Tech. question?

Modeling Subjects Science Fiction
1

I need to know what size resistor I need to drop a 9v-batt.down to a max. of a 4.5v led without frying it.Ohmns’ law was a long time ago for me!Thanks.

2

Assuming a current of 20mA you need a 225 ohm resistor. A current of 30 mA and you need a 150 ohm.

Personally, I stay away from 9V batteries. They have the lowest current capacity of common batteries. I suggest AA’s or AAA’s.

Scottie

3

Thanks,Scottie this helps alot.