http://www.debrix.com/Speedometer-w-Panel-Mount-Digital-Bar-Graph-Tach-p/we125-mca.htm

maybe?

 

or this: http://www.google.com/patents/US4243938

 

http://lumitach.com/

 

That's some retro crap right there...

 

I don't want to buy a prebuilt tach, if I was going to do that I would get the trailtech dash.

 

I don't want to buy a prebuilt tach...

That is great, zabrow, it can be a lot of fun building your own stuff. :thumbsup:

The easiest way to design the tach is to use a micro-controller. uControllers have been around a long time, but recently have been getting more popular. RadioShack has even started selling the Arduion Uno.

Making a tach as you have described would be straight forward. Using the uC, simply measure the time between ignition pulses (high rpm would be short, low rpm would be long). Based on the duration, illuminate the appropriate number of LEDs.

If you have never used a uC, there would be a small learning curve, but there are forums dedicated to using them with many helpful people. If you catch the uC bug, it will start you dreaming about how to hook one up to control your toaster, or electric toothbrush, just for the fun of it. ;D

 

Thanks

I am looking at the Adruion Uno and it says it is USB controlled. How would you program spark pulses into that system? You would have to have the timing coded to input to the board, correct?

 

Here is the Arduino home page, it explains the system way better than I can. Click the "Getting Started" tab, that should answer lots of questions.

First thing I would do is gather the software(free open source) and hardware($35 at RadioShack) and just try to make a single LED blink. After that, dig deeper into the internal timers which would be used to measure the time between ignition pulses.

To connect the Arduino to the bike, you will need to tap the primary side of the ignition coil. A filter is needed between the coil and the Arduion to reduce the voltage and eliminate noise spikes; you can not just feed it directly to the chip. I've already built and tested a filter circuit that will work (original purpose was to allow an SV gen2 gauge to connect to a gen1 bike), so if you are interested, let me know. First thing to do though would be just try to make a single LED blink. In software lingo, this is equivalent to writing your first "Hello World" program...

Good luck!

 

I set up my dad's trailtech dash today for him for his birthday and got to wire the tach and had an idea now that you have shown me the Arduion Uno. If I can program the Arduion Uno to control the lights for say light 1 to come on for RPM ranges of 1-1000 pulses per minute, light 2 to come on for pulses 1001-2000 and so on. If i can send the signal directly to the aduion, it should work. I think

 

Get yourself a Leonardo (or a Freetronics Leostick). I'm thinking you're better off using a frequency converter of some sort, opto isolated to avoid the noise TeeRiver mentions. If you can sort out a circuit, or a link to somebody elses (and you'll find them, I've looked) I'm happy to help you program it. An Uno is a bit big and even more massive overkill than the Leonardo still is.

They're a piece of cake to program, and you'll find a million other things you can do with them.

 

Get yourself a Leonardo (or a Freetronics Leostick).

That is pretty slick!

 

Stuff like this:
http://www.sportdevices.com/rpm_readings/index.htm

Heaps of peoples circuits out there to rip off.