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Photo Gate 2i (assembly required)


We've designed a PCB and housing for the original breadboard version of our interrupter photogate trigger. The simplicity of the trigger makes it especially suitable as a student project and for use by teachers in workshops.


The Photo Gate 2i is powered with a 9-V battery that is mounted on the outside of the 3x2x1" box for easy access. A red LED indicates the state, blocked or unblocked, of the photogate beam. See Photo 1. A single RCA output is used for connecting the trigger to a flash unit. Note that a flash trigger cable is needed for the connection. See below.


The interrupter is soldered directly to the PCB, thereby simplifying assembly, and passes through a hole in the box on the side opposite the label as shown in Photo 2. On this same side, there is also an access hole for sensitivity adjustment for the rare occasion when that is needed.


In use, the trigger is mounted or clamped in place to allow the triggering object to pass through the interrupter. The object could be, for example, a drop of liquid or a plucked cord. In most situations, one will want to delay the discharge of the flash unit. This is accomplished by connecting the output of the Photo Gate 2i to the input of a Delay Timer.


$29.95 - PG2i Kit, unassembled

Photo Gate 2i front

Photo 1. Label side of the PG2i

Photo Gate 2i back

Photo 2. Sensor side of the PG2i

Photo Gate 2i

Photo 3. Side view of the PG2i


Parts list

Assembly instructions

Flash Trigger Cable Kit (RCA type)

Hot shoe adapterThis kit is for preparing a cable to connect the flash output of a trigger to a PC jack. The kit includes a PC-type connector for the flash, an RCA plug, 3-ft of 2-conductor cable, and heat-shrink tubing. Assembly is required. If your flash unit doesn't have a PC jack but does have a hot shoe, the hot shoe adapter shown to the right can be used together with a flash trigger cable for flash triggering.


If your flash unit is one of the Vivitar models 283, 285HV, or 3700, you'll need a Vivitar PC-1 cord to connect to your flash unit. Click here for one possible source. If you're triggering your flash wirelessly or your flash unit has a 3.5mm synch jack, see this page for 3.5mm cables.

PC flash trigger cable kit with RCA plug RCA flash trigger cable, assembled

PC cable kit with RCA plug,

unassembled - $4.95

PC flash trigger cable,



Select a flash cable kit $4.95), a hot shoe adapter ($9.95), or a combination of flash cable kit ($13.90). The latter combination saves you $1 over purchasing the items separately.

Select option

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