Reducing noise from magnetic pickup speed sensor

Other Hardware Sensors
1

I have an 85 CJ-7 and I have been in the process of building a more sensible dash (Partially because the stock one was more rust than dashboard). I am moving away from a cable driven speedometer, but I am having issues with signal conditioning of the VSS I picked up:

I can get a good reading up to about 40MPH, but after that it goes to crap. I suspect part of the issue is the insane amount of electrical noise generated in the engine bay, where the signal wires are routed.
I have switched power from the battery available where the sensor is, and I was thinking of putting something active at the sensor to clean up and boost the signal before it gets sent to the display. My problem is figuring out what that should look like. Should I go basic as something like an op-amp or as far as RS-485 or a CAN protocol? Anyone have experiance with this kind of stuff?

2

What signal conditioning have you done? Have you converted the AC signal to a DC pulse, 0-5 volts as required for your Arduino?
Did you use twisted pair and perhaps shielded to bring the AC signal to the dash?
Paul

3

Shielded wire is needed in this environment at a minimum I suspect. Or change to shielded plug-leads.

4

It would be a tremendous help if you could put an oscilloscope on the signal arriving at your Arduino, and post the trace here. Or at the very least describe it.

5

This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.