I'm doing a feasibility study for a large (27 x 46) matrix display, but despite trawling the web for a few days I can't find any examples of circuits I can base my design on. I have a very crude knowledge of shift registers (I have a simple 8x8 LED matrix working happily in a breadboard) but I can't find any clues on how to build exactly what I want.
The problem is I DON'T want to use LEDS! :astonished:
I have a tonne of 10ohm SMD resistors and want to mount these in a matrix under a sheet of thermochromic film. The resistors warm up nicely with the tiniest voltage through them and show up as a rainbow spot on the thermochromic sheet. I'm guessing there'll be sneaking paths in the matrix and resistors around the selected one may 'illuminate' at quarter brightness, but as this display is for artistic purposes it's not much of an issue. That, and I don't really want to spend £100 on 1242 SMD diodes!
I have a handful of ULN2003As, and have been trying to introduce these into my typical LED matrix circuit to see if I can get more power in, but applied to the anode or cathode side, the Arduino just crashes and resets. I'm getting the extra voltage from using an external supply and pinning the ULN2003A's COM to the Arduino's Vin, which has worked fine in other projects.
Any input would be very greatfully received,