1 sec pulse to 4 sec pulse

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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=94671
Printed Date: May 05, 2025 at 8:05 AM

Topic: 1 sec pulse to 4 sec pulse

Posted By: craigpiper
Subject: 1 sec pulse to 4 sec pulse
Date Posted: June 10, 2007 at 11:54 AM

hi everyone,

I live in the UK and i have just visited my local electronic componates shop and they have tried helping me as much as possible, but i am still stuck!

What i am after is something i can give a 1 second supply of 12 volts and that then turns into 3-4 seconds of 12 volts!

what i am trying to do is take power from my door actuater and give it to my powered wing mirrors, so that when i lock the car the mirrors pull in and unlock, they go out

at the moment if i take feeds from the door motor and put them on the mirrors, the mirrors only move for 1 second and it needs to be 3 seconds.

i have looked at using relays circuts that clever people have put on here but they are over complicated for what i need.

sorry for typing loads but this is really bugging me and i am sure that you guys in the USA will have some ideas as you seam to have a lot more gadgets etc than we do here in the UK.

there must be something i can give a constant 12 volts and trigger it with a 1 second paulse of 12 volts to give me a changable timed output???

please help as i am in desperate need of your knowlage!!!!

thanks

Replies:

Posted By: Big Dog
Date Posted: June 11, 2007 at 10:47 AM

A circuit like the following will work. A larger cap or a larger resistor will increase the time and inversely, reducing the cap or resistor will shorten the pulse.

posted_image

Another idea, even simpler. You need two things: a relay and a 470 mfd /16vdc polarized cap. Put the cap in parallel with a relay`s coil. This should give about three seconds. Increase cap for increased time. Timing won`t be nuclear precision but good enough for your purpose.

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Prepare your future. It wasn't the lack of stones that killed the stone age.

Posted By: dualsport
Date Posted: June 12, 2007 at 10:47 PM

Sounds like you'll want to buy a commercial unit, there's a previous post on it here

Posted By: hotwaterwizard
Date Posted: June 14, 2007 at 8:41 AM

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: craigpiper
Date Posted: June 14, 2007 at 7:11 PM

i know i am new to the world of electronics, but am i right in saying that a capacitor stores power? if so, is it not possible to put the cap on the output of the relay to reliese the power???

Posted By: dualsport
Date Posted: June 23, 2007 at 11:18 PM

It does store energy, but you'll need one of the circuits shown above to do the job, because a real world cap won't store enough to operate your power mirrors for three seconds after being charged up for only a second. The relay is needed to actually provide the power, and the capacitor is used only for timing control of the relay or transistor drive.
If building something sounds too complicated, then you can just buy a ready made item to do what you want.

Posted By: craigpiper
Date Posted: June 24, 2007 at 7:23 AM

where can i find somthing that will do this all ready made? do you know of any online sites that i can look at it?

Posted By: dualsport
Date Posted: June 24, 2007 at 7:35 AM

It didn't sound like you wanted to build it yourself, that's why I suggested this earlier.
click on this

Posted By: craigpiper
Date Posted: June 24, 2007 at 7:42 AM

since putting up this post i brought a double paulse locking relay for the people i buy my alarms from, and this worked perfectly, but the only trouble is that they only had one from old stock and are not getting anymore and i need about 30 kits