I need an electronics guru

[Paul B]

Ok I have some 5 volt 20 ma LEDs and I want to run them on a 12 volt power supply.
How many ohm resister do I need to make that happen?

My electronics school was way to long ago to figure this out.
It is not for the tank, it's for my boat.

 

[Audi0s]

If you PM olivier he can probably help you. He knows his stuff.

 

[The_Codfather]

If you PM olivier he can probably help you. He knows his stuff.

+1

 

[Olivier]

i am not a guru.
V = IR
V = 12v
I = 0.020A
R = V/I
R = 12.000V/0.020A
R = 600 OHM.

I would use a 1/4W resistor or even 1/2W resistor
you can hook up 3 - 5V LEDs to a 12V power supply and it would work even not fully hot however last longer.

look into your led spec. and find out what is it forward current (20mA max in ur case for continuely on) and forward voltage. you dont' want to go beyond these values

 

[Tazmaniancowboy]

i AM not a guru.

;D

 

[Joejoe]

Radio shack sells step down voltage regulators. Much easier than using resistors.

 

[REEFLECTIONS]

i heard olivier chatting electronics wit fisheye at a meeting... had to walk away cause my head was spinning

 

[Paul B]

OK thanks guys, I got it figured out. ;D