# how to know the electric stream(amp)

hey guys,

when i 5V from arduino is to much for a component you have to reduce it with a resistor, but to calculate the which resistor you need you have to know the stream. How do i know the stream? In one example it was 20mA, is it always that much?

Thanks :D

i think you can draw a maximum current from 5v is 500mA

I think your translation is incorrect. "Stream" = "current."

Well, you would have to read the datasheet for the component to find out the current. But the only current-controlled devices you are likely to come across are LEDs. Then you can choose any current you like, up to the maximum, and make it as bright as you like.

Basically every other device you will see is voltage controlled. Give it the correct voltage that it asks for in its datasheet and it will only draw the current it needs.

The answer is entirely dependent on what you are connecting, so there is no single answer. If you can give specific components, we can demonstrate the full procedure.

20 mA is the maximum recommended current to draw from an Arduino pin. You arrange the resistor to allow whatever current is required up to that value.