Open source physics photogate kit

Making a photogate

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Making a photogate

The photogate kit includes two pre-assembled photogates. The photogate assembly steps below are only included for informational purposes and for users intending to make their own DIY photogates.

1) Photogate rod

Use the 2 x loop clamps and 2 x 10-32 scews to attach the rod as shown in the images. Requires a hex wrench. (Parts # 1, 2 and 3 in List of hardware).


2) Gravitech RJ11 breakout board

Use the four 2-56 screws to mount the RJ11 breakout board to the photogate body. (Parts # 9, 10).


3) Laser cut sensor/led mounts

Use the 5/16” long 4-40 screws to attach the sensor/led mounts to the sides of the photogate. Orient the parts with the larger hole towards the top. (Parts # 4, 5).


4) Photogate sensor/led

Press-fit the LED and Sensor into the mounts. (Part # 8).


5) Cable covers

Use the 1/4” 4-40 screws to mount three of the cable covers. (Parts # 6, 7).


6) Wiring to the RJ11 breakout board

Cut and strip the four wires.


Using a small Philips blade screwdriver. insert and secure wires into the RJ11 breakout board as shown in the image below.

  • Phototransistor wires first (white, green) followed by emitter LED wires (black, red).

Using some of the left-over black wire from the LED component, form a small u-shaped loop and place the ends into the last two terminal blocks. This is for the auto-detect function.


7) Finished photogate

Screw on the last cable cover to finish assembly.


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