Another old project that I recently dug up and want to complete is this REALLY powerful invisible infrared spotlight.

I chose 940 nanometer infrared LEDs for the job as they are completely invisible to the naked eye.  I should insert a WARNING here:

If you are thinking of replicating this project, you need to be aware that it is uncertain if very powerful IR light like this can damage the retina in the eyes of humans and animals.  Therefore, the best thing to do is to be cautious.  DON’T look into the IR beam directly.

DON’T point the beam at people or animals that are close.  No-one wants eye damage.  Safety first, last, always.

Building the spotlight was an interesting project.  It uses 304 infrared LEDs that emit infrared light in the 940 nanometer range.  The LEDs have a beam angle of 15 degrees, so the light is reasonably focused without needing a lens on the front of the unit.

It has a light sensor in it, so that it automatically turns on in low light conditions where a wildlife cam, or CCTV camera might need extra illumination.

I also added a fan to the enclosure as the density of the LEDs lead to a fair amount of heat being generated!

The power supply to the unit is 24 volts to keep the current draw down, so there is a 24 to 12 volt transformer in the housing as well to run the cooling fan.

Testing of the prototype went well, the LEDs are seriously bright and made for very effective illumination in total darkness.

I came across an old sketch that I made of the housing, so I thought I would add it in.  I have another set of  LEDs mounted and soldered in to another board to make a second unit one day, so it’s good to have the original housing drawing.  Note that the cooling fan ended up on the back of the unit rather than the top as suggested here.

I will post more about this project in due course.