Someone pointed me here so I may as well reply publicly:
The BrickRPM design was decent, but in striving for compact design, there was excess trace coupling. It only showed up when I was heat testing it with 110v AC mains into it. In such a scenario the coupling was enough to cause the output signal to not be faithful. This was never struck in the real world by any of my customers. Their only complaint was that I didn't make more!
Some useful info that I wrote 7 or so years ago here:
http://brickems.com/brickrpm/install/ and here:
http://brickems.com/brickrpm/comparison/ and see here for exactly how small:
http://brickems.com/brickrpm/
It was basically designed for people to replace the terrible MS circuit with something high performance in the prototype area, however over half of the stock went to industrial control applications! :-o
With respect Volvo 60-2 MAX IC performance, how high are you buggers spinning these poor things? I've tested to
8k RPM on a whiteblock with zero issues. 5k is all I can currently get out of my B234F with MAX but not due to the max, due to a slew of other issues on the car that I need to work through. Also used on a different pattern to 12500 RPM on a CBR600RR
With respect to Bruce's comments, he first refers to the issues that guy had as being the fault of the max chip, and only later specifies that ADDING a shunt resistor FIXES the issue - and also that not all VR sensors need one at all. All of that is absolute crazy talk. The shunt resistor is basically REQUIRED or you'll have APPALLING high input impedance and susceptibility to noise. It can be tuned in value for problem applications, however in all the years I've been using them a value in the 1k to 5k has served me well when combined with 10k voltage clamp current limit resistors. The BrickRPM board doesn't have one to make sure it's tunable due to being an SMD design. The ancient docs suggest that you don't need the shunt, but encourage its use. I would now say the docs were a bit wrong by not mandating use of one.
I would suggest that if the MicroSquirt has issues at higher RPM on a Volvo 60-2 then there are other factors involved such as, but not limited to, circuit topology issues, PCB layout issues, wiring routing issues, etc. For example, in a boosted application with rising RPM comes rising cylinder pressure which causes ignition coil voltage to markedly increase prior to spark gap break down and discharge. And let's be honest, the vast majority of MS users on here are running one because they're boosting and/or boosting outside the stock capability. Or maybe MicroSquirt just doesn't have a shunt in place by default? Don't know and don't care. My stuff works