I have a small problem. I have a circuit with an 1157 bulb in it, and I took that bulb out of the circuit. Now I need to replace it with a resistor that will provide the same amount of ohms and amps as the original bulb. Can anyone tell me what kind of resistor I need?

 

Is it a Stop and Tail bulb 5w/ 21w

what is the current and voltage rating of the bulb?

if so I= W/V
R=V*V/W

21W/12V= 1.75A = 6.7ohms

5W/12V=0.42A = 28.6 ohms

 

My reference doesn't list the 1157 bulb, but somewhere there is a reference that gives the voltage and current ratings of that bulb. Seek and ye shall find. Otherwise, put it back in the circuit and measure the voltage across it and the current through it. Then apply Ohm's law.

 

Hello,

A simple search gave this site:
http://www.nextag.com/1157-bulbs/shop-html

Various brands may have various ratings.

Bertus

 

A simpler search gave this: Automobiles require the correct current through their tail lights or they will throw an error code. Trying to change automotive parts to fool the computer into not throwing an error code is forbidden by the Terms of Service on this website. Please do not use this site to learn how to modify automobiles.

You can find a link to the Terms of Service about 2 inches below the box you type in or 5 inches below the box you are reading (unless you have a smaller monitor than I have).

Thank you for your patience.