10 Leds For Status

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=82521
Printed Date: July 02, 2025 at 1:49 PM

Topic: 10 Leds For Status

Posted By: nhoj_yelbom
Subject: 10 Leds For Status
Date Posted: September 05, 2006 at 7:18 PM

i have a alpine sec-100s currently with one led, and i want to have ten total. in the manual it says i can only have 5 in series and not in parallel. how can i have all 10 working? props for any help

Replies:

Posted By: Powermyster
Date Posted: September 06, 2006 at 3:06 AM

why 10 LED's thats first question.

i'd have thought 5 would be over kill

anyways i'm sure you have your reasons. you could use you ground when armed to trigger flashing LED's problem with that is. they won't flash trouble codes. thats presuming you want all LED's to flash codes

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Why oh Why didn't i take the blue pill
Darren Power

Posted By: nhoj_yelbom
Date Posted: September 06, 2006 at 4:23 PM

its an led scanner and i wired 5 up as the manual specifies but none light up, if i remove them the one lights up. but how can i have all 10

Posted By: nhoj_yelbom
Date Posted: September 06, 2006 at 8:28 PM

my alpine manual says 5 is the most

Posted By: dualsport
Date Posted: September 06, 2006 at 8:50 PM

With only 12V driving the LEDs you probably won't be able to drive 10 LEDs with a series hookup to full brightness, because that only gives each LED 1.2V, which isn't enough.

If you want to drive 10 LEDs, you'd have to break up the connections into at least two strings, with 5 on each side, and you'll need to use an external current source circuit, since your module only outputs a fixed current at 12V. You can use a few transistors in a current mirror configuration for that-

Are you sure you're hooking up your 5 LEDs in series, when you say they don't light up that way, but one LED does? It has to be end to end, and make sure they're all pointing in the same direction, because if you have one of them backwards, they won't light up at all.

Make sure the LEDs you're trying to use are bare LEDs also; if they have built in dropping resistors and are intended to be driven by 12V directly, it won't work in the series configuration you're using. When your one LED is on, measure the voltage across it to see what you get; it should be under 3V.

Posted By: Powermyster
Date Posted: September 08, 2006 at 5:17 AM

well explained dual

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Why oh Why didn't i take the blue pill
Darren Power

Posted By: iskidoo
Date Posted: September 10, 2006 at 5:28 PM

Also wondering why your getting into wiring each LED in a scanner. Is this a pre-built LED scanner or something your making from scratch. Any pre-made scanner should have it's own circuitry. Just curious as to what your calling a scanner.

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Steve G

Posted By: nhoj_yelbom
Date Posted: September 27, 2006 at 12:51 PM

it was 10 leds and a circuitboard to make it scan when 12volts was supplyed, some one gave it to me and the cicuitboard was fried so i wired them up without it. they are bare leds.dualsport how can i make that external current source circuit.

thanks

Posted By: dualsport
Date Posted: September 27, 2006 at 2:31 PM

Did you confirm that your alarm output works with the 5 LEDs in series? From your description of the manual, it seems to indicate it's a constant current output, but you mentioned it didn't work with 5 LEDs, so I'm wondering what kind of output your alarm actually has.
Before rigging up a constant current circuit, you have to know what kind of signal you're using to drive it with.

When the LEDs light up, what voltage do you see at the alarm output? If you hook up the one LED, do you see something in the range of about 2V or something else?
When it's off, do you see 0V at the output or battery voltage?

Posted By: nhoj_yelbom
Date Posted: October 01, 2006 at 8:47 PM

yes, it works with 5 leds in series.

Posted By: nhoj_yelbom
Date Posted: October 01, 2006 at 8:47 PM

and i want them all to flash at the same time. thanks for the help

Posted By: dualsport
Date Posted: October 02, 2006 at 6:53 PM

You can try like this to drive your extra strings of LEDs; depending on how much voltage each one of your extra LEDs need, you may need to break them up into more branches than the two shown here. If they need less than 2V per LED, then you can probably do 2 strings of up to 5. As long as they're in series, they should get the same current, up to the maximum number of LEDs per string.

posted_image

This is assuming your alarm output is normally putting out a positive voltage to turn on the LEDs rather than ground switching- if your current hookup has one end of the LED connected to a constant 12V, then you need to use a different setup.

You can also try regular transistors; the main thing is to get them as matched as possible so that the current is mirrored in the strings of LEDs.

Posted By: dualsport
Date Posted: October 12, 2006 at 12:33 AM

Just a note if someone uses this arrangement; if you use extra bright LEDs that run with higher voltages (Vf), then use a lower number of LEDs in each string, like 3 or 4 instead of 5. Otherwise, the battery voltage when the car is off might be below the level needed, and they won't light up to full brightness.
Just break it up into additional strings by adding another transistor, and you can drive hundreds of LEDs at once if you really felt the need to create a spectacle.

Saw a tractor trailor once that was lit up like Rockefeller Center at Christmas, all covered with LEDs. Not exactly sure what the idea was supposed to be, but it was gone before I could get a better look. posted_image