Over 19,000 RPM on a bench test...
 

http://images.wikia.com/dragonball/i...9000Techno.gif

Sorry couldn't pass up

(Posting from my phone.)

Intense.

My BP revs to 30k. Step your game up:D

if that flew off you would die

Holy crap! exactly what i was thinking.

What hall sensor is that?

19,000 RPM? Danger to the manifold.

lol

Seems like you'd want some kinda shield there....pretty cool, though.

This was my immediate thought - you are a brave man.

It's welded pretty solidly.

I think we are going to build a scattershield around the wheel, but more so to keep fingers out and for sound containment.

Now do that with a CAS.

When things spin at 19k rpm and they don't sound like an F1 car, it's a little depressing.

Right up until the welds crack due to vibration at ~19k. Cool test, but don't kid yourself about how safe that rig really is. I'd be sitting in the next room with a plexiglass shield and a wall in between me and the sensor.

Kudos, but un safe. extremely.

Maybe you did more balancing than we know of, but a weld? Jesus I thought it was bolted on, that's even worse if there wasn't any balancing.

let's put some speed in it lol

Well that seems like something i would walk past and get my shirt hung in for sure. That thing needs a plexiglass box to cover it while in use.

Brave, brave, brave Sir Robin.

It's a work in progress; the scatter shield is going to happen pretty soon. It's one of our off the shelf trigger wheels; they're designed to be dynamically balance as is; the welds may not be perfectly balanced though. That will be fixed in the final version of this.

Anybody here at the Virginia MegaMeet where Bruce demonstrated the wheel decoder - with a circular saw and one tooth cut off the blade?

Awesome.

It'd still scare the crap outta me. Brave Sir Robin wouldn't even be in the same fiefdom as that thing while it was spinning. :D

Just as an FYI, I'm not sure if they're made by the same shop, but the 4" wheel I bought from you guys in '08 (the one with the triangular teeth which actually looks like a saw blade) wasn't quite round. More specifically, the teeth weren't all the same height. It was a very small error, but easily detectable with feeler gauges. This caused me quite a bit of electronic grief until I finally figured out what was causing the resultant (and only very occasionally) misfires. Ultimately, I put the wheel into a lathe and trimmed down the teeth a bit, flattening them out and making them all the same height relative to the center of the wheel.

They are made in the same shop - we may revise the 4" trigger wheel tooth profile, as the laser can sometimes burn the tips of the sawtooth corners. The larger wheels don't have this issue as the edges of the teeth are arcs and not corners. Thanks for the notes on it.

Yeah, merely flattening (roudening, technically) the tips of the teeth down to 2 or 3mm will improve the performance. After I trimmed mine, I got much stronger signal out of the VR sensor. Makes sense- flattening the teeth put a larger mass of metal nearer to the sensor.

Any reason why that wheel had triangular teeth in the first place as opposed to the more conventional tooth design on the other wheels?

It was quite perilous.

Concerns that the sensor needed a minimum gap width to trigger effectively.

Jerry is a nut. I'm glad he is still in one piece. I can't decide if the best part was watching the RPM gauge wrap around twice or his statement at the end "It's got some pretty good range"

Ah, gotcha.

Here's a shot of what the signal coming off my 4" wheel looked like prior to lathing it:

http://img401.imageshack.us/img401/9...ap1666rws8.gif

As you can see, there's significant variation in the amplitude of one pulse to the next, and that first tooth after the gap barely made a zero crossing. The squarewave at the bottom is an LM1815 struggling to deal with the signal, and failing. It missed a pulse because the amplitude of it was so much lower than the previous one.

The MAX9924 did a much better job of decoding this signal, but it would still misfire maybe once or twice a day.

After I lathed the wheel and flattened the teeth a bit, the signal became much more uniform, and the amplitude of the signal increased as well, so much so that I was able to run a significantly wider gap and still have zero misfires.

That's an interesting phenomenon that occurs when using a VR sensor and a missing tooth wheel at the first tooth after the gap. Below is an example of the same thing using an OEM BMW 60-2 wheel and VR sensor. Blue trace is raw sensor, red is post conditioner (MAX9926).

It sums up why I prefer to use a hall sensor as possible.

I find that rather interesting.

This is the "after" shot of my setup, with the flattened teeth, doesn't show any problems at all on the first tooth after the gap. You couldn't draw a more ideal waveform with a pencil. Same sensor and wheel as the earlier image, just with the tips of the teeth ground down to have a 2-3mm flat section:

http://img37.imagefra.me/img/img37/6...8m_f7f8d08.gif

Note the scale on trace 1: that sucker is putting out more than 5v p-p, and this is merely idling. A

lso, the decoded trace is now being supplied by a 9924, whereas in the first image I posted, I was testing the LM1815.

Old thread, image hosting has eaten the images of failing LM1815 :( Does anyone still have a copy of these images by any chance?