Pulsed output

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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=13592
Printed Date: May 31, 2024 at 6:36 PM

Topic: Pulsed output

Posted By: jmyinc
Subject: Pulsed output
Date Posted: May 16, 2003 at 7:17 AM

My friend just bought a new car and the car alarm siren sounds like a chicken quacking when chirping (lock and unlock chirps). What he is wanting is something where he can press one of his option buttons and his car alarm siren pulses about twice per second or so for like 30 seconds, or even if you have to push the button again to turn it off that will be fine. I know this will be alot more than just a relay.

I was thing like an ic chip or something, but thse only operate on like 5 volts.

Thanks

Replies:

Posted By: jmyinc
Date Posted: May 17, 2003 at 7:37 AM

anybody?

Posted By: xetmes
Date Posted: May 18, 2003 at 10:54 AM

hmmm, i dont understand. Do you want it you just chirp each second for 30 seconds then stop or a few times a second or something? If so that wouldent be all that difficult.

Posted By: jmyinc
Date Posted: May 18, 2003 at 7:28 PM

Yes, I want it to chirp a couple times a second for 30 seconds. Maybe a a variable resistor to make it chird slower or faaster.

Posted By: xetmes
Date Posted: May 18, 2003 at 7:54 PM

is the option output a low or a high pulse?

Posted By: jmyinc
Date Posted: May 18, 2003 at 8:04 PM

I do not know, Its on a Prestige alarm, dont know the model.

Posted By: xetmes
Date Posted: May 19, 2003 at 11:57 AM

posted_image

This *should* work in theory. After recieving a signal from the option input, it will pulse the output high for .1 sec, low for .4 seconds and keep doing so for about 30 seconds. The timing intervals can be changed by changing R4 and R5, if you would like a variable rate i would suggest a potentiometer (like a 0-10K) in series with a 100K resistor for R4. Also the value of R1 will determin how long the output keeps pulsing (the higher R1 is the longer). The output i would assume you want to hook to a relay. Remember this will only give you pulsing DC, so if the siren requires an AC driver it wont really work. Also i take no responsibility for this thing if it destroys the alarm and/or car, use this at your will. If you want i can write a description of how the circuit works.

Also, this is not the best or most reliable circuit, but it is the most simple way of doing it i could think of.

Posted By: xetmes
Date Posted: May 19, 2003 at 11:58 AM

oops i ment to say "if you would like a variable rate i would suggest a potentiometer (like a 0-10K) in series with a 1K resistor for R4."

Posted By: xetmes
Date Posted: May 19, 2003 at 1:18 PM

wait i messed up the transistor at the end, in that circuit when the circuit is off, the siren will always sound, not good, here is a better setup, notice it is a negative output though. no problem really, i also put a relay in to show how it would be hooked up. Note that is and NPN transistor at the far left and a PNP in the middle.

posted_image

Posted By: jmyinc
Date Posted: May 19, 2003 at 1:40 PM

Hey thanks man, that helps a lot.

Posted By: xetmes
Date Posted: May 20, 2003 at 5:34 AM

hmmm... for some reason it says 430 ohm for the second diagram (R1), that should be 430 K Ohm (like in the first diagram)