decreasing the pulse duration

Hi, I have a situation where my aftermarket alarm does not have a wire that is suitable for activating the OEM horn when I set the alarm because it came with a siren (which I don't like and will not be using). Instead, I will rely on the OEM horn for a siren. (This particular alarm has a remote paging function and will notify me up to a considerable distance so the horn is not really necessary IMO, but it will give me an audible confirmation as I walk away from the Van that the alarm has indeed set). Problem is, the one wire I found I can use has a full 1 second pulse duration. So, when I arm the system, the horn blows a bit long for this. Ideally, I would like for the horn to just "tap" (a very short, quick blast of about 1/3 to 1/2 second blast as I arm the system. Is there a way to decrease the duration from 1 second to 1/2 a second (or so) on a wire? thx

Closest thing I've found while Googling.... http://freecircuitdiagram.com/2009/05/20/pulse-width-modulator-using-555-ic/

What alarm system is it...? If it is a 2-way system...You normally get a confirmation chirp on the remote...What do you mean "suitable"...? What kind of car...? The public has become pretty numb to sirens and horns...But i think it is a VERY important part of your alarm...Why not use the siren...? The siren helps for the "not very good thief"... with a siren going off...They will most likely get the heck away from the car...! Almost all aftermarket alarms come with a siren...Most usually come with a horn output too...! If you could give a link for the install manual...? Ill peruse it while im home sick*cough*cough*...M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

Hey Tommy, It's a Carvox king eagle CV- 990 I think. The remote does its thing, I just want the horn to burp once as a louder confirmation. If someone attacks my Caravan, the factory alarm will go off (OEM horn) and I'll be notified via the pager so I'm not quite as concerned about a siren as I would be without the pager...but nonetheless, the Factory horn will be going off. The siren sounds blasee and so run of the mill. It's almost boring. So, rather than hang it somewhere and deal with the wiring, I'm omitting it for the reason above. I got it working, but I used the unsed "arm" wire instead. It works but the horn blows about half a second too long IMO. Intead of a "chirp"...it's a "beeeeeeeeeeeeeeeeep".

Aviator, look to the relay section here for circuits, tommy, wish you better, aviator ref your last post, on certain Chryslers with resistive multiplex wiring, 200milliamps is not enough to overcome the resistance (s) you need e.g. on the locking system. If your unit only has two wires, it means a low current output signal is generated.  If 6 wires, that means on-board relays and you're OK.

Hmmmm ....noone ???? I have a situation where my aftermarket alarm does not have a wire that is suitable for activating the OEM horn when I set the alarm because it came with a siren (which I don't like and will not be using). Instead, I will rely on the OEM horn for a siren. (This particular alarm has a remote paging function and will notify me up to a considerable distance so the horn is not really necessary IMO, but it will give me an audible confirmation as I walk away from the Van that the alarm has indeed set). Problem is, the one wire I found I can use has a full 1 second pulse duration. So, when I arm the system, the horn blows a bit long for this. Ideally, I would like for the horn to just "tap" (a very short, quick blast of about 1/3 to 1/2 second blast as I arm the system. Is there a way to decrease the duration from 1 second to 1/2 a second (or so) on a wire? thx

Are you sure there is no horn output...Just because it came with a siren does not mean there is not a horn output...Is there a link to the install manual...? Is the horn + or -...What is the polarity of the sirens output...? It is usually a positive trigger on the siren...If the horn is negative...Maybe you could use a relay and convert the polarity...Just guessing here...M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

Adding Light Flash with Siren Output

If your alarm has a positive siren output, but no light flash output, the connections are as shown. If you need more info on light flash start here.

Maybe something like this...?M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

Hi Tommy, No, after carefully reviewing each wire and it's purpose, there is no wire that is for attachment to the Factory horn to produce that short armed confirmation beep. The manufacturer assumed that their siren would be used. I used the Carvox's factory ARM wire for the horn and it does sound it but it has a longer than desired duration. Instead of a quick and short little blip of the horn, I get a full 2.5 second blast. A bit too long and annoying, especially late at night when I arm the alarm.