reasonable to complete the rough draft plan from elec_mech.

To review, it would need three (buttons) inputs and two output types.

1. output to sounder/piezo device preferably it could have some sound type choices and be set to be intermittent to be a bit less annoying.

2. each of 3 LEDs makes it 3 outputs to individual lights to indicate which room is calling for help.
(each output, sound and light, should be able to come on right away and then shut off at a pre-set amount of time)
Would again appreciate telling me where the best source would be and what version of PICAXE chip I would need.

I haven't headr yet from the folks making the decisions on this so could be another week or two to find out exactly what will be needed.

Thanks again, everyone, for your time and assistance !