I have terrible color vision. I fail the Ishihara tests [
www.toledo-bend.com] every time.
Fortunately, there are only a handful of common resistor values. The first two color bands are almost always:
brown black = 10
brown red = 12
brown green = 15
brown gray = 18
red red = 22
red violet = 27
orange orange = 33
orange white = 39
yellow violet = 47
green blue = 56
blue gray = 68
gray red = 82
That covers the 20% and 10% tolerance resistors. There are other values (for 5%, 2% and 1% tolerance) but you hardly ever come across them. I've got those 12 combinations memorized, so I can pretty much figure it out by process of elimination. For example, if I see something that looks like gray blue yellow (860k), I know it's really green blue yellow (560k).
Another handy thing is that the third band is almost never blue, violet, gray or white, which narrows down the possibilities quite a bit.
The hardest for me to tell apart are brown green and brown gray. I usually have to pull out the meter for that.
Edited 1 time(s). Last edit at 08/16/2008 08:00AM by Steve DeGroof.