LED to Relay for bowling alley

Discussion in 'The Projects Forum' started by Pietenpol, Oct 27, 2011.

  1. Pietenpol

    Thread Starter Member

    Dec 27, 2008
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    I had posted awhile back on this but haven't gotten anywhere. Will try to describe as best I can what I am hoping to accomplish. I have 2 devices. An I/R beam reflected that has an alignment LED on it and a 5v relay that closes a NO momentary contact switch. These devices are connected to each other through a processing unit. The proprietary software only uses the I/R to trigger a camera for scoring purposes and nothing else. The processor sends signals to the relay whenever it wants the machine to cycle (foul, no tap strike or extra ball in the tenth frame). I want to add a circuit between the I/R unit and the relay so that whenever the beam is broken it triggers the relay to cycle the machine. Ideally it would do so after a 3 second delay but I don't think it is that critical. Can anyone point me in the right direction or give me an idea how I can accomplish this?
     
  2. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    I don't think this will be too difficult. A 555 in monostable mode should be able to do this, probably hooked to a MOSFET, opto-isolator, or similar to activate the relay.

    Some questions first:

    1) What is the part number of the relay? Failing that, what is the coil voltage?

    2) What is the voltage across the IR sensor leads when the beam is not broken? What is the voltage when the beam is broken?

    3) Locate a ground connection on the existing circuit (where the processor is mounted and presumably where the IR sensor is powered from). What is the voltage between ground and each of the IR sensor leads when the connection is broken and when it isn't?

    4) How you do you plan to power this? If off the existing circuit, can you locate a ground and Vdd on the circuit and measure it?

    Once we have this information, we should be able to help.
     
  3. Pietenpol

    Thread Starter Member

    Dec 27, 2008
    26
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    I'll get all the information tonight. Including pictures.
     
  4. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Cool beans. This should be fun.
     
  5. Pietenpol

    Thread Starter Member

    Dec 27, 2008
    26
    0
    I've put 5v to the relay and triggered the cycle on the machine. I also have approximately 24 volts within the control box that I could step down for my power. The I/r unit is on the lane. The processor box is mounted 8 feet above on a wall and the relay is inside the control box in the back of the machine. As I said, pictures forthcoming.
     
  6. Pietenpol

    Thread Starter Member

    Dec 27, 2008
    26
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    This layout has the back control box mounted on the curtain wall (the box with all the switches). Normally this unit is level with the top of the machine about 8 feet back from the wall. The big box saying ACCUSCORE is where the processr for scoring is. Ball detect is straight down on the lane. The chassis with 28 on the side is the machine cpu basically.

    [​IMG]
     
  7. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    So the relay has a 5VDC coil, is this correct? I just want to verify that is the relay's true coil voltage rating.

    So it's not practical to use a meter to check the voltage from the IR sensor to the main circuit as they are far apart. Do you think you can determine which wires from the main circuit go to the IR sensor and check the voltages from the main circuit?

    Checking the voltage across the sensor gives us an idea on the voltage drop across the sensor. Like an LED, the sensor will have a voltage drop which will change based on whether the beam is broken or not.

    Checking the voltage from the circuit ground to each pin of the IR sensor will allow us to determine what voltage is feeding the sensor.

    Both of these bits of information allow us to determine the best circuit to use for your application. We may instead go with a comparator circuit, but we'll see.
     
  8. Pietenpol

    Thread Starter Member

    Dec 27, 2008
    26
    0
    This is the ball detect unit on the lane.

    [​IMG]

    The circuit board for the unit.

    [​IMG]

    The relay board in the control box.

    [​IMG]

    And the specs for the relay.

    [​IMG]
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The LM567 is a tone decoder. Pin 8 is an open-collector output that is connected to ground when an input signal is present that is in the passband.

    Pin 7 is gnd, pin 4 is +V.

    See what you get when measuring across pins 7 & 4. See what pin 8 is relative to GND, both when the unit is receiving an IR beam, and when the beam is blocked.
     
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