Need help with a timed 12v circuit

Thread Starter

gunguy

Joined Oct 5, 2007
8
I hate to hit you guys with a big one right off the bat, but this is a time sensitive project for work. I am designing a front locker kit for the H2 Hummer. It needs to have a 3 min timed out feature (which I am having a hard time finding from our suppliers) and it needs to use an Eaton momentary switch. the kicker is it needs to triggers from the rear locker circuit but it cannot be wired direct to the circuit or the module faults out for a short to ground. I have been looking for a good program to draw what I need but cannot find that either, any help would be appreciated.
 

ixisuprflyixi

Joined Sep 16, 2007
52
what do you mean by locker? Do you mean door lock? A 3 minute or any minute time delay can be had from a 555 timer very reliably. And as for not being able to wire into the rear circuit directly if you can atleast get 1 component in there you can use an opto-isolator as the trigger, wired to your Eaton momentary of course. A little more detailed description will allow us to help you better.
 

Thread Starter

gunguy

Joined Oct 5, 2007
8
The locker is a locking differancal in the axle. Is the 555 an adjustable timer? do you have a spec sheet and a supplier on it? I am trying to find a program to draw the print up, im doing it on paper with no scanner. Im sure a picture would make things a lot clearer for you. Is an opto-isolator cheap and easy to obtain? do you have a spec sheet and supplier for it also?
 

ixisuprflyixi

Joined Sep 16, 2007
52
the 555 timer is a well known and (adjustable) timer, you must choose the support components based on the delay wanted. The 555 timer is ubiquitous just look up 555 timer on your favorite search engine. The opto-isolator is cheap, so is the 555 but you may be able to get samples for free from fairchild semiconductor, here is a link to a opto-isolator.
http://en.wikipedia.org/wiki/Opto-isolator that page will tell you what an opto-isolator does. and this page http://www.fairchildsemi.com/ds/FO/FOD617D.pdf will tell you about that particular optocoupler (another name for opto-isolator) hope this helps
 

Thread Starter

gunguy

Joined Oct 5, 2007
8
Thanks you have been a great help as soon as I get the schematic where I can post it up I will.
 

Thread Starter

gunguy

Joined Oct 5, 2007
8
Ok I have done a little checking on the timer and the opto-isolator and don't think they would be good options im looking for something that can be wired in by idiots in a self contained box. the timing does not have to be very accurate + or - 10 seconds is acceptable. Do you know of somthing like that?
 

Thread Starter

gunguy

Joined Oct 5, 2007
8
I made up a quick pic with the componets in it. If anyone wants to connect the dots. the input must come from the transfer case control module but it cannot be wired direct to a relay becouse the module will set a falt code.
 

bloguetronica

Joined Apr 27, 2007
1,359
Not familiar with the symbology. What represents those "--))--" like symbols?
I guess I will leave it to who knows about automotive electricity...

P.S.: I have some difficulty circuits that use american symbology, with is a bit (to say the least) different from the european one.
 

JoeJester

Joined Apr 26, 2005
4,074
Those look like "automotive speak" for connectors, could be a molex type connector.
 

Thread Starter

gunguy

Joined Oct 5, 2007
8
Ok I have a different help request that better suits you guys. Could you give me a list of componets that are compatable with 12V automotive wiring, that can receive a 12v signal and start a 3 min timer capable of turning on a automotive 20 amp relay. Im looking for the part numbers of the board, Optocoupler, timer and any parts needed to make it time out in 3 min. This could be a business opratunity for someone if intrested in a small quantiy build
 

SgtWookie

Joined Jul 17, 2007
22,201
It would help a lot to have more of your requirements.

How much current does the 20 amp relay require to engage, and what's the holding current - or what's the part number of the relay?

Will your device be installed in the engine compartment? Conditions can be pretty severe in there; you'd need at minimum industrial-temp rated parts; and they should be in a water/oil resistant enclosure.

There are myriad 12v time delay relays available; they're not cheap, but your target market is an affluent one. However, your competition will notice, and will come out with something similar in a less expensive version.

It would help a GREAT deal to have a schematic of what you have now, and what you need to do.

You could even use Microsoft Paint to create a bitmap image for us to look at. Or you could do a search for "Circuitmaker Student" (freeware; no longer supported) or "Eagle Layout Editor" (unregistered version has good useability for small projects, large parts library, but a bit quirky interface)
 

Thread Starter

gunguy

Joined Oct 5, 2007
8
The relays we will be using should be between 150 and 200ma. The unit will be inside of the truck.
 

thingmaker3

Joined May 16, 2005
5,073
Try using a 555 monostable (in Van Roon's tutorial) to control a MOSFET, which in turn will control your relay.
 

ixisuprflyixi

Joined Sep 16, 2007
52
is this schematic the factory schematic of how the vehicle is supposed to be wired or is this how you think it should be set up? If you want a prototype of this made up it does not seem too difficult.
 
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