Okay, NoObisch Q, I wonder how I would know how many Ohm a resistor should be, when I am designing a circuit on my own. Like the KnightRider example, they use 220 Ohm, why (and why use a resistor here anyway??) I am also using Google offcours, but here I have a feeling I can ask stuff I don't get…

How do I know what resistor to use??

system September 22, 2006, 6:52am 8

sorry:

I = V/R = 5V/1kOhm = 5mA // how do you get 1mA?

you are right. my fault. sorry