I am using a 555 Timer to generate a 38Khz IR signal from the same battery as the electronics in my RC Car. Whatever combination of capacitors I try I cannot eliminate the electrical noise coming from the 555 Timer (its switching about 30ma).
What you really want is a "PI" LC filter. This consists of two capacitors across the power lines, with an inductor between them, in the shape of the greek letter "pi":
The 7805 is a perfect answer ..... Try the Pi filter though
I have a solution, its the 7805, but if I had a scope I would still be working on a passive approach.rcarduino.blogspot.com
I have a diode where my power enters the board, why do you think a diode will help ?Duane Brcarduino.blogspot.com