There have been several Vernier Photogate styles sold over the years.

The current style has a larger cross section than older units, and has a built-in laser gate. See the web site for an image. Photogate (VPG-BTD)

The previous style had no laser gate, but did have a detachable cable. Because of the presence of the cable port and the mounting tab, this model photogate sits a bit differently on the Centripetal Force Apparatus photogate mount.

To mount the older photogate, use the 1/4-20 captive nut to match the bolt supplied with the CFA. Position the gate at an angle, so that the cable clears the photogate mount. Tighten the gate in position to extend it as much as possible from the vertical gate mount. You may need to translate the gate mount to gain clearance between the gate and the slotted wheel.


As long as the red LED on the long side of the gate blinks as the slotted wheel is rotated, data collection will be fine.