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A working temperature gauge

Come and see what our Jon is up to, with his electric gizmos that his mind and hands mould into magic little boxes of tricks, he gets bored very easily, so if you have an idea that you can throw at him, all the better for him to play with ;0)
paggers
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Re: A working temperature gauge

Postby paggers » Fri Jun 14, 2013 2:33 pm

Cheers Jon. I did my degree (many years ago) in microelectronics and a large amount of the work covered designing and building embedded microcontroller circuits. I have never used those skills in anger but looking at some of your products (and working out in my head how you probably did it) has sort of re-awakened the desire to build something and my car seems like a fun test bed. I rather regret that my Mk1 doesn't have an OBD port as hooking up to that would be an interesting challenge.

Out of curiosity - and without asking you to give away any trade secrets - are you using a microprocessor or microcontroller chip for your projects and would you be willing to say which one? In my day it was the 68000 microcontroller and the 8086 microprocessor working mostly in assembly (although we did high level languages on the course as well). If I did something now I reckon I would look at one of the Parallax products, probably their propellor chip (we have one of their S2 scribbler robots in the house which has always intrigued me).
Niall


1997 1.8i Roadster in Black
- Induction kit, Stainless Exhaust System, Lowered Springs
1998 1.8i S MX-5 in Silver
- Under restoration

Also into taking a few pictures - check out my website.
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binarypunk
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Re: A working temperature gauge

Postby binarypunk » Fri Jun 14, 2013 2:57 pm

I use Microchip PIC MCU's in all my products. Well, not the fault code reader, obviously... :-)

OBD is certainly interesting, but being generic and extremely popular, the Chinese are producing white-label circuits for OBD devices at a pound or two at a time, and the Torque app can do everything the interface is capable of, so I couldn't see any way to compete or produce anything new.

Lazza: In my eyes, gauges should do two things: a) to let the driver know when there is a problem, and b) to not distract the driver when there isn't. Physical gauges were all that designers could use to solve this until recently, but they have serious flaws - mainly, they don't shout when they need to - but also, waggling needles mean that the driver needs to look, decode the data, and decide if it signifies a problem or not...when really they should be driving.

The oil gauge is a particular problem though - there is useful data to be had from watching how it acts (it could signify a blocked gallery or worn pump if you really know what you're looking at). Unfortunately the vast majority of drivers don't know how to decypher it, and more likely think there is a problem when there isn't (why is it moving around? they ask). BUT....Whether you know what you're looking at or not, all you really need is to know is it 'good' or 'bad'.

My oil light, like the switch-type gauge, only looks to ensure that the pressure is above a safe idle pressure. It of course has the added benefit of being noticeable, but other than that it's quite dumb. I have been toying with the idea of an intelligent light, which would take engine speed into account and ensure that the pressure is changing as it should be. This could warn of such problems, but would introduce another problem that it wouldn't necessarily be obvious what the problem is. Plus the programming will be a nightmare, and I have too many other things to do right now.

The fundamental problem with using a temp gauge as an oil gauge though...is that they work in opposite directions (falling or rising voltages) and in different ranges, so the modding would need to be extensive.
Jon - UK Mk1 1.6 1993 Classic Red

Check out my MX5 mods and tools:
http://www.binarypunk.co.uk
Need spares? Go to Autolink!
http://www.autolinkuk.co.uk/
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Lazza
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Re: A working temperature gauge

Postby Lazza » Fri Jun 14, 2013 3:09 pm

I wasn't expecting my suggestion to be a realistic one :lol:

I already have oil temp, boost pressure and AFR gauges in a 3-gauge din plate so I'm happy enough with what I have. IMO, oil temp is more important than water temp, especially with FI as I want to avoid using mych boost/revs until the oil has got up to temperature. At some point I plan to replace my oil temp gauge with a dual oil temp & pressure gauge. Those gauges are all away from my line-of-sight.
I'll leave the stock gauges/lights as they are.

I believe that what you say about the reason for the flat-spots on the gauges is exactly the reason Mazda did it. They had loads of calls at dealers from buyers saying that there must be something wrong with their engines because the gauge was moving around too much.
Lazza

2001 Mk2.5 MX5 1.8 Sport
Hard Dog Deuce
GAZ Gold Pro
Mk3 seats
17” OZ Racing Superturissmo wheels (for the toad)
15” Rota Circuit 10 wheels (for track use)
paggers
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Re: A working temperature gauge

Postby paggers » Fri Jun 14, 2013 5:02 pm

Good points there Jon - no sense in building something that I can get off the shelf for a couple of quid. But you have got me interested now so I'll have to scratch around and come up with a suitable project to keep me amused.
Niall


1997 1.8i Roadster in Black
- Induction kit, Stainless Exhaust System, Lowered Springs
1998 1.8i S MX-5 in Silver
- Under restoration

Also into taking a few pictures - check out my website.
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binarypunk
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Re: A working temperature gauge

Postby binarypunk » Fri Jun 14, 2013 5:16 pm

There is some scope to produce an OBD interface for the MK1/2's that would be plug and play with the 17pin connector, and output OBD-compliant messages so that you can interface with it using existing OBD readers. I was tempted to produce something similar so that the codes would be displayed on 7-segs and with various switches provided for the test functions.

However, I found that the connector is hard to source (or have made) at anything like a sensible price...it would have made the final product very uncompetitive compared to an LED and wire, and no better featured (just easier to use). Given a volume of a few hundred or more it would be worthwhile, but while a lot of people want something easier to use, they aren't happy spending ÂŁ20+ on it, when they can get an LED for next to nothing, or one of my simple readers for less than a tenner...so that kind of volume is probably unrealistic.
Jon - UK Mk1 1.6 1993 Classic Red

Check out my MX5 mods and tools:
http://www.binarypunk.co.uk
Need spares? Go to Autolink!
http://www.autolinkuk.co.uk/

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