how to shorten negative pulse to horn?

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=115302
Printed Date: May 09, 2025 at 11:17 AM

Topic: how to shorten negative pulse to horn?

Posted By: hang122660
Subject: how to shorten negative pulse to horn?
Date Posted: July 26, 2009 at 8:05 PM

I have hooked the negative door lock and unlock wires of my alarm to the negative wire from the horn button. I would like to shorten this pulse to about 1/2 second from about 2 seconds. Two seconds is to long to honk the horn.

And should I add any diodes to this setup?

Replies:

Posted By: hang122660
Date Posted: July 26, 2009 at 8:17 PM

Forgot to add.

I do not have power door locks. The door lock/unlock pulse is only being used to sound the car horn.

Posted By: yimke
Date Posted: July 26, 2009 at 8:22 PM

Don't you have a horn output wire?

Posted By: KarTuneMan
Date Posted: July 26, 2009 at 9:12 PM

PLEASE..... try one more time?

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Posted By: hang122660
Date Posted: July 27, 2009 at 1:40 PM

Don't you have a horn output wire?

No, that is why I have it hooked up this way. The alarm system I got is what I guess you would call a passive system.

It is a Bulldog KE150 I got at Goodwill for $10.00.

Posted By: Chris Luongo
Date Posted: July 28, 2009 at 9:21 AM

I've never used one before, but search for the PAC TR-7.

It's a little timer module with all kinds of cool inputs and outputs and timing adjustments......but I'm not sure if it has a timing selection short enough for your needs.

Just to give you an idea, the Audiovox remote starters I use have a selection for the horn timing, and I think the options are:

10ms, 16ms, 30ms, 40ms, 50ms.

The 16 (default) makes the same kind of honking like most factory keyless systems. The 10 is so quiet you can't hear it very well on a busy street. The 50 isn't objectionable, but is a little too loud for my tastes.

So at least there you have some idea of what kind of timing you need.

Posted By: OmarR
Date Posted: July 28, 2009 at 8:21 PM

Along with Chris' suggestion, another popular one is the DEI 528t.

The input can be a neg or positive pulse, and the output can be anywhere between 1-90 seconds. In reality, if you turn the potentiometer all the way to it's lowest setting, i think you can output like .5 seconds.

They usually average $15 on ebay.