Led flashing off AC current, any takers?
Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=28001
Printed Date: May 10, 2025 at 9:32 PM
Topic: Led flashing off AC current, any takers?
Posted By: Dauber
Subject: Led flashing off AC current, any takers?
Date Posted: March 08, 2004 at 6:27 PM
Got a custom job to do, and my customer wants to run led's to flash with the tach signal, whats the easiest, most painless way to do this?
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Kyle@Audio Obsession Sound
Replies:
Posted By: auex
Date Posted: March 08, 2004 at 7:27 PM
Describe more in depth what he wants the led's to do exactly.
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Posted By: Dauber
Date Posted: March 09, 2004 at 10:40 AM
Pretty much he wants to have LED's in his scoop, its a 1932 Ford custom with a 350 chevy engine in it, beautiful car, we are putting a custom stereo in it, loooks pretty good, now he wants the led's to alternate in the scoop with the tach signal, possible?
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Kyle@Audio Obsession Sound
Posted By: Mad Scientists
Date Posted: March 12, 2004 at 5:46 AM
Not sure what AC current has to do with this, but what I would do is either take a signal off the tach lead (on a Chebby coil-in-cap HEI it would even be called TACH on the distrib cap), or use injector pulse. Using the tach signal would give you a RPM based signal, while using the injector pulse would give you RPM based PLUS changes based on throttle inputs, ie. matting the throttle would make the lights get real bright even before the rpm picked up.. incandescent bulbs might be better for this though.. Does he just want a glow coming out of the scoop, or does he want the individual LEDs visible?.. How many LEDs are planned on being used? Regards, Jim
Posted By: Dauber
Date Posted: March 12, 2004 at 10:22 AM
Its a carburated engine, pretty much in his scoop he wants the lights (LED's) to alternate with the tach, so flicker with the speed or pulse of the tach signal.
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Kyle@Audio Obsession Sound
Posted By: Mad Scientists
Date Posted: March 12, 2004 at 5:00 PM
depending on the type of igntion system being used I'd probably start by wiring up a LED and wiring it to ground on the negative side of the coil. See what that does.. might have to use a power transistor and use the negative side of the coil as a trigger. By alternate do you mean that he wants them to wig-wag? Just a little bit more circuitry if that's the case. Regards, Jim
Posted By: Dauber
Date Posted: March 12, 2004 at 6:15 PM
What do you mean by wig-wag? Basically wants them to flicker or pulse would be the best way to describe it. Basically can hooking up an led pack(built in resistor etc) to the coil, will it work or blow up the led's?
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Kyle@Audio Obsession Sound
Posted By: Mad Scientists
Date Posted: March 13, 2004 at 7:16 PM
Wig wag means lights that alternate.. best example would be emergency vehicle headlights.. Yes, I'd try first wiring up an LED to coil negative.. battery positive to the LED package and negative to coil ground.. see what happens. Regards, Jim
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