INGO Electrician Question

[Militarypol21]

INGO Electrician Question:

I’m in the process of making Angel Eyes for the Dodge Charger.

Video I’m going off of:
[ame]http://www.youtube.com/watch?v=0JSMQk61xQ8[/ame]

I did a “test” light the other day and it works just like the video says it would…. Well to an extent. I hooked mine up to a 9v battery using a resistor (red, black, black or possibly black, black, red – I don’t know how to read these). My question is what size (color) of resistor do I need in order to wire this into a 12v power supply? I’m using two 5mm High Brightness White LEDs

(12VBattery)------------(Resistor???)----------(LED)------------(LED)

 

[1911Shooter]

I am electrician but I will be honest that I am not that great with the resistor color codes. I dont have to use them enough to remember it. I will make a suggestion though. Wire it in with an inline fuse. This will prevent it from doing any damage that may occur without it. Also you may want to talk to an auto mechanic. I know form experiance that electricians normally do deal with resistors and 12V power supplys that much, that is normally done by the engineers. I will check and see if I have any of my books on resistors and see if I cant figure it out for you though. It may take a couple of days considering I will have to dig to find my books, but I will look and if I find anything I will send you a pm with the info.

Good Luck

 

[Militarypol21]

I am electrician but I will be honest that I am not that great with the resistor color codes. I dont have to use them enough to remember it. I will make a suggestion though. Wire it in with an inline fuse. This will prevent it from doing any damage that may occur without it. Also you may want to talk to an auto mechanic. I know form experiance that electricians normally do deal with resistors and 12V power supplys that much, that is normally done by the engineers. I will check and see if I have any of my books on resistors and see if I cant figure it out for you though. It may take a couple of days considering I will have to dig to find my books, but I will look and if I find anything I will send you a pm with the info.

Good Luck

Good idea with the fuse. I never considered that. Thanks, any help with resistors will be great. I googled "resistor color codes" and am now more lost haha.

 

[x10]

If your using your Car battery you kind of have to count on 14Volts so you need to size resistor for 14Volsts, it wouldn't hurt to put a 24V Zener Diode on it also but you need R= V/I so assuming your LED is a 20 ma LED you need R = 14/20ma = 700 ohms, in standard 5% resistors your going to have to take a750 ohm I would go 1/2 watt just because the size may help you in durability I don't know how your going to do the resistor but if you put it in heat shrink it will be more durable. the reisitor code is Violet Green Red, hope this helps,

get a pwm circuit and do wierd things with it

 

[1911Shooter]

Yeah the color codes are not my strong suit either. It looks like someone has your answer though so good luck. I will still check my books also. If you get another answer that is like X10's though I would probably trust them over me. The color codes kill me.

 

[x10]

Resistor Codes - Transwiki

 

[Militarypol21]

Resistor Codes - Transwiki

I understand that the color corresponds to a number but the one I currently have (that I took out of an old LED flashlight) is black | black | red or it could be red | black | black, depending on which way you flip it.

But as long as I get a Violet | Green | Red you say it will work for that much voltage and for what I am wanting to do, correct?

 

[x10]

yes, if you don't get at least 650 ohms or greater you'll put too much current through the LED, if you go much over 800 ohms the LED will be dimmer than if it was getting full 20 ma of current.

Radio shack used to sell things like resistors but I dont' know now, If you can't find any let me know and I"ll throw a couple in an envelope and mail them to you

 

[Mr Evilwrench]

Um, no on 700. You have to take the 14V minus the drops on the two LEDs, which depends on the color. Most do run at 20mA. Reds drop about 1.8V each, so you'd be 14-3.6=10.4V, then divide by .02A, for 520 ohms. 510 (green/brown/brown/gold) is a standard 5% value. P=current squared times R, so .0004 x 510= .204 W. a 1/4 W would handle it, but probably a half. Different color? Have to recalculate.

 

[x10]

stay with with what Ioriginally said most system for run at16 volt you need the estes protection from the dirty alternator and the half watt resistor is for mechanical reasons

I've ben doing automotive electronic system for 25 years you need margin