Digital Tach

[steve ravet]

I don't know how much experience is "little", but I think that a digital
tach will require some kind of micro controller to interface to the
display (LCD?).  That means you'll have to do a little programming, and
you'll have to have some equipment to write the program into the
microcontroller.  This'll mean some money up front for software and
hardware, and some time learning to program (unless you already have the
programming experience).  I've used PIC microcontrollers in the past
(www.microchip.com), available from digikey.  I've heard good things
about Atmel and will probably try one in whatever my next project is.  

With that said, the way I'd proceed is to take the tach signal through
an opto-isolator and into your microcontroller.  Pick a microcontroller
that has PWM hardware built into it, it'll make it easier to measure the
time between pulses.  Manipulate the units to get the time measured into
rpm, and then display that onto the LCD.  LCDs can be had cheaply from a
lot of surplus electronics, start at www.eio.com.  If you get a 2 or 4
line one then you'll have space to display other info in the future. 
The interface to them is dirt simple, I've got some PIC code that I can
send you for driving them if you want.


--steve

Santi Udomkesmalee wrote:
> 
> I'm pretty new to the DIY EFI scene and I though I would start small on my
> first project.  Unfortunatly, I don't even know where to start.  I'm
> interested in building a digital tachometer for a '98 Chevy Cavalier.  Does
> anybody know how I would go about this?  Currently a have very little
> electronic experience, so the more specific you are the more it will help.
> Thanks a lot.
> 
> -Santi Udomkesmalee


-- 
Steve Ravet
steve.ravet at arm.com
ARM,Inc.
www.arm.com
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org