Building and electronic speedometer adj?
 

Folks,

I recently built a "DIY code reader" using schematics from folks on this site. It was fun and works great.

Now I'm wondering how hard it would be to build an electronic speedometer adjuster. I know that these are currently available for sale for those whose guage is off due to diff or tire changes.

My understanding is that an electronic pulse is sent along a wire to the speedometer. It is this signal that needs to be modified.

Any thoughts?

bump

Like you say they are available.

The pulses are a DC square wave, with "X" being the number of pulses that makes 60mph. Intercepting this signal and electronically altering it to X-yX where y is a constant should be simple enough to do electronically.

You could set it with a GPS , a friend checked both my SD and SE with his and both speedo's were right on.It is a nice thing to know in areas know for speed traps........
William Rogers.......