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Tech. question?

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  • Member since
    November 2005
Tech. question?
Posted by Anonymous on Tuesday, January 11, 2005 8:54 PM
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.
  • Member since
    November 2005
Posted by Anonymous on Thursday, January 13, 2005 8:26 AM
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
  • Member since
    November 2005
Posted by Anonymous on Thursday, January 13, 2005 11:04 AM
Thanks,Scottie this helps alot.
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