Ed's Light Box

I've received two requests for my LED light box; I'm flattered :-)
Attached, I've scanned my circuit. Basically, I use three 10K potentiometers to create an analog signal which is read by the Arduino. That value is scaled and then fed to the PWM outputs on the Arduino. In turn, these outputs drive 3 logic level N channel enhancement mode Power MOSFETs.  These are terrific devices for this kind of work-- slammed on hard with just 5 volts, source to drain resistance is measured in milliohms, and can handle high currents. I use a CEP8030L because that was what was available on ebay. There are multiple devices which fit this requirement-- just look for logic level N channel MOSFET, and make sure the specs fit your needs. Because I am switching the MOSFET fully on and off, there is virtually no heat dissipation on the device and a heat sink is not needed.  The Arduino code has one peculiarity-- if the analog reading gets too low, the A->D converter in the Arduino has some jiggle and the LED can flicker.  Thus, if the value of 1 is reached, I set the output of the PWM output to LOW and the LEDs are really OFF.

LEDs are 3 LED surface mount modules, typically used for display lighting. They are very cheap. I use three banks. One bank is on the underside of the top of the carton. When closed, it is a ceiling light. I have a second bank placed such that they illuminate the upper part of the object to be scanned, and a third bank placed such that they illuminate the lower part of the object to be scanned. The LEDs are placed such that they illuminate the front of the object; there are no lights on the rear wall. Not only does this reduce the number of LEDs needed but there are no light shining directly at the camera.

Here's what a typical listing for the modules look like. They usually have sticky tape on back, and they are cut apart from each other with a sharp blade. Obviously, the wires must be cut and prepped as well.

The Schematic and Code are supplied as attachments.

This may sound a bit silly, but I have benefited greatly from forums like this over the years and rarely have an opportunity to give back. I am super glad that I can!

Happy to answer any questions.