Help hardwiring a wireless PIR

Discussion in 'Alarm & Security Systems' started by Ishaq Mir, Jul 15, 2017.

Share This Page

  1. Ishaq Mir

    Ishaq Mir n3wb

    Joined:
    Jan 15, 2017
    Messages:
    20
    Likes Received:
    2
    Hi everyone

    Long story short, I got a high end optex outdoor PIR at a bargain price but problem is it's the wireless version designed to be fitted to a small transmitter.

    The PIR does have all the terminals as you would find in the same wired version. The big difference however is that the alarm output in the wireless version is controlled by a very low current solid state form c relay with max 10VDC 0.01A rating. Where as the wired version has a real mechanical on/off relay that can work with 12V cables over a long distance.

    I called Optex Technical and they told me that hard wiring the wireless PIR with my 15m long 12V cable may give erratic behavior as the solid state relay in the wireless is not a true on/off switch.


    I was coming up with a work around and thinking of adding an intermediate relay system connected to the PIR alarm output, and then connecting the 12v alarm cable to the other end (N.O) of this mechanical relay.

    Do you think this will work and be reliable? Basically the input side of the intermediate relay would need to be very sensitive to low current (10mA max. Rating of PIR) so that it would detect the trigger from the PIR alarm output and then pass that on clearly as a mechanical ON state to the 12v 15 metre long cable going to the alarm panel.

    Any link to a simple relay that would work? Ideally needs to be a 9-10VDC input relay as the wireless PIR alarm output rating is max 10VDC 0.01A max.

    Thanks
     
  2. CamFan

    CamFan Getting the hang of it

    Joined:
    May 25, 2014
    Messages:
    106
    Likes Received:
    34
    Location:
    California
    In either case, 10mA is not much to work with, most mechanical relay coils will require at least 16mA at 9V (Panasonic TQ2S❍-9V, as an example). So you will likely need a circuit with a transistor/optoisolator or try your luck with a solid state relay (Omron G3VM-62C1). The trick here is limiting the forward current on the LED and making sure the output can drive your alarm input.

    You need to measure the voltage of the relay output. It is either giving you a 0-10V signal, or it requires you to pull it up and it will sink the current to ground. If you get zeros, then you will need to hook up a weak pull up resistor (10K) to the voltage rail (12V).

    If you get the measurements with a volt meter, I can design you a simple circuit. Need to know the voltage when the sensor is normal, and when it is faulted. Also need to know what you plan to hook this up to (Alarm make & model), and what that expects as far as voltage and polarity.
     
  3. tangent

    tangent Known around here

    Joined:
    May 12, 2016
    Messages:
    1,432
    Likes Received:
    583
    If you don't want to design / build something yourself, you could try something like this:
    USA !! 1 PC 12VDC OR 5VDC,1 CHANNEL HIGH OR LOW LEVEL INPUT ,OPTO RELAY BOARD | eBay

    Just watch what voltage is required to trigger it, some operate at 12V, some at 5V. Best bet is probably measure your voltage output and if its 10-12V try one of these. Not sure if the higher voltage version is using a different optoisolator or just dropping the voltage with a diode.
     
    Last edited: Jul 19, 2017
  4. Ishaq Mir

    Ishaq Mir n3wb

    Joined:
    Jan 15, 2017
    Messages:
    20
    Likes Received:
    2
    Camfan and tangent, many thanks for your help.

    I am using the Sealevel DIO 8112 unit with Blue Iris for my PIRs. The 8112 inputs seem to be very sensitive to low current as I've successfully triggered the input with the wireless pir I just got.

    Here are my findings: I first added a 9v (standard alkaline battery with connector) power into the alarm N.O output circuit of the pir and hooked it up to the Sealevel. However, regardless of pir triggering or not the 9v kept leaking through the solid state switch of the PIR and therefore the Sealevel had a constant ON state trigger.

    I then took out the 9v battery and used the 3.3v power OUT connection from the pir itself and added it to the alarm output circuit, this would not trigger the Sealevel at all as the Sealevel input needs minimum 5v. I then kept that connection but added another 3.3v cr123 battery in series to the alarm out circuit to the Sealevel. This increased the voltage to 6.6v. Voila!!! It all started working as it should. When the pir would trigger, the Sealevel input would trigger. Tested it for a good 10 mins. So I guess approx 6.6v is the most the solid state switch in the pir can handle before it just starts leaking the voltage/current through it.

    I'm now ordering a 12v to 5v and 12v to 6v step down unit and will connect it to my 12v psu and run the wireless PIRs and their alarm out from this. Will test both 5 and 6v and see if any particular one is more stable.

    The Sealevel 8112 has input 1 and 2 with a common, then input 3 and 4 with another common.

    The first two inputs have got the 12v running through them, so I guess I'll have to use input 3 and 4 with 6v and not mix any voltages as this may back feed to the wireless PIRs?

    Thanks
     
  5. tangent

    tangent Known around here

    Joined:
    May 12, 2016
    Messages:
    1,432
    Likes Received:
    583
    Running too much voltage through diodes and transistors can damage them.
    Why don't you tell us what model of motion detector you have so we can actually look it up.

    Is this a battery powered motion detector?
     
    Last edited: Jul 21, 2017 at 11:04 PM
  6. tangent

    tangent Known around here

    Joined:
    May 12, 2016
    Messages:
    1,432
    Likes Received:
    583
    Also relevant, what other sensors are connected to the sea level device and what voltage are they operating at?
     
  7. tangent

    tangent Known around here

    Joined:
    May 12, 2016
    Messages:
    1,432
    Likes Received:
    583
    When a spec sheet says 10V MAX for something like the ssr output, that doesn't mean it will operate well close to that voltage. That's the point where damage will occur, but since 9v was leaking I'd say stay under 7.2V. If you use an opto isolated relay module you can use 12V signaling back to your sealevel and run more current without damaging the ssr in the detector.

    I made a schematic showing how to power it from 12V stepped down to 5V and use an opto isolated relay for the signal:
    upload_2017-7-22_0-54-47.png
    You'd need a 5V opto isolated relay module like this: 5V 1 Channel Relay Module With OPTO Isolation High And Low Level Trigger | eBay

    And a 12V to 5V converter/regulator, something like this would work: Amazon.com: Icstation AMS1117-5 DC Voltage Regulator Step Down Power Supply Module 6.5V-12V to 5V 800mA (Pack of 5): Industrial & Scientific EDIT: may not work load may be too small, you could always test with a really big resistor.
    or this one which costs more but should work:7805SRH-C Murata Power Solutions Inc. | Power Supplies - Board Mount | DigiKey
    You don't need that much current for the motion detector and relay, no need for a big converter. You'd have to weatherproof / insulate these a bit (heat shrink tubing might work) but they're small enough to fit inside the motion detector with the relay module (hopefully).

    This setup would also allow you to power the motion detector without batteries.
     

    Attached Files:

    Last edited: Jul 22, 2017 at 3:01 AM
  8. Ishaq Mir

    Ishaq Mir n3wb

    Joined:
    Jan 15, 2017
    Messages:
    20
    Likes Received:
    2
    Hi tangent, amazing knowledge and thanks for that schematic!


    I've ordered the following step downs in 5v and 6v from china, thought I'd order both voltages just in case as they are so cheap anyway:


    Waterproof DC to DC buck Converter 12V to 3/3.3/3.7/5/6/9V Power Module Supply | eBay


    The hard wired PIRs are Takex T15WE - amazing outdoor detectors. Operating voltage 9-28VDC. Alarm output contact rating 24VDC, doesn't give a minimum required for it. I'm using the 12v from my dedicated psu to power it and for alarm contact.

    My psu is a dedicated 12v alarm psu with 10 outputs rated at 1.2A max with electronic cut-off/reset on each output.


    I'm thinking may be I could just change the 12v in my takex 'alarm out' to 5v so that everything going to the Sealevel inputs is at 5v? 5v should be ok over 30 metres of alarm cable right?


    The wireless PIRs I have are the Optex HX40 and HX80. You are right, I am just going to power them with the step down transformer instead of batteries as the batteries cost about £10 per unit.


    All the PIRs in my system will be configured as N.O. So I ordered this solid state D.C. To D.C. Relay, apparently the input current can be as low as 5-50mA for a trigger 3-32VDC. Output can then be 5-60VDC.


    SSR-25DD Single Phase Solid State Module Relay 25A DC 5-60V K9P1 | eBay


    It was only £2.75 from china so I ordered it anyway.


    Would the opto relay you posted above have any advantage over this relay?


    I'm hoping I don't have to use any relay with 5v running through the wireless PIRs and the Sealevel, just means there's less components to eventually fail.


    Thanks
     
  9. tangent

    tangent Known around here

    Joined:
    May 12, 2016
    Messages:
    1,432
    Likes Received:
    583
    RE: the schematic I made, I edited it at one point and fixed a mistake, there are different ways you could choose to hook up normally open/closed outputs. It's also possible that there's an internal pull up resistor, you might want to test it without adding another resistor.

    That buck converter you ordered will probably work, but the motion detector is extremely low power. A 3amp power supply is massively over sized. Voltage regulators and dc/dc converters don't always regulate well where there's practically no load, but a buck converter will probably do ok. Part of what I was thinking with the combination of products I suggested is that they might fit inside the motion detector without an external box.

    It shouldn't really be a problem running different voltages into the sealevel, you just need to connect all of the grounds to the sealevel (even if they share a "c" terminal). I'd leave your Takex detectors running on 12V.

    5V for 30m will be fine voltage drop wise, the thing that could cause problems would be radio interference.

    The trick to using the SSR you bought will be finding and understanding the specs to use it effectively. The opto isolated mechanical relay may be a little easier to setup and use. The output isn't polarity sensitive and can be N.O. or N.C. and it should be possible to trigger it with less current. You can also configure if it's active high or low. The mechanical relay I linked is designed for 5v and may not tolerate 6v. There are millions of motion detectors out there with mechanical relays in them that work just fine, so I wouldn't worry about that.
     
  10. Ishaq Mir

    Ishaq Mir n3wb

    Joined:
    Jan 15, 2017
    Messages:
    20
    Likes Received:
    2
    Hi tangent, thanks for that info. I might just order two of those opto relays and wire it up your way.

    I got an A* in GCSE electronics but that was nearly 20 years ago!! Lol now I'm an optometrist (eyes) therefore my electronics knowledge has gone down the drain, although I'm pretty good at understanding and doing basic 'electrics' around the house.

    I understand most of the schematic there but would you be kind enough to explain what happens when power is turned on, and pir triggers on/off. I'm just a bit confused with resistor and what pull-up is and that high low level input of that opto relay, if you could explain what happens around that area when pir is triggered/untriggered.

    Thanks
     
  11. tangent

    tangent Known around here

    Joined:
    May 12, 2016
    Messages:
    1,432
    Likes Received:
    583
    Current only flows 1 direction through a solid state relay. It's hard to say if you need a pull up resistor, there could be one internal to the motion detector or they could be counting on one in the wireless transmitter. You can see more on pull up or pull down resistors here: Pull-up resistor - Wikipedia
    [​IMG]
    Basically you're dealing with something that's switched to ground and without a pull up it's just floating. When the switch (solid state switch in motion detector) is open the output is pulled high up to the supply voltage by the resistor. When the switch closes the output goes to zero. If the resistor is too small too much current may flow through it in this state. Since your attempt with batteries worked, it's pretty likely there's an internal pull up and you don't need to add one. Also note the power output terminals are just wired directly to the power input terminals.

    Normally closed loops are used more in alarms than normally open because they'll alert you to a broken or cut wire.
     
  12. Ishaq Mir

    Ishaq Mir n3wb

    Joined:
    Jan 15, 2017
    Messages:
    20
    Likes Received:
    2
    Many thanks for that info, I understand pull up now after reading for ages last night and watching videos on YouTube.

    Got another question regarding the 5v power supply to the pir with that buck converter. It's rated as 3A but because it will be feeding from 12v regulated psu with 1.2A max rating/protection, that will make the buck effectively less than 3A right? What would it be exactly?

    I'm thinking I should also use a resistor in the +5v from the buck to the pir power in to limit the current just in case. The manual states 4ma max consumption at 3V. Using ohms law the resistance required for that would be 750 ohm resistor. But then we need to take into account the extra power to the opto relay, about 5ma, so total ma about 10ma?
    Using ohms that equates to about 300Ohm resistor? But do we have to modify for using 5v as the above is based on 3v?

    Advice much appreciated
     
  13. tangent

    tangent Known around here

    Joined:
    May 12, 2016
    Messages:
    1,432
    Likes Received:
    583
    12V*1.2A=14.4 W, 5V * 3 A = 15W
    The 12V supply you have doesn't really effect the output much. Depending on how it handles over current you could see the voltage drop or a fuse blow.

    My point was that a 3amp supply is overkill for loads that could range from 4 micro amps to 500mA. If you want to protect from over current, a fuse would be the right choice not a resistor.
    The bigger issue is that at 0.0012% of the maximum load of the 3A supply you bought it may not have a very well regulated 5V output (but it might work fine).