Digital Tach

[Lachlan]

I am an advocate of simplicity and would prob not go so far as a PLC or other programable
device. Apart from the fact that I only ever did it at TAFE in Aus and would have to
'learn' it all over again!. I think that with simple components like counters and dividers
and common logic IC's you could easily do this but having said all that I would probably
end up building a multi-function device that had bar graph, digital display and a switch
to switch between different functions like temp, voltage and other non essential
readings.....but then I would start thinking aobut adding threshold warnings and if I was
going to take it even further, peak hold and data logging on a PC based device....then if
I had all the time in the world and no other projects a full blown vehicle managment
system that tried to elliminate copper in the car through the use of a bus and control
modules for each discrete unit in the car like tail lights, dash lights, engine
management.....bah bla...sorry....

you should be able to pick a nice square wave out of the ECU or ignition computer or one
of the pins but that depends and I think that another list member should have more
specific info for you and your car :)

Lachlan. (ranting)


> >Since RPM seems to not need high accuracy you could do it with a LED array
> >of say
> >50 LED's for an accuracy of 120RPM and a range of 6000RPM...how does that
> >sound? I
> >guess it would start to get expensive WRT the drivers but leds are
> >cheapish.
>
> That sounds like a great solution, but I don't know where to start.  Where
> is a good place to pick up signal that I'll be dealing with.  To give you an
> Idea of my experience so far, let me tell you a little bit about myself.  I
> am currently a sophomore attending Cornell University as a physics major.
> Over the summer I did get some experience programming the AltiVec unit on
> the G4 processor and doing some code vectorization.  I know a lot about
> cars, but their electronics are quite foreign to me.  My Car experience
> includes taking an ASE certified course in Automotive Performance, and I
> have also restored a '68 Caddy Deville Convt.  In terms of electronics I am
> currently taking a course on circuits and such, but the year has just
> started, and I have yet to learn anything useful.  As of now I can put
> electronics together, but I have little to no understanding of designing
> circuits, and what the specific parts do.
>
> That being said, is anyone out there willing to help be design and implement
> this "led" tach?  I would greatly appreciate it.

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