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Need help doing a timing system for UR3

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  • Need help doing a timing system for UR3

    I looked at the site and found it a little confusing to read so I thought I post here.

    I'm going to use Radio-Shack PN: 276-145 infrared photo resistors under my track. Now, do I need to use PN: 276-143 infrared LED or can I use PN: 276-316 Blue LED 2600mcd for my light bridge above? Also, do I need to put any resistors inline anywhere, and will the computers parallel port supply enough power for either of those LED's for the bridge?

    The Blue LED 2600mcd is 3.7 volt 10ma and I was going to have 3 of them since I'm making a 3 lane track.


    [EDIT] Found out I have to use the infrared LED so I just need to know if those can be powered by the parallel port on the computer, and if I have to put a 470 ohm 1/2 watt resistor in line for each LED.
    Last edited by Moonbiter; 01-10-2007, 08:22 PM.

  • #2
    Hi there

    Normally you do not power the IR diodes using power from the PC - instead buy a cheap power supply and use this instead - could be a 5 volt DC - in order to reach your desired voltage you would then need an additional resistor of approx 150 Ohm to make it work (will give you arrnd 2.3 volts)


    If you are building a new track could suggest using a different kind of detector which has both IR diode and receiver in one - works like a charm



    • #3
      This is a complete new build. Is the kit you are talking about PN: 276-142 from radio shack?

      I have a 12vDC 1000mA power supply I can use for the LED power. From what I seen, I need to use a 470 ohm 1/2 watt resistor for use for that. Is that correct? My electrical skills are severely lacking. I'm going to need to take a class in electronics again to get familiar with all this again.


      • #4
        Hi again

        Will revert on the size of resistor- here is a link to the "thing" we are using

        Site is in Danish, but should be available worldwide


        • #5
          Home made light bridge using Radio Shack 276-142

          Hi. Here are some photos of my home made light bridge using the Radio Shack part 276-142. I used 2 AA batteries connected in series to make 3 volts and used a 16 ohm resistor to power the infared emitters on a 2 lane track. The batteries should last for months. So far 1 month of use.


          • #6
            Nice. I got mine "working" I wired up a single set to make sure I had my wiring correct and made sure UR3 was able to read it, and it worked. I'm using a 12vDC power supply and using 470ohm 1/2 watt resistors to bring down the voltage. It's a little over kill but it doesn't heat up to much.

            Any pics of placing the Photo transistor in the slot? That's a pretty nice gantry you made btw and I never thought about using some batteries.


            • #7
              Sensitive to light

              So I'm just putting my track together...... Does the photo resistor work with the straight LPT power?.... Just wondering if I need to worry about it - boost it/cut it - whatever.... My PC sits about 7 feet away from where the timing bridge will be......


              • #8
                Need help doing a timing system for UR3

                hi,Total weight of the lead is probably only around 3g: pretty minor. You would notice the narrow strip of lead stuck to the roof of the car in the "notch" in the black interior.
                As Wet said: YMMV and no two cars ever react the same way and life is never simple enough to have one single easy answer. As someone said: all complex problems have simple, easy to understand, wrong solutions! This seems to have worked for me so I am at least a happy camper