I want to have a button in a car that when pressed holds an output at either 12v or ground (to operate a relay) for 20 mins (for example would like it adjustable time ideally)

Anyone know of anything that does this in a neat little enclosed unit?

I know I could build a timer circuit but looking to just buy something if poss to save time.

 

Ps

The start switch needs to be external for subtle mounting not part of the unit, just want a very plain little switch for that not the whole unit on display.

 

Theres a thing on ebay for coming home lights thats kinda what you're looking for. It doesn'y have a switch, but the way it works, you could easily wire a switch into it. Only does 30secs to 2 minutes though.

I can take photos of the inside of one if it helps?

 

monostable multivibrator

 

RS Components sell all sorts of relays that will do this from a push button, not sure how readily available 12v DC equipment is though.

 

Chip. I'll reply to this later. I may have a circuit diagram for a self latching timer relay that I was using to control a solenoid. I'll see if its on my laptop when i get to work

 

As above, rs compontents will sell something that will do the job but it will probably look a bit agricultural for a car as they are mostly din rail mounted. I made a turbo timer out of one a few years back.

 

My Mrs has one of those.

 

Chip,

This is a diagram of a circuit I used to hold back a solenoid for 20 seconds using a self latching idea with an on delay timer to open the feed to both coils. The MY 4 pole relay was there to handle load from the solenoid and to provide the latch (closed circuit) to keep the timer powered and the MY4 relay latched in. After the time limit, the timer would open the contacts and break the circuit.

Using the relay in the link below, you wouldn't need the additional MY4 relay as the timer itself has 4 sets of contacts inside it (but only rated at 5 amp) so it could provide it's own self latch and then you could use one of the other sets of contact to power what ever you need.

http://uk.rs-online.com/web/p/time-d...elays/2361329/

 

Well it made me laugh, and the funny thing was I wasn't lying lol

 

http://polevolt.co.uk/acatalog/info_74205.html

think thats what your looking for,

 

That looks very promising, thanks


And thanks to everyone else for suggestions.

 

In the words of a three year old - Why? (just curious really)

 

Was considering as a timed way to switch maps for a track session that automatically switches back after enough time for the session to be over, to save someone forgetting to switch back.

 

http://autospeed.com.au/cms/A_110692...popularArticle
Just seen this and thought you might like it

 

Doesn't your mate Doug have something similar in his cars?

 

Sounds ideal operationally, just wish it was a little better packaged in a case not just a board.
Thats relatively easy to sort though of course.

 

Yes but for a slightly different purpose

 

that's confusing

 

Lol they are as confused as me lol