Can anyone please calculate the color code for a 9v DC Resistor. Its the last thing I need to finish my whole project.?

I'm trying to light up the dash in my truck and everything is ready except im plugging it in to the 12v DC cigarette lighter and I know it will blow them all sky high but I already tested and 9v DC is what I need. Thanks in advance!!! 

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lemonie6 years ago

This is a question people as often enough, other people do a bit of scripting and produce lovely pages like this to answer it:
http://led.linear1.org/1led.wiz
http://led.linear1.org/led.wiz

L
Why not read a bit on the topic you are doing your project on? Any school Physics book has it. I know I sound rotten, but I can't help it.
Re-design6 years ago
Resistors don't have voltage ratings like that. What size resistor you need depends on how much current your light are going to draw.  Another problem with using a resistor is if the voltage changes your lights will dim or burn out as the case may be.

If you need 9 volts and you are starting with 12-13 volts a better way is to get a voltage regulator that is rated at 9 volts or a variable regulator and adjust it to 9 volts.  That way if your alternator puts out a little bit more you won't over power your light and if it puts out a little bit less your lights will still get the full 9 volts. 

This circuit should work fine.  just sub. your battery for the wall wart shown.  The chip is available for as little as 45 cents.  Radio Shack usually has then in stock.
*best answer. Also worth noting is "consider reading up on ohm's law".
*best additional info.