Relay With Delay

[zim]

Morning,

I'm sure i've seen a post about this on here, but i can't find it From memory it was DaveW that wrote how to do it ? *i think*

I'm putting together a reverse camera system which switches on the screen when you engage reverse. But my screen stays live for about 3 or 4 seconds after reverse is unselected.

The oem recomendation system is to put the camera on ignition live so it's 'always ready'. But i don't trust my £10 ebay special to stay on all the time so wish to power it from the reverse signal.

So.... What is the easiest way that i can have the reverse signal switch on a relay and then keep that relay live for say 10 seconds after the switching 12v is stopped.

I'm sure there must be an interior light relay or something that i could use....hmmmm ?

Thanks

Gordon

[Escape]

You can buy a relay with a built-in timer, as is used for glow-plugs and some LPG-systems. You wire it like a normal relay and set the delay.

[simonr]

Do you have a soldering iron? If so, it's dead easy to build such a thing with 1 diode, 1 transistor, 2 resistors, 1 variable resistor & 1 capacitor. I just built such a thing for Nick (RogueVogue) to give variable post gas flow on his TIG welder. Only took 10 mins to build and gives a delay of 2 to 30 sec.

If it's a goer I'll post a circuit!

I'm not entirely clear why you need a delay? Can you not just power the whole thing off the reverse light feed? When you take it out of reverse, it switches off. I can't see what you gain by it staying on for an additional few seconds?

Is it that it takes a few seconds to power up and that if you are shunting (alternating between forwards & reverse), it's not quick enough? If so, you could connect the main unit to ignition live and the LCD back light to the reverse light?

Si

[Cynic-al]

I have a reverse camera linked to my head unit and it drives me crazy. Basically the head unit is set to switch to the reverse camera input when it receives a signal on that line. The camera is wired to the reverse light so it powers up when you stick it in reverse and the head unit switches over.

When its all up and running the time it takes to switch over when you pop it into reverse is acceptable, however i'm guessing you want the timer as if like me you go for forward gear whilst its still rolling backwards you lose the camera.

However what really drives me crazy with mine is the safety warning message you get when you first turn the ignition on, it says something like 'do not allow this screen to destract you whilst driving' for about 10 seconds, in that time i've usually reversed out the spot, run a child over and am half a mile down the road.

The problem with these relays is they usually need a permenant live feed which isn't in your rear cluster so it would need a live cable running. The capacitor circuit above might get around this depending how much power the camera pulls and how quick you can charge the capacitor from the rear light feed.

I'm guessing your thinking of something like this

http://www.polevolt....info_74205.html

And I would wire it like this (which I think works - it is friday!);

So you stick it in reverse, the 5 pin relay switches over connecting the camera to the 12v live feed. Pin 15 of the timer is disconnected from the live feed resetting the timer. You take it out of reverse the 5-pin relay switches back disconnecting the camera from the live feed and triggering the timer. The timer powers the camera through pin 87a (NC) until it switches on after the time limit and turns the camera off. the 5-pin relay stops the live feed going back to the reverse lights.

There might be a blip in the time it takes to switch over and I think you could do a neater job with your own circuit.

Something like this would do it buts its american, you can set it to start timing once the signal is removed which is ideal.

http://www.smarthome.com/77419/Enforcer-Mini-Timer-Module-1-to-60-seconds/p.aspx

[zim]

Do you have a soldering iron? If so, it's dead easy to build such a thing with 1 diode, 1 transistor, 2 resistors, 1 variable resistor & 1 capacitor. I just built such a thing for Nick (RogueVogue) to give variable post gas flow on his TIG welder. Only took 10 mins to build and gives a delay of 2 to 30 sec.

If it's a goer I'll post a circuit!

I'm not entirely clear why you need a delay? Can you not just power the whole thing off the reverse light feed? When you take it out of reverse, it switches off. I can't see what you gain by it staying on for an additional few seconds?

Is it that it takes a few seconds to power up and that if you are shunting (alternating between forwards & reverse), it's not quick enough? If so, you could connect the main unit to ignition live and the LCD back light to the reverse light?

Si

That'd be much appreciated please Si.

My original plan was as you said, have the camera switch on by taking a feed from the reverse lights. It's how i wired it today to test all my wiring.

BUT

The mirror, which is from a Ford F150 looks like a normal mirror - you'd be none the wiser it had a screen. This has a reverse signal feed (as well as 12v and earth for the auto dimming). When you select reverse the camera switches on as well as the screen - giving you rear view - all good so far. But when you engage forwards, for some reason the mirror keeps the camera screen 'live' for about 4 or 5 seconds. However the camera is off, so you get a fuzzy then blue block due to not having a video input.

If the camera could be on that little bit longer then i'd not get this. Call me tart, i just don't want to have it looking like a bodged job

As mentioned in the first post, Ford keep their camera on all the time.

G

P.S. reversing up to the trailer is going to be dead simple now ! Wish i'd done this with the P38. Prior to this i had a bog standard mirror with no electrics - not even dimming.

Edit : What about something like this : http://www.ebay.co.u...=item2c63d28059 how do they work ?

I had a look at RRC courtesy lamp relay today but it had 9 wires coming out of it, so couldn't be bothered to try work them all out

[RangeyRover]

Agricultural railway way, simple and effective. You may want to limit current draw to the fuse rating of the cct.

if 3A then wire a 4 ohm resistor in the supply line 12V/3A = 4 ohm

Capacitor needs to be fairly large to accomodate the low coil resistance on 12V relays

I suspect the older courtesy lamp relays use this so the ebay one is prob suitable.

[gordonendersby]

If anybody else is thinking of getting a reversing camera and screen, they are incredibly cheap now on ebay if you dont mind waiting a couple of weeks for delivery.

Ive just fitted a system to my 110. It has a choice of 4 cameras, rear view mirror screen and it was wireless.

It was just over £60 including delivery. I dont know how that compares to the bits youve got hold of seperately.

The mirror/screen clips surprisingly securely to the rear view mirror and you plug the power supply and receiver in to it.

I had to make a small bracket to fix the camera to the back of the 110 close to the roof to angle it down a bit more.

I cant see the tow ball because the spare wheel is in the way. I may experiment with other positions for the camera.

I wanted it mainly for parking as I kept over compensating when reversing up to smaller cars that disapeared behind the spare wheel. I kept finding Id left about 4 feet space to make sure I didnt nudge them.

The camera is powered from the reversing light and the screen turns on when it gets the signal and turns off immediately when the camera turns off.

Amazing kit for the price.

This one is similar and supposed to be from the UK, Ive got no connection with the suppliers.

http://www.ebay.co.uk/itm/4-3-Wireless-Rear-View-Mirror-Handsfree-Car-Reversing-Kit-Back-Up-Camera-/120882724209?pt=UK_AudioElectronicsVideo_Video_TelevisionSetTopBoxes&hash=item1c252bfd71#ht_10758wt_995

It might be the same kit I got hold off.

How and where have you mounted your camera?

Gordon (not the original poster, but another Gordon)

[zim]

Gordon, this is not on a LR but in answer to your question it's just above my rear bumper and angled so i can just see the tow ball.

Here is a dodgy phone video, you can't see the camera picture due to the glare but it is working. At about 7 or 8 seconds into the video, I take it out of reverse and you see the problem i'm having.

[gordonendersby]

Is the screen designed to have 2 feeds, 1 for the reversing camera and 1 for other info from the original cars systems?

If it is, it might be trying to revert to the other display after the reversing camera and not finding anything, then shutting off?

Is it possible to hook into the other feed if it has it?

Gordon

[zim]

There is only supposed to have one input, the camera is normally live all the time.

Si - any chance of a little diagram please

Thanks

Gordon