wiring Relays, in an RFID door access system

Discussion in 'The Projects Forum' started by johntee, Sep 6, 2009.

  1. johntee

    johntee Thread Starter Member

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    Hi Folks. I’m hoping someone can provide me some direction in my (stalled) project.
    I think I’ve bought all the parts I need, but I’ve managed to completely confuse myself when it comes to a couple of the wires…

    ------------
    Access Control Unit: I have an RFID Access control unit (where you swipe an Radio-Frequency ID tag near the reader to gain access into the building). Once it verifies that it's a valid tag, I want to trigger 2 things -- (1) buzz the electric door strike for a few seconds to unlock the door, and (2) turn on the lights in the room for a period of about 10 minutes.

    It's an off-brand access control unit (but it had most of the features I was looking for at a good price), and it seems to be made by KAWA, model #MG236C. The unit and its built-in Lock Relay output are 12VDC. It’s already programmed to buzz the strike for approx 5 seconds.

    The manufacturer told me to “connect the 12V +ve and Ground from power supply to the +12V and GND terminal respectively. Then if you have NO type strike, connect to the NO and DGND terminal.”

    ------------
    Door Strike:
    The door strike is 16-24VAC. I have a doorbell transformer that can put out that voltage.

    ------------
    Relay to feed Door Strike:
    I bought from factorymation.com this relay:
    782XBXM4L-12D Magnecraft Electromechanical Relay, "Ice-Cube" Style, 16A DPDT, 12VDC Coil Specs
    And the socket for it:
    70-782D-1 Magnecraft Relay Socket, 8-pin Cube Style, 2 Pole, 16A, 300V, IP 20 (Finger-safe) Specs

    FactoryMation told me: “The 782XBXM4L-12D relay requires a 12VDC signal between terminals 13 & 14 (referred to as the coil) to energize.
    When energized the normally open set of contacts between terminals 9 & 5 will close. You will use this open set of contacts to switch the voltage required by your load.”

    ------------
    Time-Delay Relay to feed regular 120VAC lighting circuit:
    I bought: 822TD10H-UNI Magnecraft 10 Function Programmable Time Delay Relay, 15A DPDT, Universal Coil Voltage 12 - 240 VAC/VDC Specs

    FactoryMation told me: “You will need to connect a separate power supply to the 822TD10H-UNI for control power. This power supply voltage( 12~240V AC/DC) needs to be connected to terminals A1 & A2.
    When energized the normally open set of contacts between terminals 15 & 18 will close. You will use this open set of contacts to switch the voltage required by your load.
    The timing signal needs to be a dry contact (no external voltage) between terminals S & A1.”

    After a follow-up question by me, he said: “In order for the timer to work, the voltage that is applied to terminal A1 needs to be connected to terminal S, typically through some type of external switch.”

    Then after a further question by me he said: “Yes, A1 & A2 are used to power the timer.
    You CANNOT use an external voltage to control the timer. The S input must be connected to the A1 input (through a switch or a relay contact) to start the timing sequence.”

    This time-delay is where things really got confusing for me… I figured that the time-delay relay needed a separate power source even after the 5-second signal had stopped (that makes sense, so it can keep counting down). But he’s saying now that it has to be the SAME power as the Signal? That part I just don’t understand. (In his first answer, he even said “you will need to connect a separate power supply…for control power.”)

    Here’s my drawing of the various components, with my attempt at the wiring.
    If anyone could give me the correct wires to connect, I would be so appreciative!!

    Does polarity matter on 13 and 14? Did I get the polarity right on all the other wires?

    Do the 9&5 pair and 15&18 pair care which terminal of the pair is the input and which is the output? Or is there a protocol for that?

    (I decided to buy Double-Pole relays so that I could eventually expand the controlled functions, once I started to realize how cool relays are! But right now I’m just looking to control one function for each of the relays -- feed the door strike from one, and turn the lights on for 10 minutes with the time-delay relay.)

    Thanks in advance for helping me get this project back down off the shelf!
    John
    [​IMG]
  2. williamj

    williamj Active Member

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    johntee

    The way your sketch shows the S and A1 connections, tells me that they are recieving signal voltage from the access control unit. If S and A1 are to be "dry contact (no external voltage) then this is incorrect.

    "A1 & A2 are used to power the timer. You CANNOT use an external voltage to control the timer. The S input must be connected to the A1 input (through a switch or a relay contact) to start the timing sequence.”

    Try connecting S and A1 to 12 and 8 on the 782XBXM4L-12D Magnecraft Electromechanical Relay.

    Not only do I hope this helps I hope it works.

    williamj
  3. johntee

    johntee Thread Starter Member

    Joined:
    Jul 20, 2009
    Messages:
    15
    Wow, you guys are good! (And fast!)

    In your diagram, Alberto, I had a few questions --

    On the Access Control Unit:
    So I shouldn't use the DGND terminal as the manufacturer said? Just bypass the Access Control Unit entirely for the Relay's neutral?

    Time-Delay Relay:
    This is where I'm still confused. Isn't A1 positive, and S is also positive in your diagram? If I'm interpreting the symbol on the relay's wiring diagram right, it seems to show A1 and S as potentially connecting...
    [​IMG]
    That's the part I really don't understand -- how the constant power and the signal power interact in the relay, and the warnings about no external voltage and the need for a "dry contact" (I just don't know what that actually means.)

    Below is your diagram with my markings, to help it be more legible to me.
    Thanks!
    John
    [​IMG]
  4. johntee

    johntee Thread Starter Member

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    Hi Alberto.
    Was I interpreting the symbol on the Time-Delay relay's wiring diagram right? Are A1 and S potentially connecting to each other?
    [​IMG]

    Here's some info on the Access Control Unit:
    Thank you!
    John
  5. johntee

    johntee Thread Starter Member

    Joined:
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    Messages:
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    OK, so A1 and S never connect to one another, even when the Signal comes from the Access Control Unit... So it makes sense to you, with A1 and S both being positive? (I don't want to blow out the Time-Delay Relay; it was pretty expensive.)

    I like that you added in those protective features (diode and fuse). A couple questions about them --
    What parts of the system is the Diode actually protecting? Is the Access Control unit protected if the diode is located on just the one leg of the wire that feeds #13? (i.e., couldn't a spike from the 782XBX relay travel right back to the N.O. terminal?)

    What kind/size of diode is it? (I couldn't find any Google results on "1N4UU4".)
    What kind/size would the fuse be? (Note, it's only a 120VAC circuit, not 240V as you originally had in the diagram, and it will be run in 12/2 wire (20-Amp circuit breaker).)

    What's the appropriate gauge of wire to use for all these 12V runs?

    Thank you!!
    John
  6. williamj

    williamj Active Member

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    Alberto,

    Just or my edification, wouldn't putting A1 to S through the second set of contacts(8,12), in the 782XBX relay, eliminate the need for an additional componet (the diode)?

    williamj
  7. johntee

    johntee Thread Starter Member

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    Jul 20, 2009
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    Hi Alberto... I began wiring all the various components last night, and I started with just the 12VDC transformer connected to the Access Control Unit.
    I had first tested with a multimeter the 2 black cords that come out of the 12VDC transformer (since the wires weren't marked as to positive or negative); when I got a Positive voltage reading (rather than a Negative one of the same amount), I marked the cord connected to the Red probe as Negative, and the other as Positive.

    These wires got connected to the GND (Red wire) and +12V (Black wire) terminals of the Access Control Unit. When I plugged in the transformer, the Unit made a soft clicking sound after a second (almost like it was activating itself in some way), but after about 3-4-5 seconds, it made a sizzle and a puff of white smoke came out...

    Did I get a bad unit, or did I reverse the wires? The red probe is on the multimeter's VQ port and the black probe is on the COM port, and now I'm starting to second-guess myself... Did I just fry the control unit?

    Thank you!
    John
  8. johntee

    johntee Thread Starter Member

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    Hi Alberto. Could you check your private messages for a question from me?
    Thanks!
    John
  9. johntee

    johntee Thread Starter Member

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    Jul 20, 2009
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    Hi guys, and especially Alberto... I'm finally getting to wire up this circuit, and using the multimeter I found that the N.O. terminal on the Access Control Unit is actually a Negative. (In Alberto's schematic, it was assumed as Positive.) I've altered the schematic, and utilized the 2nd set of contacts in the 782XBX relay to feed a burst of Positive over to the S terminal on the Timer Relay (since the older schematic would actually have been sending Negative to terminal S).

    Could you take a look at it and see if I've covered everything? Also, does the clamping Diode need to be reversed in its directionality now? (Since 13 and 14 switched polarities in the revised diagram.)
    It seems like the Diode is not in a position to protect the Timer Relay now. Do I need to add another Diode down there? If so, where and in what direction should it allow flow?

    Thanks all, as always!!
    John

    [​IMG]
  10. tattooekaos

    tattooekaos New Member

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    hello John

    I am a total newbie when it comes to electronics and building circuits and things, but I am going to be starting a similar project very soon. I live in an apartment building, so I am unable to modify the door jamb to allow for the electronic striker, so I am working on building a device the will kick on a linear actuator that will drive gears to turn the deadbolt from the inside. I also want to be able to have it turn on my main living room light when it unlocks the door.

    I am at a loss so far at understanding a lot of the stuff involving relays and switching, building the box and a the actuator and gears is much more my style, but I am a big tech geek and always love to learn things. I believe I have purchased the same kawa rfid controller keypad that you have. I am hoping that you can give me some advice and some help, bc I am often carrying a lot of stuff when I come home and being able to just wave the fob and push the door open with my light already on would be amazing!

    I hope your project has gone well, and any advice or help you can give would be greatly appreciated!
  11. johntee

    johntee Thread Starter Member

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    Hi Tattoo... I had a few thoughts -- I'm wondering if the setup you're contemplating (gears to turn the physical deadbolt latch when activated by the RFID controller) is going to be a bit of a clumsy interface -- I'm expecting you'd have to mount a box of some sort over the deadbolt, run the wires across the door and out from the hinge side, etc. Probably something like:
    http://www.buyasafe.com/Keyless-Door-Locks-p/kfd.htm
    but with wires coming off it. I'd also be concerned that you not cover up the manual thumb latch on the inside, in case you ever have to exit in an emergency or power outage, etc.

    Having said that, perhaps this article would help you for ideas: http://www.instructables.com/id/Control-a-Schlage-electronic-deadbolt-with-an-ardu/ if you're able to swap out the existing deadbolt.

    The RFID controller completes a 12VDC circuit for however many seconds you set it for, when it gets presented with the right passcard/key fob. Kawa suggests that you don't connect your subordinate appliances directly to the RFID, since the current passing through it can shorten the life of the controller. Hence, the need for the relay... To keep the room lights on for longer than the 5-second pulse the RFID puts out, I had to add a timer relay, which was pretty expensive ($50), although I had needed an adjustable one for my project. Not sure if you can get cheaper, more basic ones if you could accept a pre-set amount of time.

    (I'd seen some posts -- not sure if they were on here or another site -- where people were using some basic sort of resistors to "make" a rough timer -- i.e. the resistor would take some length of time to make/break a connection. Not sure if that would work for you, but it was a cheaper route than the programmable timer, although not as precise or customizable.)

    For my house, I got this voice-activated "clapper" called IntelaVoice --
    http://www.vossystems.com/intelavoicedim.htm
    Instead of clapping your hands to turn it on/off (tough to do if you're loaded up with groceries), you just say "Computer!"; it beeps to let you know it heard you, then you can say "High", or "Medium" or "Low" or "Off" and it turns the plugged-in lamp on at that level. Pretty convenient, and if it's your main living room lamp, you can adjust the lighting level while you're watching TV without getting up. I think it was only about $20.

    I'm attaching the final schematic (missing spike protection on the AC transformer and fluorescent lights, which may not affect your setup). Note the diode; that's there to protect the electronics from the voltage spike that occurs when the RFID controller stops power to the coil in the relay. You just make a slight break in the 2 wires' insulation and solder in the diode between them. Make sure you point the diode in the proper direction! Ask me if any questions on that. It's a Radio Shack item, really cheap (maybe $1 for 2 of them).

    A good idea to add a supplemental fuse to the system (AC portion), and vital if you're using smaller wire for the AC portion than your main circuit breaker is rated for. If it's just some lights, a 1-, 2-, 3-, or 5-Amp fuse is plenty. (Your main breaker is probably 15A or 20A, so unless you use 14-gauge or 12-gauge wire for your AC connections (respectively) you'll have a fire hazard on your hands if you don't have a smaller-amp fuse installed inline.

    And definitely use a multimeter to test the terminal pairs before you make any connections; the Kawa documentation is not precise (often the English is so awful that you don't know what they're even trying to say), and sometimes I think it's just plain wrong. Make sure that you're properly dealing with Negative and Positive, not reversed, or you'll burn it out. (Red is usually Positive in DC, sort of the reverse of what you might expect from AC experience.)

    The relays I got from FactoryMation:
    --- 782XBXM4L-12D Magnecraft Electromechanical Relay, "Ice-Cube" Style, 16A DPDT, 12VDC Coil Specs
    --- And the socket for it: 70-782D-1 Magnecraft Relay Socket, 8-pin Cube Style, 2 Pole, 16A, 300V, IP 20 (Finger-safe) Specs
    --- Time-Delay Relay to feed 120VAC lighting circuit: 822TD10H-UNI Magnecraft 10 Function Programmable Time Delay Relay, 15A DPDT, Universal Coil Voltage 12 - 240 VAC/VDC Specs
    The Diode (1N4004) was from RadioShack.

    Good luck! Let me know how it goes, or if any Q's...
    John

    [​IMG]
  12. tattooekaos

    tattooekaos New Member

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    John

    I like the voice controlled one, that fact that you have to say computer reminds me of star trek. I understand that the way I would like to do it is not the tidiest way things could be done, and I am also doing my best to avoid things like an arduino b/c programming is not my thing. I have looked into the remote control deadbolts, and know I could easily mod that to do rfid also, but the price is a deterrent for me. this is basically like a hobby project I am working on to get back into electronics and building stuff.

    I have no issue with a project box mounted non-permanently to my door, and the rfid controller wires come through the peephole. having the wires cross across the door frame is also not a problem, I have lots of wire loom as well as paintable wire channels for the wall. the whole goal of it overall is to be non-permanent , non-damaging to the door, and keep the same deadbolt so maintenance could get in if they had to. I really want to build an all in one little box for the outlet my lamp is on, for it to be controlled by the rfid controllers output, but also to provide the power for the controller itself, and all that stuff can be run through wire looming to the door.

    I also understand that the deadbolt latch wouldn't be able to be turned normally if I didn't use a gear set that has a slip clutch in it that allows it to just slip out and move freely when not being powered. The things like the actuator and the rfid controllers are pretty cheap, I should be able to apply my brain power and that of the many people here to make a device that suites my needs and will probably cost less overall then just the remote lock would have cost me! I also have friends in college and living at home that are really interested in this for fun and simplicity, and if it works out they want me to build one for them.

    I am going to go start reading about the basics of electronics and relays b/c I need to understand these things to be able to make this work right. I am watching one of those remote deadbolts on ebay right now, its has a day left and is only up to $5, so if I can get that cheap then a lot of this will be way easier.
    Thanks for all the input, and I hope this project isn't beyond my ability to accomplish!
  13. johntee

    johntee Thread Starter Member

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    Jul 20, 2009
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