I've been making some progress on an LED tach and shift light project. I've based it off of this work:

http://members.tripod.com/~foz11/DIY...al_speedo.html

Made a few mods to get everything the way that I want it.

It will have 8 LEDs
4 Green
2 Yellow
2 Red

It will change from an individual LED (dot mode) up to the 1st yellow LED where all the LEDs will be lit up (bar mode) Should be less obtrusive at road speeds and tach readings - though I'll want to play with it a bit so that it goes into bar mode at about 4k RPM to indicate when revving it too much when the motor is cool. (might change it to the 2nd yellow LED - we'll see) When the last LED lights up, the whole array will flash (Shift NOW idiot )

The design process was interesting. I found that I had to do it all at once, board layout, component selection, box selection, etc. to ensure that all the parts will fit on the PCB and work the way that I want. I did have to do the trace layout 3 times to get it right. Each iteration got a little cleaner and less crowded. I'll still breadboard it up to ensure that the set points and gain work properly. There are still a few things that are ambiguous in the spec sheets for the LED driver (National Semiconductor LM3914) that I'll need to play with. I'm also guessing on the LED brightness. What's visible but not blinding, works at day and night, etc. so I'll order a few extra LED packages. (I was looking at a light level control, but it'll get too complicated, unless I find a vario-resistor that is controlled off a light meter or voltage input)

At any rate, the PCB will be about 2.2 by 2.2 inches small and fit in this box:
http://rocky.digikey.com/WebLib/Hamm...93K%5B1%5D.pdf

It's about 1" tall by 2.6x2.6" - should be small enough to fit on the little shelf under the instrument cluster or on top of the steering column. It will wire into the harness going to the cluster, so it should be a simple install.

I don't think I violated any design rules, though I had to mount one IC on the bottom of the PCB to get the trace routing cleaner - shouldn't be a problem though. I'll also need to machine some holes in the box for the brightness control trim pot and the LEDs. Should be a nice, tight package.

Anyway, I've attached the PCB layout and parts list (missing the box on the BOM though). Anybody that knows PCB layout want to tell me if it's all wrong, I'll be happy to listen.

The cost goal is under $50 and it looks like that can be done.