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IR Night Light for CCTV homemade automatic
Very simple circuit, the LDR (light dependent resistor) gets more conductive, the more light it see.
this way it turn off the FET at day time, most LDR types are not sensitive to IR
Easy to test with IR LED and ohmmeter, if your LDR react to your IR, then paint it light blue with a permanent marker,
then it only see sunlight as wanted
If your cam is less sensitive, you might need to repeat the 8 LED and 82 ohm resistor,
simply add as many as you need for the cam and distance.
one row as shown here is about 0.2Watt usage, 12V and 20mA.
The capacitor handle blinking light from flurecent tube light, if any of this is nearby at night,
and its level is close to the trigger point, you clearly see why you need this capacitor.
The type of IR LED to use for this project is 800 to 850nm wavelength, they are NOT the types used in IR remotes 900-950nm,
you should see a weak dark red glow from the led, note a "remote" type IR led is not visible by the eye at all.
My camera is an ultra low lux type from RangeVideo.com
RunCam Owl 700TVL Starlight FPV Camera True 0.0001lux FOV 150
This cam it is also very sensitive to IR.
Here at night time, this 0.2 Watt IR, make it perfectly fine to see what is going on in my back yard.
Note : some types of CCTV cams are not sensitive to IR at all, simply remove the IR filter glass from its inside,
expert disassemble skils might be required, it is a light blue glass disc you need to remove,
some even glued this disc directly to the CCD sensor, if this is the case, give up, and get another cam.
after filter removal, if you see day pictures looks a bit too red now,
to fix this turn automatic color balance off, and manually turn down the red a bit until you see a perfect picture again.