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Building a Camera Trap


New Member
Hi there
This is my first time on this site so hopefully I’m in the right place for this question.
I am a wildlife photographer that is looking at building a Camera trap.

Basically the idea of a camera trap is an active or passive IR sensor that will trigger a camera to take a picture when the beam is broken or Motion and heat is picked up.

I first had a look at a few products on the market but they are really expensive or are built in with the camera, which normally takes a low quility picture.
As I what to attach my Digital SLR to the trap for maximum picture quality and out in the bush I will need it to be powered by a battery and then prey it does not get stolen or damaged.

I have found 2 products on the market that I want to try and replicate
Phototrap The Ultamate Photographic Trigger System and http://www.trailmaster.com/reference.php

I prefer Phototraps design as you can use a laser beam in a few different ways to take pictures.

But ultimately what could be perfect is a design that I could swap between passive and active Infrared.

My circuit and electronics knowledge is very limited but would be very thankful if anyone could provide me with some circuit drawings or ideas that could help me to build one.
Thanks for your time in advanced.


New Member
> My circuit and electronics knowledge is very limited

You know, in shops, sometimes they have a little bell that rings when the customer comes in. This is usually a light beam which is interrupted by people. To put the emitter and sensor in the same box, the other side of the beam usually is a retroreflector (a piece of plastic with a special mirror pattern on it that reflects light to its source, like the stuff that's on the safety triangle you keep in your car trunk).

You could try buying a readymade sensor like this and just replace the "ding-ding" with a transistor driving your camera's remote input.

Or build one yourself, like :

- use an IR receiver like TSOP852 : basically it detects an IR LED blinking at a certain frequency (see datasheet) and outputs a logic signal. Using a blinking led makes it easy to ignore background illumination.
- pick a transmitter led with the right wavelength
- use a 555 to blink the led
- use the logic output of the IR receiver on a simple transistor to drive the remote input from the camera
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New Member
Thanks Peufeu
Sorry about the late response, Your first suggestion is kind of what I had in mind. So If removed the "ding-dong" and replaced that with "what kind of device" that would close a switch on my shutter release.

Im going to look into your other suggestion also as that seems to give me more flexablity with timing my camera to take that picture.
Thanks again


New Member
> "what kind of device" that would close a switch on my shutter release.

I don't know what brand of camera you're using.
I have a Canon EOS 450D, to take the picture you just short the two pins on the remote control connector, which is a standard Jack.
Use Manual focus to get rid of forus lag...
If you have another kind of camera, you might have to do otherwise, (like buy an IR remote from ebay and hack that).

Simpler solution and easier to get working for an electronics noob : find a cheap IR sensor ding-dong, hack. Note you need active IR (light barrier) not passive IR (like patio lights) because the passive sensor need something big (like a robber) and has no precision, whereas you can put the light barrier on your focus plane for instance.

To connect to the camera, you could use an optocoupler. Isolation isn't strictly needed, but when connecting a $1000 camera to a cheap hack, you never know !

If you want to DIY, google "light barrier schematics". Most will probably use IR remote control receiver chips which have good tolerance to ambient light, because they use a pulsed signal.

You could do even simpler : a laser pointer, and a photo transistor at the other end. But since this doesn't use pulsed light, you will need to put the detector inside a black tube to shield it, and lasers will use a lot more battery than a dumb IR LED.
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Well-Known Member
Most Helpful Member
Looking back to your original post:

Basically the idea of a camera trap is an active or passive IR sensor that will trigger a camera to take a picture when the beam is broken or Motion and heat is picked up.
OK, you actually have a few options there. The first is the breaking of a beam. So where would you use that? My thinking with outdoor nature photography is across a path frequently traveled by subjects. Beam type devices have a downside in that the range is limited, it does improve at night. Generally the beam is transmitted then a reflector is placed. The beam bounces off the reflector and returns to a receiver. Anything interrupting the beam trips an electronic switch and triggers the camera. Nice feature is beam breaks and camera fires, beam breaks again and camera fires over and over again. Obviously the beam is perpendicular to the path but unless you want side shots the camera is at a different angle. A basic beam has no clue what the direction of travel is of the game either. You can get frontal shots as well as rear shots.

Next you have motion or heat and this is where a PIR Sensor comes into play. Think about security lights that respond to motion by responding to heat. Walk in the field of view and the lights come on or walk into the field of view and the camera fires. This type sensing opens a few new doors as we aren't limited to a beaten path. For example birds don't walk down a path. Here you work with an angle of view of the sensor and distance.

At this point you have two different sensors used for two different methods of triggering the camera. They also function on two different principals.

The bottom line here is to fire the camera and as peufeu points out you need to know what makes the camera you have go "click" and then it becomes simple (we hope) to design an electronic switch into the scheme.



New Member
There are passive IR-sensors on the market with adjustable sensitivity and activation time.

They are pretty cheap since they are mass production items.

I used one of those to open the porch door when the cat wanted to enter the house.

With an extra mounting plate on the camera tripod you'll have a "ready-to-use" unit - and since weight isn't an issue you might use an SLR-battery with sufficient capacity (2.4 Ah) to shoot series of photos.

For your application you'll just have to modify the power supply which is normally contained in the device using mains voltage.

The relay in the circuit is normally connected to mains with its common terminal, which has to be connected to your desired power source to activate the camera.

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Well-Known Member
one thing to remember-IR unless it is pulsed does not work in daylight as daylight IS IR light so the sensor is useless in daylight. MOST motion sensors if not all have a Cds cell that turns off the IR sensing circuit during daylight. Using a pulsed IR signal, it may still have problems in daylight.

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