LED Fade In and Fade Out

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=82125
Printed Date: May 07, 2024 at 4:50 AM

Topic: LED Fade In and Fade Out

Posted By: magicmikey2
Subject: LED Fade In and Fade Out
Date Posted: August 27, 2006 at 3:05 PM

I just installed a car alarm in my vehicle (Crimestopper 2016FM) and I'm going to change the stock red LED to a bright white one. I might as well add some cool factor to it instead of just make the LED constantly blink when armed.

I would like the LED to fade in and out while still blinking. I found multiple circuits on the Internet such as this one:

posted_image

I'm wondering if there's a way to simplify this a little bit just by using caps and resistors...

Don't get me wrong, I have all the parts needed right here ready to solder it up but I have a feeling there's an easier way.

Thanks.

Replies:

Posted By: magicmikey2
Date Posted: August 27, 2006 at 3:23 PM

I think I'm in error here. I haven't tested the output from the module yet, so I don't know if there's 12vdc coming out or if it's less than that since I don't see a resistor connected to the LED. Another I don't know is if the voltage is coming out like 12v-0v-12v-0v or if it's a constant.

After thinking about it, is all I need is one capacitor?

Thanks.

Posted By: magicmikey2
Date Posted: August 27, 2006 at 5:23 PM

Ok, I just read the LED output from the alarm module and it does in fact read 12v-0v-12v-0v constantly. I don't think I need a chip, just caps and resistors... any help would be appreciated, thanks.

Posted By: dias_ryan
Date Posted: October 06, 2006 at 11:33 AM

led's typically only change intensity about 10 %.

A propper fade would require a PWM signal that changes with respect to time.

If you dont' know what PWM is it stands for pulse width modulation. IE, makes the led blink much faster then you can see, and changes the on verses off time. such that, it starts on, starts blinking with very very short offs, then gradually blinks with longer and longer offs till it stays off.

theoretically you dont' see the Blinking (pwm signal) and only see the led get less intense.

A LED is a digital componet and will not fade. Not unless it was designed to.

After i replaced my dash lights with blue led's.. i noticed my dimmer no longer works. It goes on.. or off as you vary the dimmer switch.