cam and crank trigger combo inside a distributor (megasquirt

[juki48]

The MSD pickup actually kinda sorta sees the teeth, but the missing tooth transition provides ~10X the signal, which says that it's aliasing the rest of the teeth at 12 pitch.

I'll return this and order some Allegro gear tooth sensors, 8mm face. The docs on it don't show minimum pitch, but suspect no issues, it can even tell which direction the teeth are going.

Thanks for sharing. my sensor is on back order and will be a few weeks before I get it. I'll post updates when I have some. regarding the gear tooth sensors, from what I found most hall based ones require about a 5mm tooth and gap. I did get engineering feedback form cherry sensors in regards to this. they did say the tooth size could possibly be smaller but did not go into detail what was required. I did not look into the allegro 8mm sensor.

[Piledriver]

I placed a small Digi-Key order last night, bought 4 sensors, two of the 3 wire ATS667LSG and two of the newer 2 wire ATS685LSH type.

...Amazingly sophisticated little buggers the size of your pinkie nail, for ~$7.

[MarioVelotta]

Crap, should have checked this out sooner. I found that the 667's don't work on this small of trigger wheel, and not much luck with the 2 wire versions either... But this 3 wire does the job well.

[Piledriver]

Bummer, and ... cool.
The wheel I'm playing with is much larger than that, so there is still hope.

If all fail I'll have plenty of VSS for traction control now

Inquiring minds really want to know which itty-bitty sensor that is

[MarioVelotta]

Bummer, and ... cool.
The wheel I'm playing with is much larger than that, so there is still hope.

If all fail I'll have plenty of VSS for traction control now

Inquiring minds really want to know which itty-bitty sensor that is

I used the 627 version

[Piledriver]

Bummer, and ... cool.
The wheel I'm playing with is much larger than that, so there is still hope.

If all fail I'll have plenty of VSS for traction control now

Inquiring minds really want to know which itty-bitty sensor that is

I used the 627 version

Wild, you would never see the difference looking at the datasheets.

[juki48]

I finally got my crane cams optical trigger. modeled it up today to see how it will fit. I can just fit a 1.75" disk in there
here is 12-1 with 1/16" slots.

here is 16-1


do you think 12-1 is enough or should I try for 16-1? with the 12-1 the space between the slots will fully eclipse the optical sensor's LED. with 16-1 it doesn't quite cover it but I'm not sure that matters. also, I could cut wider slots on the 12-1, maybe 3/32. what do you think? I have the disk turned and just need to mill the slots and drill/tap for set screws to attach it to the shaft.

[Piledriver]

The more the merrier, but the Crane sensor may have a response//effective RPM limit.

I have temporarily run into ~that on my 36-2 setup due to the LM1815 setup I have in the MS3.
(works past 9K on my MS2 on the bench , shuts off hard at 4900 in the car setup)
There is an easy fix, but it requires an hour I don't have until the weekend if I am lucky.

I had a rubber 2" cap in my hand today at HoDepo:
I think I'll mod a stock distributor cap with a big clear plexi window on top.
(So as not to guess doing valve adjustments, getting up/down/up from the floor at my age is to be avoided )

Note:
AFAIK the number of teeth must still be even when divided by 2 (at crank speed), so 8, 12, 16, 20, 24, 28, 32, 36 etc are valid. OTOH you can have any (reasonable) number of missing teeth as an uninterrupted set.
(so 36-1 is valid, as is 36-2/3/4/5/6 as long as all the missing teeth are together)
This worked out for me when I overcooked a tooth with the TIG.

[Steve Arndt]

Or just run without a cap or cover. It confuses casual observers... (joking, that was just for testing)

http://www.youtube.com/watch?v=FxEFLSSstG8

[Chip Birks]

Thats what i've been doing for two years! Just no rotor!

[juki48]

The more the merrier, but the Crane sensor may have a response//effective RPM limit.


Note:
AFAIK the number of teeth must still be even when divided by 2 (at crank speed), so 8, 12, 16, 20, 24, 28, 32, 36 etc are valid. OTOH you can have any (reasonable) number of missing teeth as an uninterrupted set.
(so 36-1 is valid, as is 36-2/3/4/5/6 as long as all the missing teeth are together)
This worked out for me when I overcooked a tooth with the TIG.

I wish I knew how wide the slot and flag needed to be for the crane sensor. I may just go with the 12-1 using a 3/32 end mill for the slots. I'm confident that will work. If I have time maybe i'll make a 24-1 with a 1/32 endmill or something crazy just to see if it can handle it.

[Piledriver]

Lacking data (and even sometime if you have the detailed datasheet) the only way to KNOW is to commit to metal.
Based on my initial testing the `667 sensor was not going to work with the gear I was trying to use...
But it worked beautifully with a FILLED "missing" tooth (touch of weld)

But in your case, all you need is mylar or polycarbonate. No complex milling required at ALL.

You have an optical sensor. You can PRINT your wheels on clear plastic sheet on a std laser printer.
(I'm pretty sure Cranes wheels were clear printed plastic)
The Fedex store is calling you.

Just design a good holder/support in metal.
You could probably get away with bog std transparencies... Even ink jet ones for testing.
Print 20 wheels to try at a time.
Perhaps design a punch setup to cut them out neatly.

[juki48]

this is what I made, and have since black anodized the wheel. the crane 700-0020 is NOT a 12v sensor! I have read it is 5v but I think it is actually only rated for 2v as 5v with no resister blew the led. the 715-0020 says it is rated for 12v, haven't messed with one though

[Piledriver]

Beautiful, that should work fine.

[Redline Weber]

HI Guys, just REMEMBER 12-1 "gear down" is ONLY 6 teeth on the Crankshaft.

This is a bit low for position prediction (6-8 degrees) guess@2500/second.

Lance