Hi! I'm powering a bunch of 12v leds via my arduino using a ULN2803 transistor chip. I'm also having the arduino talking with a 4017 to chase a bunch of smaller (3v) leds. I have used a 7805 to regulate the 12v to 5v so I can power both these lighting arrays. Is this good practice - using a 7805 in certain places while also utilizing the original 12v supply to power other things in the larger circuit?

 

Is this good practice - using a 7805 in certain places while also utilizing the original 12v supply to power other things in the larger circuit?

Of course it's legitimate to do that; why in the world wouldn't it be?

 

Thats good - tis what I thought. Just having some buggy behavior in my circuit and been spending a solid day trying to figure out "why" and thought in my delirium I may be implementing the 7805 incorrectly. The 7805 / 4017 part of the circuit is perfect, just leakage between two 12v LEDs and I see absolutely nothing in the circuitry/panel mounts that would create a short. Tested continuity w/ multimeter. Gonna just roll with it. I have been smearing flux paste all over everything lately. Maybe that's the foolish?!

 

The flux might be causing the leakage. I once unknowingly bought and use some acid-based flux -boy did that ever make soldering fast and easy! It also created a lot of leakage on the hand-build bard. I must have used half a liter of alcohol getting it off.