LED tach...
 

One of my tachs is dead and the other one flops around from time to time so I figure it's just a matter of time before it's kaput. I was considering just ditching the tach and going with a big clock in that spot but I do like having an indicator of engine speed so I cooked this up:

tach2 - YouTube

That was just some testing of the LED's to get a feel for it but I finally got it nailed down using a Hall effect sensor to pick up RPM.

I was thinking about putting it (Well, a more refined version) in the PRNDL spot in the dash because it's unused in a 116 SD.

Any input? I'll probably have to dim the LED's at night or something and I was just going to trigger it off a magnet epoxied to the PS pump pulley.

I had also considered gutting the tach and putting the LED's around the outside of the dial on the hash marks and a shift light in the center but the asymmetry would probably bug me...

Very Knight Rider...

May be you need less diodes so that one lit bulb = 1000 rpm?

May be you need more diodes so that one lit bulb = 500 rpm?

May be you need even more diodes so that one lit bulb = 250 rpm?

Do you see what I'm saying? It is pretty in a 1980s Subaru / Knight Rider kind of a way at the moment but it is difficult to get a real impression of engine speed from the set up at the moment. All I get from it is "way too fast" / "way too slow" etc

I understand what you mean but there is only room for 9 round LED's in the PRNDL spot. The spot is occupied by a black painted piece of styrofoam from the factory :rolleyes:

I figure have the green illuminated at idle and have it register in the yellow at hwy speeds and maxed out red at 6000 RPM. I may stick it on the car tomorrow.

Believe it or not this is an offshoot of my ACCII experiments...

I'm no electronics guru but I thought it was possible to get smaller LEDs. How much space do you have to play with (dimension in inches / mm)? Is it the same size as the one on a W123?