[DStage]

Here's my new design - a VR conditioner I'm planning to use with Speeduino 0.4.3b. I'll need just one channel but I made it double of course.
The circuit is slightly enhanced and modified version of that used in MS so it is vastly proven in action. It should work with simple LM324 but in corner temperatures the high output level may have very little margin over ATmega tolerance. Therefore I'd rather recommend using rail-to-rail OP amp such as MPC6004 which actually is at the same price level (meaning it's cheap , 0.50-0.60 Euro).
The board is 30.5mm x 27.9mm in size. I'll order it and in the meantime I may test it using identical circuit on one of my other projects. If anyone is interested I'll be happy to share gerber files.

[PSIG]

Simple but effective. No single design has proven to be the answer for every case (as shown by MS users), but simple like this should cover many of the basic setups out there, as other similar designs have. A fresh layout with double-sided should get it small enough to fit most of the popular boards out there.

I see you set cutoff for 60T wheels at 10k rpm for both channels. Do you have component values for a low cutoff on the cycle signal? I'm thinking fc <100hz should do it for anything under 12k rpm and a single-tooth cam signal. While you're at it, perhaps component values for a 5k CKP signal cutoff, e.g., 8000+ with a 36T wheel or lower. Flexibility for the user to build for the application may be helpful?

[JHolland]

Its too early in the morning for thinking but that doesn't look like a zero-crossing detector so you will get some timing drift. Also you only have 100nF of local de-coupling but you could be dumping a lot of energy into the 5V rail during clamping so you should have more or you could put a lot of noise on the 5V.

[DStage]

Yep, I've set it to 60-2 wheel but of course it's beneficial to set it lower if one is using different trigger. And to be honest I forgot about the second channel being quite different in terms of frequency No problem though, here are some possible values for different cutoff frequencies:

10kHz (60T @ 10k RMP):
- R2/R5 = 6k8
- R1/R4 = 360k
- C1/C3 = 100p
- C2/C4 = 1n

5kHz (36T @ 8300 RMP):
- R2/R5 = 27k
- R1/R4 = 360k
- C1/C3 = 100p
- C2/C4 = 1n

100Hz (1T @ 12k RMP):
- R2/R5 = 47k
- R1/R4 = 1M
- C1/C3 = 2n2
- C2/C4 = 22n

As for the "double sided" I assume you mean double sided component placement. I did consider making such version, I'll give it a try.

[DStage]

Its too early in the morning for thinking but that doesn't look like a zero-crossing detector so you will get some timing drift. Also you only have 100nF of local de-coupling but you could be dumping a lot of energy into the 5V rail during clamping so you should have more or you could put a lot of noise on the 5V.

Granted, there might be a need for bigger cap. Normally I used this as part of a bigger circuit without such issue.
I'm not sure why would there be a timing drift... Do you mean threshold level changing output states at different part of sine wave (le't call it that) depending on signal amplitude? Now when I think about it I might have over simplified the reference as I used this mainly for RPM which wasn't critical in terms of timing. No worries, I'll modify it by having same type of PNP transistor to move the threshold to zero-crossing point (Ube).

[DStage]

OK, give me your thoughts now Originally I had also a pull-up on T3 base to tweak the reference but it doesn't feel necessary (I hope I did not miss some voltage drops).

[DStage]

Manufactured and assembled in 2 days and then stuck for 10 days on customs and travelling for few days through Germany but finally found its way to Poland. Good thing I don't need it asap and it will take a while till I try it out. If anyone is interested I've ordered 10 pieces

[NickZ]

What is the advantage over existing VR conditioner, for example MAX9926?
I use MAX9926 and haven't found any real problems other than people not running shielded wire or sharing the negitive side of the VR's

[DStage]

Besides being cheaper no big advantages. Well, maybe just easier tweaking and poking around for some experiments or special adaptations. It's just a different approach, not that fancy though, for example MAX9926 has a self adapting threshold while here it's constant. I guess I like doing or learning things the hard way

[NickZ]

I was more thinking you may have designed something that might work better for Honda or Toyota.
I am always interested in new designs, but I also like to stick with what i know works.

If you get the chance to test it on a Honda or Toyota type VR please keep us updated