Ah, that explained a lot, but it's still glitching for a bit now..
By the way, i connected a 7805 to power the tlc's
the wire from the 5v-out from the arduino was still connected to the powerlane in the breadboard, and now the 7805 is powering the arduino through the 5v out pin on the arduino. Can that cause any damage or anything?
Pretty much exactly like this
and make sure TLC5940.o is deleted afterwards?
The led's were only getting 2.5mA because they were getting insufficient voltage.
There's no glitching whatsoever, even without capacitors, if I power the power supply down to ~11v.
There's a lot of glitching, even with capacitors, when I power the power supply up to ~12v and above.
So what current had you set the TLC5940 for?
I presume this is because the current being switched is larger and it is generating interference and you have insufficient decoupling on the supply to cope.
But I already have .1uF capacitors at each chip, and 10uF at all breadboards.
How can I, preferably step by step, decouple the noise I've got now?
No amount of decoupling capacitors can rescue a bad layout.
The layout I had with the glitching was:
I have now however rewired everything to be a bit more compact,
and I had to put some very small capacitors on the end of the LED run.