Camcorders a generally designed for well lit scenes, using the light to create a quality color image for recording. To ensure that the image is seen by the camera in a similar way to our eyes, only the portion of the light spectrum that is visible to our eyes is processed. Infrared light falls just below red on the light spectrum, making up the wavelengths from about 750 nanometers to about 1500 nanometers. This light cannot be seen by human eyes, but it can easily be seen by the CCD imaging system in the camera, allowing it to be used as a night vision viewer.
Unfortunately, you cannot simply add an infrared illuminator to your camcorder and use it to capture night vision video because the CCD imager contains a glass filter that blocks out most of the infrared light. The good news is that most camcorders allow a secondary video input to be recorded, and by feeding the output from a small black and white spy camera into this input, you can give your camcorder the ability to record night vision scenes that have been lit by some type of infrared illuminator.
This project uses an inexpensive camcorder and a $20 black and white spy cam along with one of the LED illuminators shown earlier to create a portable stealthy night vision camcorder.
Most video camcorders allow an external video source to be plugged in, essentially replacing the built in CCD imager with some other compatible video source. This video input will often have some custom manufactured input jack with a label of “external”, “line input”, or “AV input”. You will need the cable that came with the camcorder in order to make this project as each manufacturer will have its own special cable for that model of camera. On the older tape based camcorders like the one shown in Figure 1, there was a 1/8 jack “standard”, that used a 4 ring 1/8 inch male plug like the one shown in Figure 1, allowing any composite video source to be fed into the camera.
You will have to identify both the external video input and acquire the proper input cable in order to build this project, but if you kept all of the accessories from your camcorder, then that odd cable will probably be still sitting in the box, as it usually not used. Some manufacturers like to chisel the customer out of more money by making their own special connectors and then charging a ridiculous amount for the cable, so check your camcorder manual to make sure your camera supports video input and that you can acquire the necessary cables for a fair price.