Electronics question...

[450Nick]

I'm in the process of designing a circuit to control the ignition on my car and am currently struggling with one part...

I'm actuating the circuit with a push to make (non latching) type switch for a couple of reasons, but the main part of the circuit requires a latching function to drive the main ignition relay. What I really need is for a device or simple circuit to take a 12v pulse from the button, and switch its output from 0v to 12v using a dedicated 12v input, then back again when pulsed for a second time sort of like a flip flop relay.

I'm aware that this can be done with a microcontroller, but it it possible to do with an off the shelf part? My central locking is controlled by a similar relay, which flips its state each time one of the pins is earthed, I'm thinking something similar would be perfect! Any ideas?

[10 Pence Short]

You're always gonna have problems lifting a body in one piece. Apparently the best thing to do is cut up a corpse into six pieces and pile it all together. And when you got your six pieces, you gotta get rid of them, because it's no good leaving it in the deep freeze for your mum to discover, now is it? Then I hear the best thing to do is feed them to pigs. You got to starve the pigs for a few days, then the sight of a chopped-up body will look like curry to a pisshead. You gotta shave the heads of your victims, and pull the teeth out for the sake of the piggies' digestion. You could do this afterwards, of course, but you don't want to go sievin' through pig st, now do you? They will go through bone like butter. You need at least sixteen pigs to finish the job in one sitting, so be wary of any man who keeps a pig farm. They will go through a body that weighs 200 pounds in about eight minutes. That means that a single pig can consume two pounds of uncooked flesh every minute. Hence the expression, "as greedy as a pig".

HTH.

[motco]

That will be a pig of a job to make it latch though...

[rumpelstiltskin]

I wish i could just come on a forum and just straight off answer a question like this,i feel dizzy just reading it!

[450Nick]

No reason really... I just decided to do a bit of a tidy up of my wiring loom this week after making changes over the last year so have pulled the dashboard off, relocated the battery and fusebox and am starting to go about implementing a new dashboard layout I've been designing. As part of it, I'm using some rather fancy new switchgear with dual colour illumination which I'll be using for lighting the dash at night in one colour, and identifying whether or not the button is active (other colour). Already have a start button, so I'm removing the ignition barrel and going to control ignition off a push button, which is rendered active by de-immobilising the car (auto re-arm in 30 seconds if ign isn't started). No other reason than I've got time on my hands and it will look cool

I know its not too hard to make this relay flip flop... I just don't know the relevant electronics and I can't be arsed to make up a pic controller to do it. Someone must know though!

[_rubinho_]

Bistable multivibrator (oooer) driving a relay or some power transistors? Perfect if you just want a steady time period.

[reg_slr]

Take a look at the Maplin website, otherwise just build your own relay logic device depending on the current you need?

[450Nick]

Hmm had a look on the Maplin website and couldn't really find anything that looked right... It only needs to drive a very low current as it will only be providing power to latch two relays. Looks like I might have to dig out the picaxe software

Thanks for the hero comment! I'm not much far past the taking things apart stage, I just kept taking them apart until I remember roughly how they went back together!

[450Nick]

You can do a hell of a lot with them... I've only really scratched the surface making some small programs to control circuits but they can do all sorts. Best thing to do is to download the software and go through the very well written tutorial guides which can get you up to a reasonable standard. You can do things like I'm asking here very easily.. But you do have to take a little time to write the code, then you need to get the programming kit (about £40 IIRC) to write the chips with. I used to borrow a friends board but he's moved away so I'd have to get my own one in this case.

For making little smart circuits though they are pretty good fun and can be used for all sorts of things (e.g making a push button start sequence for your car etc.)

[Zad]

Something like this?



(Replace 1 LED with a relay and protection diode)

Or this method if you want to use a relay:

[eliot]

Zad said:

Something like this?



(Replace 1 LED with a relay and protection diode)

Or this method if you want to use a relay:

uses two switches, OP only has one switch.

[RichyJ]

Found something that might be what you need, but it's on a US site:

http://www.alliedelec.com/Search/ProductDetail.asp...

[eliot]

RichyJ said:

Found something that might be what you need, but it's on a US site:

http://www.alliedelec.com/Search/ProductDetail.asp...

A good find and a little further googling found this uk supplier:
http://www.relays-r-us.co.uk/webpages/products/msd...

[Flibble]

You could just use a T flip flop (with transistor driver)...