I have a front control panel, that has it's own 7805 reg running it. 12v in, with 100uf elect and 0.uf poly caps either side. My usual setup.
This 5v supply runs some illuminated led buttons and 4x 8 digit LED displays with a Max7219 controller on board.
They work fine, but are introducing noise on my ground line, which is creating noise through the amplifier back in the main control box.
If I unplug just the displays, the noise immediately stops.
I have put ferrite coils on the supply lines, and caps directly onto each MAX7219 module, but the noise persists.
I have no options to add a separate 12v power supply (no room and the unit has only 1x 12v input), so I need to eliminate it.
Anyone else had issues with these modules? Any ideas for other isolation methods?
Help would be gratefully appreciated.
Oh... and this forum doesn't seem to work in Firefox? Login features are missing