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Need a 5 sec. time delay off


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tom badger 
Member - Posts: 48
Member spacespace
Joined: January 09, 2006
Location: United States
Posted: February 16, 2006 at 12:43 AM / IP Logged  
Guys,
I have a circuit that is going through the normally open contacts (terminals 30 & 87) of a relay. These wires feed an engine idle-up control. I'm controlling the coil of the relay with the lock button on my FOB. My FOB has a 3 second pulse. The circuit works great to idle-up the engine (I sometimes have to push lock twice to increase the idle speed as much as I want).
Now, I want to build this into an automatic system - in other words, I don't want to have to push the lock button on the FOB manually to idle-up the engine (although this will also remain functional).   
I want to build a circuit that has a constant input (it's a 12V+ input fed from the alternator when engine starts and runs), with a 5 second output. I want the relay to become energized as it currently is (when the engine starts), then turn off after 5 seconds.
Can someone please send me a diagram for building a 5 second time delay off relay? I'm unsure of the correct size/value of capacitor and resistor to use to get the 5 seconds of on time delay off that I desire.
Thanks!
The Badger
tom badger 
Member - Posts: 48
Member spacespace
Joined: January 09, 2006
Location: United States
Posted: February 16, 2006 at 1:30 PM / IP Logged  
Can someone please send me a diagram (or direct me to a website) for building a 5 second time delay off relay?
I'm unsure of the correct size/value of capacitor and resistor to use to get the 5 seconds of on time
(delay off) that I desire from the relay.
In other words, I simply want to build a relay with a constant or switched 12V+ input, but only 5 seconds of output. The relay becomes energized, then opens after 5 seconds.
Help appreciated.
The Badger
Chris Luongo 
Platinum - Posts: 3,746
Platinum spaceThis member consistently provides reliable informationspace
Joined: May 21, 2002
Location: Massachusetts, United States
Posted: February 16, 2006 at 2:19 PM / IP Logged  
You can buy one already made.
PAC TR-7, or DEI also makes one, but I can't remember the number.
tom badger 
Member - Posts: 48
Member spacespace
Joined: January 09, 2006
Location: United States
Posted: February 16, 2006 at 3:22 PM / IP Logged  
I did a search for the DEI unit,
Does 528T sound right?
Looks like a very versatile unit.
Thanks for the info.
The Badger
Velocity Motors 
Moderator - Posts: 12,488
Moderator spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Fabrication. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spaceThis member has been recognized as an authority in Mobile Security and Convenience. Click here for more info.spacespace
Joined: March 08, 2002
Location: Manitoba, Canada
Posted: February 16, 2006 at 6:14 PM / IP Logged  
The PAC TR-7 is a programming nightmare !! I hate those things !!
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
dualsport 
Silver - Posts: 983
Silver spacespace
Joined: September 27, 2005
Location: United States
Posted: February 17, 2006 at 10:37 AM / IP Logged  
Pretty easy to make one up, use a BS170 MOSFET to drive the relay coil, with an inline cap to drive the transistor high briefly. Then a pulldown resistor attached from the gate to ground turns it off after your time delay. I'll draw it up later and post it-
Here is is-
Need a 5 sec. time delay off -- posted image.
Just use a bigger cap or resistor to get a larger on time, and vice versa.
This assumes your (+) trigger input is at least 5 seconds; if you want it to output the same pulse even with a short trigger, then the circuit would need some mods. Since you said it would be constant, I figure it won't be a problem.
It won't turn on again until the input goes to ground, and then goes back up; then the relay should kick in for another time period.
Send me a postage stamp if you need a transistor-
Need a 5 sec. time delay off -- posted image.
bravesirrobbin 
Member - Posts: 7
Member spacespace
Joined: February 12, 2006
Location: United States
Posted: February 17, 2006 at 11:07 AM / IP Logged  

I recommended this in another thread.  I use these boards for home automation purposes, but it think it would also work out well in your case.

http://www.elkproducts.com/products/elk-960.htm

BTW:  If this helps you out can you take a gander at my thread (call for help?).

https://www.the12volt.com/installbay/forum_posts.asp?tid=72690&PN=1

Thanks

dualsport 
Silver - Posts: 983
Silver spacespace
Joined: September 27, 2005
Location: United States
Posted: February 17, 2006 at 1:05 PM / IP Logged  
That board looks pretty useful, how much does it go for? Seems like a lot of infrastructure for this purpose though-
Seems like the edit feature comes and goes on this board- if you use a polarized cap, the polarity should be switched as in this updated diagram-
Need a 5 sec. time delay off -- posted image.
bravesirrobbin 
Member - Posts: 7
Member spacespace
Joined: February 12, 2006
Location: United States
Posted: February 17, 2006 at 1:39 PM / IP Logged  

I agree, it is a lot more than what is required.  But it is a very handy board, only need one millisecond pulse width to trigger, and has an on-board relay which can be usefull as well.

It is $32 (including shipping) from Automated Outlet:

http://automatedoutlet.com/product.php?productid=541&cat=0&page=1

tom badger 
Member - Posts: 48
Member spacespace
Joined: January 09, 2006
Location: United States
Posted: March 09, 2006 at 10:02 AM / IP Logged  
Guys,
Thanks for the ideas and options.
After doing some testing, I've found that I need a 3 second output (instead of 5 seconds).
So, dualsport, what components/values, etc., do I need to change or modify in the above (updated) diagram to get a pulsed ouput to hold the coil of the relay between 2.75 minimum & 3 seconds max?
(Also, bravesirrobin, thanks for the info on the ELK-960).
Thanks!
The Badger
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