12v timed relay needed
Printed From: the12volt.com
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=111646
Printed Date: May 14, 2024 at 12:59 PM
Topic: 12v timed relay needed
Posted By: djeuroalex
Subject: 12v timed relay needed
Date Posted: February 16, 2009 at 3:46 PM
I have 2002 Vw Jetta and what I’m trying to do is put a timed relay to turn of my driving lights after about 30 sec. ignition was turned of. So I’m means it has to pass current when the ignition is turned on or cycled and remain turned on for 30 sec? Any help would be appreciated. Thanks Guys!
Replies:
Posted By: djeuroalex
Date Posted: February 16, 2009 at 3:49 PM
I have 2002 Vw Jetta and what I’m trying to do is put a timed relay to turn off my driving lights after about 30 sec. ignition was turned of and the switch remained on. Like stock 2003 Acura TL has. So I’m means it has to pass current when the ignition is turned on or cycled and remain turned on for 30 sec? Any help would be appreciated. Thanks Guys!
Posted By: hotwaterwizard
Date Posted: February 20, 2009 at 8:21 AM
What you are looking for is an off delay. 
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: djeuroalex
Date Posted: February 20, 2009 at 10:34 AM
hotwaterwizard Thank you !!!!!!
Posted By: hotwaterwizard
Date Posted: February 20, 2009 at 6:51 PM
Please let me know how it works, I designed it myself
-------------
John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: djeuroalex
Date Posted: February 22, 2009 at 11:25 AM
Yes I will post as soon as I have results, also what components can i add and where so the timer resets it self when the circuit is broken but not when it just came in contact this is for door trigger so when you open (break circuit) it will reset but when you close it wont. hotwaterwizard Thanks! I wish I had knowledge like you do.
Posted By: hotwaterwizard
Date Posted: February 22, 2009 at 5:04 PM
Which Diagram are you going to use? ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: djeuroalex
Date Posted: February 22, 2009 at 10:54 PM
Not sure yet what is the difference between NPN and PNP? what does that stand for?
Posted By: hotwaterwizard
Date Posted: February 22, 2009 at 11:37 PM
https://www.kpsec.freeuk.com/trancirc.htm------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: dualsport
Date Posted: March 14, 2009 at 12:36 PM
Hotwater,
Did you try it with the values of resistors shown? With 43k ohms effectively in series for the base drive, it would be a very low current output from the transistor. The relay would need more drive current to energize.
I usually like using a MOSFET for timing circuits, because they're voltage controlled rather than current controlled, and effectively open circuit inputs, so they don't draw any current from your timing circuits.
That lets you use very small capacitors to get very long delays. I don't know why the 12V reference still shows a huge cap/resistor combination directly driving a relay for delay applications. It's much better to use a transistor driver for it, whether a bipolar or MOSFET.
Posted By: oose
Date Posted: March 18, 2009 at 1:01 PM
Dualsport - would you mind drawing up a schmeatic of that? My electronics is a bit rusty (it's been a while)
Posted By: dualsport
Date Posted: March 18, 2009 at 11:31 PM
This will turn on the relay whenever the ignition is on, and delay the turn off after the ignition is turned off.
You can adjust the turn off interval by changing the capacitance and resistance in the circuit. If you use a potentiometer, you can turn it until you get the time delay you're looking for.
Posted By: oose
Date Posted: March 19, 2009 at 11:02 AM
Thanks Dual -
I think this work perfectly.
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