Speeduino

Hello everyone. Trying to get to the point of driving my 84 VW GTI project and I am needing to track down a VR or hall sensor for my cam sensor. Sounds easy right? I seem to be allergic to doing things the easy way. I gutted the factory VW 1.8 distributor and pressed a 36-1 wheel on the distributor shaft. This means the gear is pretty small, like 2 inch diameter small. The teeth on the wheel are about 1.5mm at the points and the gaps are about 2mm. Thus the complicated part. I m able to find sensors for a 3mm tooth relatively easy. I was able to find this hall sensor that is advertised as a 2mm tooth with a 2mm gap, which I could get my teeth to 2mm if I turn the gear down a little bit, but Mario has his shop disabled and I am needing to get something going quick. https://thedubshop.com/crank-sensor-hall-effect/

Wondering if there is anything with the same specs available in either Hall or VR that I can get online or if you know of one I can pull at a wrecking yard even better. Let me know!
Thanks
Hunter

@hunters628

Is an optical sensor an option? It's treated as a hall sensor.
I'm looking to use this one.

Unfortunately an optical sensor wouldn’t work for the way I have this setup. If I had a different wheel to use I could make it work no problem. Here’s a picture of what I have so far.

This one:
https://www.allegromicro.com/en/product ... ics/ats627
Does work on a steel wheel, but you need to make some housing for it.

Problem on the OEM sensors is that they don't share the datasheet.
This one does:
https://switches-sensors.zf.com/us/wp-c ... _11_17.pdf

In a general sense, the small teeth and low speeds (half-crank speed) call for a digital sensor, such as Hall, MR/GMR or optical. Optical could be possible as a look-down (top-edge-reading) or possibly a side-reading (black wheel with white/natural tooth tips) configuration, but the tooth tip area is small. Reflective optical have been run in distributors with printed paper wheels for "extended" periods.

Hall would need small-tooth capability (small aperture & angle), and the ATS617/627 type is one possible example used previously. Mounted on breadboard across the inside of the distributor body window (trim breadboard length for sensor clearance) or on standoffs could position it. While even the Honeywell, Littelfuse (3°+3° aperture=calculate it) and ZF types may work, testing will be required as the application is probably out-of-spec for any of those.

Note in your searches that some are called automotive crank-wheel sensing or transmissions sensors for typically larger "teeth", while others are industrial gear-tooth sensing where many are designed for smaller gear "teeth". No guarantee of that, however, and useful spec's are limited. Please post your findings, so the next user does not have to repeat the experiments. There are success threads of tiny wheels (~25mm?) here, but info sharing was unfortunately limited.

Looking at the setup you have, I can't see a missing tooth (not that you can see something that is not there ).

PSIG wrote: ↑Wed Jun 01, 2022 4:52 pm In a general sense, the small teeth and low speeds (half-crank speed) call for a digital sensor, such as Hall, MR/GMR or optical. Optical could be possible as a look-down (top-edge-reading) or possibly a side-reading (black wheel with white/natural tooth tips) configuration, but the tooth tip area is small. Reflective optical have been run in distributors with printed paper wheels for "extended" periods.

Hall would need small-tooth capability (small aperture & angle), and the ATS617/627 type is one possible example used previously. Mounted on breadboard across the inside of the distributor body window (trim breadboard length for sensor clearance) or on standoffs could position it. While even the Honeywell, Littelfuse (3°+3° aperture=calculate it) and ZF types may work, testing will be required as the application is probably out-of-spec for any of those.

Note in your searches that some are called automotive crank-wheel sensing or transmissions sensors for typically larger "teeth", while others are industrial gear-tooth sensing where many are designed for smaller gear "teeth". No guarantee of that, however, and useful spec's are limited. Please post your findings, so the next user does not have to repeat the experiments. There are success threads of tiny wheels (~25mm?) here, but info sharing was unfortunately limited.

Looks like the ATS617/627 and other similar sensors give an example of a 120mm 60 tooth gear, and a specification of 3 degrees tooth width "relative to (sensor) package." doing the calculation that comes out to approximately 3.1 mm tooth width. Ill have to look into optical sensing or just junk this gear and go with a 24 tooth. I just thought it would be nice to have the extra resolution.

LPG2CV wrote:Looking at the setup you have, I can't see a missing tooth (not that you can see something that is not there ).

I haven't cut the tooth off yet. I was waiting to see where the sensor would mount and take the tooth off near TDC.

I have a development in the case! Spent a couple hours today scouring the web and came across NVE corporation and this video they made. https://www.nve.com/Videos/tiny-gear.mp4 They use a "ABL-006" sensor in the video. They sell this sensor package for just over $5 each. It is a surface mount package that is biased with a small magnet. I am thinking about picking one up and making a small board for it. I can 3d print a housing to mount the board and magnet in so it will be nice and close to the gear. I am going to email them explaining my application and make sure this sensor is the best option. Looks like I am heading in the right direction!

if you can mount the sensor, you can proto type a wheel and get it cut.

Awesome on the GMR micro-option! Nothing like excess capability, and a day at the beach for that sensor it seems. However, I would not give-up on more common solutions. I know they are out there, I just don't have examples at my fingertips.

Your project using GMR can also prove-out both smaller profiles and precision capability, while establishing GMR sensor integration as another strong option to older tech that has been waiting for us to catch-up. Do your thing!