Adding LEDs to alarm output

Home / the12volt's Install Bay / Car Security and Convenience / Adding LEDs to alarm output (

Topic Closed)

Welcome Guest :)

Members

< Prev Page Next Page > < Prev Topic Next Topic >

vibe03

Member - Posts: 27

Joined: December 12, 2005

Location: United States

Posted: December 17, 2005 at 7:22 PM / IP Logged

Dualsport what program did you use to draw that schematic?

art

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: December 17, 2005 at 9:30 PM / IP Logged

That's using Orcad Capture- makes things really easy to draw up.

l0gik2

Member - Posts: 33

Joined: November 14, 2005

Posted: January 08, 2006 at 4:25 PM / IP Logged

I have a python 1500 esp I need to add leds to it. The manual doesn't specify the voltage output for the status led. I put it on my multimeter and it registered about 2v. I'm assuming this is correct unless someone says it should be 12v. The leds i'm putting on are 3.5v. I plan on using the red 2v led and 2 of my blue 3.5 v leds in a series with no resistors. What do you think? I don't care about burning up leds I just don't want to burn up part of the alarm. The leds are 6k mcd so even at 2 volts it will be really bright. I was going to hook it up n test it out, but thought I would ask here first.

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: January 08, 2006 at 4:40 PM / IP Logged

If the alarm's only putting out 2V, it's probably not going to light up when you have those three LEDs in series, not enough voltage to drive them that way.

Might have a chance if you put them in parallel, though the blue LEDs may still be pretty dim, if they have a forward voltage of 3.5V.

l0gik2

Member - Posts: 33

Joined: November 14, 2005

Posted: January 09, 2006 at 12:37 AM / IP Logged

I don't know if I completely trust my multimeter but it goes from 0 to 2 v pulsing with the led. Does that seem odd or normal? I already tried to connect the led in parallel with the stock 2v led and it didn't work at all. Do u think I just need to get some 12v leds and do one of the wiring diagrams listed previously in this post?

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: January 09, 2006 at 1:08 AM / IP Logged

Your DMM probably doesn't update fast enough to give a good reading when it's pulsing rather than on steady, but it sounds like the alarm has the limiting resistor built into the unit. If that's the case, you'd probably need to make up your own circuit to drive more LEDs.

If you have a diode and a cap, you can try using that with your DMM to get a better idea of the open circuit peak voltage being put out from the alarm's LED drive. If it's at least 3V, you can use it to control a BS170 transistor to drive the extra LEDs.

l0gik2

Member - Posts: 33

Joined: November 14, 2005

Posted: January 09, 2006 at 11:45 PM / IP Logged

I don't have a diode or cap on hand is it safe to assume it is probably around 3v? I am unable to find any other information about the power output. I would assume all DEI alarms are prettty similar right? I am going to wire 3 leds in a series and connect them to see if it will drive the 3 leds. Voltage shouldn't be an issue if its at or near the leds forward voltage right? I think it would be more about amps drawn or rather mA. Each led pulling about 20mA.

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: January 10, 2006 at 10:25 AM / IP Logged

Won't hurt to give it a try, but I don't think it'll light up.

You have to have enough voltage to push the current through the diodes, and if you have three in series, you need to add up all the forward voltages of the LEDs for the required drive voltage.

l0gik2

Member - Posts: 33

Joined: November 14, 2005

Posted: January 10, 2006 at 2:06 PM / IP Logged

I want to do 4 or 5. 1 on each door, 1 in each headlight and one in the console. But I don't care as much about the one in the console. To do that I would have to use a relay or something right to get more power to them? Can someone draw me up a diagram for wiring it? I just don't know where to get a 3.5 v power supply from or I could just use 12v and use resistors to all of the leds.

BTW thx for all the help, I am gonig to hook up 3 leds later today and see how well it works if at all. bobk, where did you find that information? I could use resources like that.

KPierson

Platinum - Posts: 3,527

This member consistently provides reliable information

Joined: April 14, 2005

Location: Ohio, United States

Posted: January 10, 2006 at 2:43 PM / IP Logged

Use a transistor, a 2n3906 should work great.

Wire the switching (-) LED output of the alarm though a 220 ohm resistor to the base of the transistor. Wire the emitter to 12vdc and then connect the collector through a 470 ohm resistor to the + side of your LEDs. You can hook them all in parallel, and then hook all their grounds to ground.

Kevin Pierson

< Prev Page Next Page >

Printable version

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum

Search the12volt.com

Follow the12volt.com

Disclaimer: *All information on this site ( the12volt.com ) is provided "as is" without any warranty of any kind, either expressed or implied, including but not limited to fitness for a particular use. Any user assumes the entire risk as to the accuracy and use of this information. Please verify all wire colors and diagrams before applying any information.