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Sound Trigger 2 (assembly required)


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


The Sound Trigger 2 is powered with a 9-V battery that is mounted on the outside of the 3x2x1" box for easy access. A red LED indicates whether the trigger is on or off. 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 piezoelectric sensor 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. In use, the trigger is placed on its side near the source of sound. As for any sound trigger, the delay between the production of sound and the discharge of the flash unit is determined by the distance between the source of sound and the sensor. Thus, a synchronizing delay isn't required. If, however, one wishes to generate a delay electronically, the output of the Sound Trigger 2 can be connected to the input of a Delay Timer.


$29.95 - ST2 Kit, unassembled

Sound Trigger ST2 front

Photo 1. Label side of the ST2

Sound Trigger ST2 back

Photo 2. Sensor side of the ST2


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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