Tom M'Guinn

I've been gearing up for a new project and thought I'd share a bit. I may have misspoke in the video about the 200rpm test-spec, since I was looking at the speed sensor at the time, but thought this video may be of interest regardless to show how the sensor gap changes the output...

Dare

Cool test, Tom! Did you spin the flywheel by hand, or is there some sort of motor under there?

The next questions that come to mind: Is there any difference with the bell housing in place? What happens when the sensor bracket / bell housing are grounded?

BTW, any luck with those early DME boards? Did you figure out the ref/speed sensor circuits on those?

--Jay

Tom M'Guinn

I'm still working on those. I suspect it's a conditioned comparator of some kind, but I need to spend a little more time with it. I've been playing with my own circuits to condition the signals, and have discovered that the MAX9926 chip has taken VR signal triggering to a new level. Not sure which systems use it, or if it has issues in the real world, but on the bench it is extremely good at detecting VR pulses and distinguishing them from random noise.

No motor, I use a drill with bristle brush to get the flywheel spinning. It works, what can I say... I 3d printed a hub to mount the flywheel on, which sat over a bearing, but eventually I had the hub made in aluminum by a friend. You can see in the video that even the slightest run-out causes the signal to get stronger and weaker, so the plastic had to give way to metal...

Dan Martinic

Very interesting indeed. FYI through my trials with the FAE brand sensors, I discovered that those are ever slightly different size: I set the gap using one of the FAE brand + .8mm washer and then installed a Bosch sensor in its place, noting a distinct drop in signal level. The difference is so slight that someone using aftermarket sensors wouldn't notice by eye but it could affect signal

KevinGross

Tom, cool video. Thanks for sharing. Where's this all headed?

Tom M'Guinn

I have an idea. Stay tuned.

jerome951

Thanks for sharing, Tom. Cool experiment.