Instructables

Can i use a cheap PIR sensor to trigger a camera flash?

Hi there, I am living in Panama and i need to improve security around my house. The postal service is unreliable so i will have to make do with very basic components. I'm pretty practical but haven't a clue how to get the two to "talk" to each other. If you were going to burgle a house and a decent flash fired as you approached you would be temporarily blinded, you probably wouldn't know accurately where the flash came from to sabotage it. You wouldn't know if your picture had just been taken etc etc. I would think it would be a pretty good deterrent. Thanks for any help, ppinny,

Yes, you can use a PIR sensor module to trigger a camera. I am working on one right now. You want a sensor module (not just a sensor) that allows you to obtain the conditioned digitized sensor output.

Take a look at http://www.instructables.com/id/Re-purposing-an-Air-Wick-Freshmatic-Compact-i-Moti/ it should give you some ideas.

If you wanted to use only "hacked" modules, you could make one using the recycled flash from a disposible film camera, the PIR sensor module from an Air Wick air freshener, and a digital key chain camera from either the drug store (US - Walgreens) or eBay.

To connect the modules, you need to share the ground between modlues, and wire a seperate PNP transistor (almost any will do) across both the flash module trip switch and the key chain camera shutter button. You should have a limiting resistor in the in series with the base lead of each transistor. Add a capacitor in series with the resistor (end near the motion sensor) to provide some isolation of the PIR module. The flash and camera will be activated every time the motion sensor detects a motion. Since these 3 modules each have their own batteries; flash unit has 1 AA, the camera has either 1 or 2 AA or some button batteries, and the air freshener use 3 AA, battery life should be acceptable.

If you want to have the unit only flash at night, a photo transistor or diode can be incorporated into the circuit. 

Another idea is to remove the IR filter from the camera and use IR diodes as a flash. This way there would be no flash at night to alert the intruders.  

The Parallex module is available in US from Radio shack and costs  $10. It is a nice module and would also do the job for the motion sensor.

I hope this gets you started.
The Wizzard4 years ago
The simple answer is YES.
The PIR must have a NO (normally open) contact set !
SInce some camera flash units are not potential free on the contacts, ensure that the relay connections do not make contact with anything else in the PIR.
Bear in mind that the flash might trigger several times in the course of one night, and this will drain the batteries. A regulated power supply connected in place of the batteries is suggested. It should be able to deliver surge currents around 600mA.
My suggestion is to get the PIR (with NO contacts) to activate a low level buzzer inside the house, to warn you of an intruder. This way you can be prepared for a pending violation.
NachoMahma5 years ago
. You should be able to modify a PIR security light with an interposing relay to trigger the flash/camera.
You could use the http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/pir/List/0/SortField/4/ProductID/83/Default.aspx with a transistor to trigger the flash. I would use a few because they are so cheap.