How to use a mat pressure sensor to activate a motor??

Discussion in 'The Projects Forum' started by dolos23, Nov 14, 2010.

  1. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    I need someone to help me. I have a mat pressure sensor that comes with an alarm monitor. I want to use the mat pressure sensor to activate a motor when some one steps on it and I want the alarm to sound off too. After the person gets off the mat I want the motor to shut off and I want the alarm to shut off. I'm running it off of a small 12 volt battery. I hooked them up to a relay but I can't get the motor to turn on when I step on the mat. The mat has 4 wires. SOMEONE PLEASE HELP ME WITH THIS PROJECT. IT WILL BE GREATLY APPRECIATED. Thanks-
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Do you have any info or a link for data on the mat?

    Ken
     
  3. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    No there is no technical information on it. I got it from ebay and it was shipped from china. It came with a alarm monitor that goes off when you step on the mat. It uses 6 volts, 3 triple A batteries. I removed the batteries and solder the battery wires to a small 12 volt battery because I know the relay I have operates only with 12 volts. Here is a picture of the alarm monitor bread board.
     
  4. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    More pictures.
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Can you use a tripod to take the photos?

    The mat may have logic circuits in it, so running 12V could destroy the circuit that detects pressure.

    A better way would be to power it as directed, and "tap" the alarm wire to a transistor which would then switch the relay you intend to use.
     
  6. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    Ok here are some better pictures. The relay will is a 12v relay and the alarm monitor runs off of 6 volts. How is the transistor going to turn on the relay?? Please let me know the best way to get it to work precisely. And there is a reset and test button on the alarm monitor that I want to stop the alarm and motor when it is pressed.

    Thanks for your help.
     
  7. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    More pics.
     
  8. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    That is a PIC controller board, did it come with the mat?

    Does the mat still make the alarm go off without the circuit board?

    If the board came with the mat, then you should also feel a click if you put your finger on the relay and step on the mat. If that works, hooking up the motor is a matter of finding the COM and NO connections to the relay, and putting that switch in the moor's power line.

    This is assuming that the motor draws less than an amp or so (what is written on the top of the relay, exactly, need focused close photo of yellow box)
     
  9. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    Hi.

    No the alarm is part of the controller board. It is connected to the controller board. I added a picture of the alarm, it is the round black thing. Yes the relay in the controller board does click when I step on the mat. Here is what is written on the yellow relay in the control board:
    HRS1H-S-DC3V N
    1A 120VAC
    1A 24VDC 10A 1K

    I hooked up the motor to the 6 volt that the monitor alarm comes with and it works but it does not work with the same force like it does with 12 volts.

    From what I gathered there is 3.5 constant volts on 2 contacts of that yellow relay. There is 6 contacts and the rest are at 0 and .4 volts when the alarm is activated.

    Please let me know what you think I should do next. I really appreciate your help. Thanks-
     
  10. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    So you have on the relay:
    Coil pin: (driven by board)
    Coil pin: (driven by board)
    Pole 1 Common
    Pole 1 Normally Closed (NC)
    Pole 1 Normally Open (NO) <this closes when relay is energized>

    The coil pins are the ones showing the voltage when relay is energized.

    The normally closed will show zero ohms between the two points when the relay is not energized.
    The normally open will show zero ohms when the relay is energized (when soembody is stepping on the mat).

    What you want to connect to is that normally open switch, and use it just like a switch. No power is provided by the switch.

    Once you have absolutely identified the normally open switch contacts, there may be a diagram on the relay, or more likely, headers out on the PC Board with "NO, NC, COM" or similar labels. Then you can hook up your motor to the battery as normal, except, cut the positive lead, and have it go to the COM relay pole, and the positive wire from your battery going to the NO relay pole. The negative wire will go straight to the motor.


    If any of this is unclear or doesn't make sense, ask! Trying to power a motor directly from that board, or attempting to use 12V to power the board will likely destroy it in a short time. The relay is provided on the board for exactly what you are trying to do.
     
  11. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,809
    834
    What is the black rectangular object to the right of the relay in your picture?
    [​IMG]

    Is it possible that this is some kind of jack, for an external connection? :confused: If so, this may be where you can connect to the relay's internal switch to control your motor; on similar equipment, I have seen such a jack used to control external devices. Find a compatible connector and test the resistances between points with a multimeter as suggested by thatoneguy.
     
    • pmat.jpg
      pmat.jpg
      File size:
      105.9 KB
      Views:
      53
  12. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Because of what looks like a coil spring near the upper end of the black rectangle, I'm guessing it's a push-on/push-off switch.

    Ken
     
  13. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    I thought it was a spring as well, but it may be threads for a jack similar to an XLR connector, I guess a lot is possible.

    I can't see why they would put a relay on board without having leads out to use it.
     
  14. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    I tested the poles on the relay and I also tested the poles on the auxiliary switch next to the relay and they have continuity. I drew up a diagram of the relay and auxiliary switch. I did exactly like you said and located the N.O pole and connected it to the positive side of an outside 12volt battery and connected the COM to the positive side of the motor. I connected the ground wire from the motor to the negative side of the outside battery.

    It is now working but I don't know if the 12v that is connected to the N.O pole on the auxiliary switch control board will do damage to it. Please let me know what you think. Thanks as usual. And later on if I wish to add some other things to it like a timer or something I hope you can help as well.
     
  15. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    relay(yellow) and auxiliary switch(black)
     
  16. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    The Aux switch next to the relay, does it have something like a jack with pins to connect to it?
     
  17. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    Yeah they made it like that so you can buy the connector for the auxiliary switch separately. I connected to the auxiliary switch to the solder underneath it.

    It is now working but I have a problem because the motor will run continuously until I press the reset/test button on the alarm monitor. I wish for the motor to run for like 20 seconds and then shut off but I want the alarm monitor to stay on until I reset it through the reset/test button. Do you know how I can do that and what part do I need?? Thanks-
     
  18. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    What size motor?

    This can get a bit complicated, but solved with a 555 timer to run another relay for 20 seconds, using a capacitor inline to change continual output voltage into only a short pulse at the beginning.

    See Bill Mardsen's blog on 555 timers.

    Why didn't you mention the auxillary output option in the original post??!?
     
  19. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    A user name Kmoffet told me about that auxiliary switch. I didn't realize they shared the same relay. I can't find that 555 timer blog. Where can I buy one so I can start preparing for it. Thanks-
     
  20. dolos23

    Thread Starter New Member

    Nov 14, 2010
    11
    0
    Whats the step by step I have to follow to place the 555 timer in series with the motor so that the motor only turns on for 20 seconds?? Please let me know. Thanks-
     
Loading...