555-based automotive turbo timer

[indecided]

Hi guys..

Was browing through silliconchip and got wind of apparently how easy it is to build a turbo timer.

Anyways, the circut seems to be based about a 555 operating in one-shot mode, trigger would likely be the zero pulse present from the tachometer wire.. Correct me if i'm wrong, i'm just speculating.

just FYI a turbo timer is supposed to be there to "take over" after you have driven and turned the car off to leave it to cool down the turbo bearings so that the oil doesnt' cake up and choke the turbo.

Anyways.. I was planning on a very non-descript one. NO fancy timer display, just a few preset values.. say 30 and 60 seconds of running. Just want to be able to chuck a black box under the dash with no prying hands to play with it.

But if it's not too hard to implement a timer display, I supposed it'll need another IC to control it, it would be a good idea.

Here's a rough look at the interior of a simple turbo timer, slectable at 1/3 minutes. frankly, it doesn't look like much work. Don't bother reading.. the site's in Japanese.
http://www.yagisawa.net/noah/pw_window/index.html

Anyways, to recap.. where do I start with for a trigger input? It's supposed to detect the moment the car switches off and takes over immediately.

 

[Roff]

Well, I have to admit I haven't kept up with turbocharger technology, but a little Googling convinced me that they are still exhaust-driven. How do you electrically spin a turbocharger? Or am I way out of date?

 

[TheOne]

I think he want the enjin to keep on idling for a certain time before switching off, after he left his car.

 

[indecided]

yep, Ron.. they are exhaust driven.

But this has nothing to do with the workings of the turbocharger.

Just how to keep the car idling by itself for a preset period of time, then switch off.

 

[Roff]

yep, Ron.. they are exhaust driven.

But this has nothing to do with the workings of the turbocharger.

Just how to keep the car idling by itself for a preset period of time, then switch off.

Duhhh... I get it.

 

[magickaldan]

Hi guys..

Was browing through silliconchip and got wind of apparently how easy it is to build a turbo timer.

Anyways, the circut seems to be based about a 555 operating in one-shot mode, trigger would likely be the zero pulse present from the tachometer wire.. Correct me if i'm wrong, i'm just speculating.

just FYI a turbo timer is supposed to be there to "take over" after you have driven and turned the car off to leave it to cool down the turbo bearings so that the oil doesnt' cake up and choke the turbo.

Anyways.. I was planning on a very non-descript one. NO fancy timer display, just a few preset values.. say 30 and 60 seconds of running. Just want to be able to chuck a black box under the dash with no prying hands to play with it.

But if it's not too hard to implement a timer display, I supposed it'll need another IC to control it, it would be a good idea.

Here's a rough look at the interior of a simple turbo timer, slectable at 1/3 minutes. frankly, it doesn't look like much work. Don't bother reading.. the site's in Japanese.
http://www.yagisawa.net/noah/pw_window/index.html

Anyways, to recap.. where do I start with for a trigger input? It's supposed to detect the moment the car switches off and takes over immediately.

Well here's what I would do but it only applys to cars that don't have the security chip (resistor) on the ignition key. For those you will have to buy a Remote start circuit addon to make them run without the key. Anyways basically all you have to do is keep the Ignition switch wires in the closed position while the actual switch is in open position. For this you could use a simple timer circuit. and tie it into the ignition wires so that one you turn the key on it activates. and when you flip the key off it stays active for a certain time, maybe use a capacitor to time. I'll add a circuit of a timer if you need it. But remember this only applys to the cars without the security resistor on the key. But if your car has one of those then you'll have to buy the addon for Remote Start systems, last time I checked around here in kansas they cost around 30 dollars US (my firebird would need one if I ever added a remote start that's why I know).
I know this because it works the same as a remote start which my old thunderbird had, and I took off to put on a Mazda protegea. It basically kept the wires that run to the ignition switch in a closed position until the key was put in to take over and allow you to drive. But this should work on the same principal.

Sorry for the lengthy post I wrote untill I felt it nescesarry to stop.


EDIT:: I added this diagram to make it more understandable. Now this is for most cars but not all cars may be like this.

 

[FRIED]

2 cents
**broken link removed**

 

[indecided]

2 cents
**broken link removed**

FRIED, thanks for the excellent link to a simple circut.

Now to work out how to bypass the alarm starter cut.. As you should know the alarm will not allow the car to be locked as long as there the engine is still running..

 

[indecided]

just figuring stuff out from the diagram..

A1 is the reset switch?

why is the reset pin tied to V+?

I'm not too sure how the rest of the circut works, could someone explain it? thanks!

 

[indecided]

oh yeah..and also what parts n values would be suited for this operation?

 

[Oznog]

A 555 cannot be made to time very reliably over long periods. It's not a flaw in the 555 itself. Leakage on the large cap at temp extremes, leakage from board moisture, etc can make fail to trigger in the designed time or maybe fail to trigger at all. A 555 run at moderate time periods feeding a counter is a better solution.

Better yet, a microcontroller can do a better job still. If you have other requirements like tricking the alarm system, its capabilities would prove invaluable.

 

[indecided]

A 555 cannot be made to time very reliably over long periods. It's not a flaw in the 555 itself. Leakage on the large cap at temp extremes, leakage from board moisture, etc can make fail to trigger in the designed time or maybe fail to trigger at all. A 555 run at moderate time periods feeding a counter is a better solution.

Better yet, a microcontroller can do a better job still. If you have other requirements like tricking the alarm system, its capabilities would prove invaluable.

I would say it's workload would be 30 seconds x 3 times per day. I don't think that would be a prob? Considering that the unit would be in the car itself and not the car bay.. heat shouldn't be a problem either.

Anyways many of the turbo timers in the market today are based upon the 555 with a couple more additional chips for counter display, etc...

 

[bryan1]

Hiya indecided,
In taking a quick google I came up with this link
**broken link removed**
although it uses a pic to do the work it's one of the best ideas Ive seen for a do ya own turbo timer aswell a heap of other features

Cheers Bryan1

 

[dhuDz]

Hiya indecided,
In taking a quick google I came up with this link
**broken link removed**
although it uses a pic to do the work it's one of the best ideas Ive seen for a do ya own turbo timer aswell a heap of other features

Cheers Bryan1

hi bryan, the site is not working