I'll post to it as I go along. (Eat a dick Mach - you cheeky bastard)
So, please post or subscribe to the thread and follow along with me!
**To my friends that have already seen were this thread maybe heading - I ask that you don't ruin the surprise!**
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So, many of you have seen my interior light delay with auto dimming that I make: http://www.e30zone.net/modules.php?name ... highlight=
Hopefully this will spark some creativity from you all to go and explore on your own.
So just what the hell is this? Well, my car is not turbo'ed. No Mega-squirt. I have no real need for super huge gauges all over my dash. I like the stock *look*. But I wanted to add an extra gauge here or there, and yet have the interior look totally stock. So ”“ I'll be needing to "sneak" these in the dash some where. Where is the question. I don't want "pods" of things looking like rice cakes poking out of the a-pillers.
I thought about sneaking it into the instrument cluster - but that requires a ton of work.
How about INSIDE a hollowed out hazard or defrost switch? That would look pretty stock? Not to mention no cutting or drilling - just pop out one of the "blanks" and slide that puppy in. Yea that will do - can it fit? I bet it can.
I happened to have a few extra switches lying around. Time to crack one open.
They take some persuading to get them open. Two small screwdrivers does the trick.
The 20 year old innards spill right out. All I care about is the front of the "bezel/case" and the front "button" - The button is a bit thick and dark, but I have a plan for that.
So - about the only "display" you can squeeze into a hazard switch is a LED bar graph. Perfect for a simple gauge - I don't need a numeric display - just something much smarter than a dummy light - and something less than a laptop riding co-polit.
A quick look at my boxes of parts lead me to the venerable LM3914. It's a linear LED driver. Basically you tell it the limits of the signal it will receive, and then you feed it a signal, and it can drive 10 leds to make a guage.
It's made by National Semiconductor - and it's pretty fool proof. In testing it - I threw 20 volts on it's input pin, and everything else to see if I could fry it - no go - it's a trooper. It's not too happy if you hook it up backwards to power - but that's fixable with a diode.
Next step - pull out the parts - I have dozens of boxes like this.
Fast forward to some internet searches on the LM3914 and I'm 90% there - throw in a diode to protect the circuit, and some capacitors to filter the nasty input voltage of a car, and a few more for good measure...I won't bother you with the details...
After a few hours, I have a good hand drawn diagram - time to fire up the rig...And I have it in the computer - this will help me in the VERY complex part of the project - making the circuit board.
Now if this was 1992, I'd have to face one of these bad boys...
I know the parts I need are in there somewhere!!!!
Oh god - this could take for ever...Luckly - it's all on line...
After some more research - I know EXACTLY what I want. I'll mock up the circuit - and cross my fingers...
And it works!!! Ok - I made it look easy, it's a lot of work.
Next up - is taking it from prototype to the real world.[/url]
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