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Fight it till it's right
607 Posts
Discussion Starter #1
I couldn't really think of a good title for this, but I figured I'd share the schematics here too.

Background story:
When I got my 01 SV650 the tach was simply crappy and I wanted to upgrade to something else. Without much research I went ahead and bought an 03 sv650 gauge cluster and thought I only needed to create the proper wiring.
Long story short, I got a bit of a chat started on svrider and thanks to some great engineers, I was able to get the tach running.

Convert a coil based signal to a 12v signal. If you have a scope, this is what you're trying to do:

Top signal is the 12v output that the tach is expecting (12v pulse per RPM) bottom is the actual coil reading, which is a very high voltage spike (100v+)


A simple circuit that knocks the voltage down and allows the tach to be driven. As a side note the top 12v and 4.7k resistor were removed since the '03 sv650 gauge cluster already has that 12v. Per the ee:
"All the MOSFET does is yank it down to ground. So, the MOSFET is pulling the signal down, not pushing it up. If the tach didn't have an internal pull-up, then the 4.7k in the circuit would be necessary"

If you care to read the original post:
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