Installing a switch on a PIR alarm detector in garage

[craignigel]

Hi
Recently my garage had to be rebuilt and the switch operated by a key that was fitted outside the garage has been removed. This enabled me to switch off the PIR alarm sensor in the garage as I approached in my car without going into the house and using the alarm panel to disarm the system. I could then park the car and switch back on the sensor as I left the garage before going into the house and switching the alarm off on the panel.

The builder lost the wiring diagram for the relay key switch and has also damaged it. So I thought that I would try to design a simple replacement but using a remote control relay and a project box fitted outside the garage with two LEDs (red & green) to show the status of the PIR sensor.

Please see attached photos of PIR and old key switch with relays.

I would like to know please do I connect the PIR sensor terminals in series with the relay (NO) terminal and common? Then wire in in parallel the red LED across the same relay terminals. Finally, I could connect the green LED across the relay (NC) relay (NC) terminal. I am powering the relay with an independent 12v supply via a mains adapter that I have bought. In fact I have all the components and I am trying to build up a model of my design on a breadboard. I have the relay and LEDs working fine but I am unsure of the connections to the PIR sensor.

Many thanks for your help.

 

[sparkymarka]

Just wire a pair to the pir relay to short out the pir . Simple

 

[craignigel]

Thanks but I want to use 2 LEDs (green and red) to indicate whether the PIR is potentially armed and fix these on a project box on the outside of the garage. So I need to wire in these two LEDs plus resistors each in series to the corresponding NO and NC outputs from one of the relays. So I guess I'm asking is whether this will affect the PIR with any current flowing into it from my independent 12v power source.

Thanks.

 

[sparkymarka]

First thing does the remote relay have an option to latch ? If not you are wasting your time.... One led will need connecting to the set ouput of the panel to indicate if the system is armed or not and the other led needs to go on one of the spare relays , so that when you press the button to latch the relay(short the zone out ) it puts voltage to the led via the relay as a indicator. To say it's ok to enter...

 

[EightyTwo]

I haven't looked at the photos, but a single pole keyswitch could be used to energise a double pole double throw relay. One set of changeover contacts could be used to "swap" the LEDs and the other to shunt the PIR.

For the LEDs, join, say, the anodes together and to the positive supply, the red LED cathode to the NC terminal, the green LED cathode to the NO terminal and the COM terminal to the negative supply.

For the PIR, connect the NO and COM terminals from the second set of relay contacts across the alarm pair in the PIR (or across the zone in the panel/expander, if you're not using resistors).

Use the keyswitch to energise the relay. If the switch will only let you withdraw the key in one position, you'll have to re-arm the PIR before you take the key out. This could be a good way of making sure that you don't forget!

 

[EightyTwo]

... I should have looked at photos! ...

This keyswitch is, essentially, a double pole changeover switch with tamper. The red and yellow wires go to the red and yellow on the Dualtech to shunt it. The blue and black are probably wired to a tamper circuirt somewhere. You could use the changeover terminals on the righthand side of the photo to do the red and green LEDs.

That switch works with five reed switches. The one at the bottom is for the tamper and the magnet is in the back box. The other four are wired as two pairs, one top and one bottom. The lock has a magnet on the lever and, as you turn it, the magnet activates the top reeds or the bottom reeds. Since one top reed and one bottom reed are wired together at one end, this becomes the Common terminal for a rather slow changeover set.

You probably won't need an additional psu. You should be able to use the AUX power from the alarm. Your LEDs should only need about 20mA each and you won't have them both on at the same time! This isn't much more than the Dualtech you have. If you're going to use a relay, use a high sensitivity (low current) one and you shouldn't have a problem with that either. However, if you're goung to use this switch, do make sure that you put a diode across the relay coil to catch the back emf and don't use a 'universal' AC/DC relay as reed switches really don't like inductive or capacitive loads!

We've used this exact setup for cycle sheds, mower sheds and similar outbuildings. We didn't use relays.

 

[jonm01]

Looking at the photo your unit has 4 relays. According to the specifications for this unit ( found on eBay) there are 3 modes, latch, auto latch, and non latch. It looks like latch is the one you want. You can derive a 12v power from the pir supply. It looks like each relay has 3 contacts (ie changeover.) You need relay A to short across ( in parallel) the pir alarm loop connections when it's energized, ie when you press A. It will stay in this state, ( leaving the garage un alarmed) until another button is pressed, at which time, the relay corresponding to the new button energizes, and relay A is released. You can use relay B to control the leds. Connect so that the green led is lit when relay B is de energised and use the changeover contact of relay B to switch over to the red one when relay button B is pressed and the relay is energised. So press A, alarm off, green led on, pressB alarm on, red led on. You need to disable buttons C and D if possible since either of these will result in alarm on, but green led!

 

[craignigel]

Thanks so much guys. You've given me just what I wanted. I will work through your designs and I can understand much of what you suggest. You are right about the relay. I got it on Amazon. I bought the toggle version but its easily changed to momentary (which I don't think I want, latched or a mixture, using the jumper. I've been experimenting on my breadboard using LEDs with latched today, before I read your replies.

The relay came with a link to some general instructions: I've taken out the live links in case I break forum rules.

xxxxxx.http://www.safaridrives.co.uk/manuals/DC12V-4CH.docx

I also found this URL pretty useful:

xxxxxx.http://rfremotecontroller.wordpress.com/tag/4-channel/

I'm very grateful for all your ideas & replies.

nigel