Hey, over the past 4 or 5 years I've been doing track support for the SE30 group and quickly got tired of the continuous issues we had with the bosch AFM. This led me to developing a digital drop in replacement which has performed extremely well in some pretty demanding environments (sebring middle of summer).

I was curious if you guys have had similar issues and if anyone had a bad one laying around I could take measurements on to see if my design would drop in.

I have some details on the design here
Design ppt

Thanks
Pete

 

Very cool stuff. Thanks for the posting. I read the PPT.

I think the AFM is one of the problem issues on these cars. I bought myself a spare many years ago, just in case ...

BTW, my old and sold '81 aircooled VW Vanagon had a very similar design, with similar problems (and fix).

One thing I noticed when looking into the design was that they seem to have a relatively complex calibration capability, where they can dial in the resistance / voltage drop as the wipers travel across the whole curve. Of course complicated to do in analog hardware should be pretty easy to do digitally. I assume you've done this, so what did you find regarding the calibration procedure, etc.?

 

Yes you're right it's much easier to do a curve in the digital world vs analog. Part of my hope is that I'll find I only need to tweak the curve in my code between these different cars and that the physical implementation is exactly the same.

For the e30 i found the curve to be relatively linear with a small kink in the early stage. Some of my struggle was that I don't have access to Bosch data so to determine what the curve should be i took measurements on a bunch of used AFMs j had access to. I seem to be in the ballpark, all the cars wanted a slightly different curve to build the most power but there's a happy medium.