TTv1 and crossed passive infra-red sensors

We've had a few emails asking about how to make the Triggertrap v1 trigger a camera when there is motion detected in some small area of space that the camera is pointing at. This has a million possible applications, but could be especially useful for wildlife photography, for example: capturing a shy critter or a bird in flight. Haje posted about making a Triggertrap motion sensor back in March,  and now Darren Newman, one of the members of our community on the Triggertrap forum, has come up with his own version (and provided brilliant documentation).

Triggertrap v1 has an AUX port, which accepts a RCA jack. What this means is that if you can use something to create an electrical signal, you can use it to trigger your camera via the TTv1.

A Passive Infrared sensor (PIR) is a very simple device which detects the infrared radiation emitted by all objects. To use it for motion detection, the sensor is set to detect abrupt changes in temperature at a given point. As an object, such as an animal, passes in front of the background, the temperature at that point will rise from whatever the baseline was to body temperature, and then back again. This quick change triggers PIR sensor - which, when hooked up to a Triggertrap Mobile, also triggers your camera!

The area over which the sensor works is quite broad, so to better localise the motion used to trigger the camera, Darren used two sensors connected in series so that the trigger would only go off  when both sensors detected movement. By playing around with the placement and orientation of the sensors, you can get quite precise results, and even select for movement in a particular direction.

Here's a summary of his process (all images except the first belong to Darren Newman):


According to Darren, the units have a 3 metre range of detecting movement, which means they're quite wide, and won't be able to be used for precise and instant capture, like for example a moving bullet. But with some experimentation with the positioning, this set up will work quite well to photograph birds, or anything else that moves at a reasonable speed. You could also try experimenting with narrowing the sensor beam by using a cylinder around the sensor to block signals coming from the sides, for example!


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