12 volt timer relay wanted

MrT · Posted: Sun Jun 06, 2004 9:50 am Post subject: 12 volt timer relay wanted

I used to have one of these devices as an add on for my car some 25 years ago! It fitted in with the courtesy light and turned it off after about 10 minutes. There are some modern electronic equivalents but they are designed for about 5W when I probably need 2-3A for all the GPS and associated equipment.

I now want one of these for my in car GPS gear. The idea being when I stop for a few minutes everything remains powered but after a certain amount of time it turns off to save the battery. At the moment I have the choice of permanent wiring it and flattening the battery or having it wired through the ignition where it turns off every time I stop for petrol, turn off the engine in a traffic jam etc.

I have looked at the usual Maplin/RS/Farnell and seen nothing obvious.

lbendlin · Posted: Sun Jun 06, 2004 5:07 pm Post subject:

Another option would be for the navigation program developers to finally support the suspend/wakeup signals that he OS sends. Like, save program state on suspend, restore on wakeup. So far only TomTom seems to do this properly. Most others crash on wakeup, either irregularly (like Mapopolis) or reproducibly (PaPaGO)
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nickwaring · Occasional Visitor Joined: Oct 20, 2003 Posts: 12

Hi,

I too was looking for a piece of kit that would do this but couldn't find one.... so I decided to embark on a bit of amature electronics!

The result is a small circuit that takes a feed from the ignition controlled 12v and the constant 12v and provides a power off delay of about 6-8 minutes from the time the ingition is switched off.

Admittidly I can't take all the credit.. I found a link through google to a site describing the circuit... (http://www.astron.nl/~smirnov/poweroff.html) but it's aimed at someone with knowledge of circuit building so it did take me a few days of fiddling ( and some replacement components!) to get it working properly.

It's really cheap to make as the components only cost under £10 (although it did cost about £40+ by the time I'd bought all the equipment required - a decent soldering iron, glue gun etc..). That said I did enjoy the challenge so I didn't mind too much! (And it works it really well)

PM me if you want more info

Nick

MrT · Posted: Tue Jun 08, 2004 4:07 pm Post subject:

Thanks, I hoped to be able to buy a prebuilt in a nice box model, but this is the sort of thing I was looking at. If I cannot get one, I suppose I will have to build it.

nickwaring · Occasional Visitor Joined: Oct 20, 2003 Posts: 12

Happily build one for you...

Torchy · Posted: Wed Jun 09, 2004 9:18 pm Post subject:

One school of thought is to try Maplins. However the answer is simple. You say that you can obtain a timer that is capable of switching 5 watts. Well this can be used to switch a relay with heavier contacts. If you need the circuit then please send me an email.
Dave

philip4242 · Regular Visitor Joined: May 26, 2004 Posts: 123

The answer may be even simpler (and cheaper !)

I have one of these in-line with my GPS, to keep the 'mouse' permanently powered, without fear of it flattening the car battery (after many days, admittedly !)

I don't know how they can sell them at this price ! (currently £4.49, until 07/08/2004), although I'm sure the non-special offer price ought to be either £6.99 or £9.99 - and definitely not £69.99 !!

http://www.maplin.co.uk/products/module.asp?CartID=04080122280651&moduleno=37962
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Getting older and more senile by the minute !

Philip

Hunnymonster · Posted: Thu Aug 05, 2004 9:16 pm Post subject:

Just the job! Been looking for something like this for ages - for the electric coolbox! Original price (in store at least) was £8.99 - so I'll leave it as an exercise for the interested reader to figure out where the £69.99 came from Laughing

dlegros · Occasional Visitor Joined: Aug 03, 2004 Posts: 30

I've installed one of these for my TT setup, I got the idea from our Campingaz electric coolbox which has this circuitry built in.

It's a lovely neat little unit. Hides nicely out of the way.

Dom

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