It wasn’t bad, but I basically stripped most of the wires out and restarted anyway . The schematic shows 12 V connecting to the input pin on the lm317. In breadboard on this one the top power bus line (where the red wires connect) is assumed to be 12V from a source unshown in breadboard (in schematic I replaced the ac source with a dc source and used inspector to set that to 12V). That can be used as the raw input to power the Arduino as well although I didn’t do that (powering from a separate wall wart or the USB connector will also work fine). I replaced the breakout board op amp with the dip 8 pin op27 which has he same pin out as the dip tlc271 on the assumption you would be using a dip op amp (as opposed to a surface mount device on a breakout board as you had). I used inspector to adjust (by typing the value over the resistance value in inspector (on the bottom left)) for the 38k and 82k resistors and added the missing ground to the Arduino and with that you should be away.
elwire_fade_mod.fzz (12.4 KB)