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relay for 2leds and scanner

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=16334
Printed Date: July 18, 2025 at 6:50 AM


Topic: relay for 2leds and scanner

Posted By: siracer00602
Subject: relay for 2leds and scanner
Date Posted: July 15, 2003 at 1:52 PM

how would i install 2 leds and a scanner with my alarm using a relay? I want them all to blink when the alarm is armed at the same time, but also I want to be able to turn the scanner on and off with a switch.



Replies:

Posted By: siracer00602
Date Posted: July 15, 2003 at 2:03 PM
the scanner has 3 wires:
red-12v
black-ground
blue-alarm trigger

LEDs have only 2 wires just like my old red led that came with my Clifford alarm. Originally the varad led came with a small chip with 3 wires coming from it. I had to snip that off in order to just replace that one red led. Is it possible to use the led i have right now or would i have to buy some new ones with that small chip that makes it blink.




Posted By: xetmes
Date Posted: July 15, 2003 at 2:11 PM

if your alarm output has a flashing signal output (for and LED), just hook the LEDs to that and the scanner trigger to the neg when armed wire (put a switch in series to turn off and on as you describe) . If your alarm doesn't have a flashing LED output, the easiest way would be to just get a flashing LED and wire it with the scanner to the neg when armed.





Posted By: siracer00602
Date Posted: July 15, 2003 at 2:41 PM
yah my alarm has a flashing signal output. That is why i had to cut that chip off. I've tried to hook the 2 leds to it, but then only one of the led's would work. I'm thinking that i would have to use a relay to hook it up or something. This is exactly what i did: I cut off the red led. So there are 2 wires which were connected to the led. I cut off the chip from the flashing blue led. Connected the blue led to the two wires. That works fine just like a regular alarm with one led. I've tried to tap both leds to the 2 wires by just putting 2blacks and 2 reds together and tapping that to the 2 wires that was cut from the original alarm led. That didnt work. Is there a way to like split the signal for the led?..i'm probably doing something wrong anyway. Thanks.




Posted By: Sheldon469
Date Posted: July 19, 2003 at 9:37 PM

Hey siracer00602

Your idea sounds nice, can you post some pics when it's all done!



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Sheldon :)
posted_image




Posted By: Slowper
Date Posted: July 20, 2003 at 5:43 PM
Your LED wire from the Alarm only has enough current to drive 1 LED and wouldn't be able to drive a relay either. The LEDs are typically 2V at 20mA I think this page https://www.the12volt.com/installbay/forum_posts.asp?tid=12465&PN=1 should help you out. Cheers, S.

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Peugeot 206SW Quiksilver




Posted By: xetmes
Date Posted: July 20, 2003 at 8:24 PM
I still say put the scanner on the negative when armed output, and hook a flashing relay to that as well. Otherwise get a general purpose NPN transistor like a 2N3904 and put a 7K Ohm resistor in series with the output to the base of the transistor, wire the emitter to ground and the collector will then flash a negative signal.





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