MicroSquirt.com read only forum (Jan.15,2018)

Hall sensors are because they produce an on off signal aka square wave at a fixed voltage level (5v or 12V IIRC), whereas VR sensors are inductive and produce an AC signal that is proportional to the speed of rotation, and at low revs i.e. cranking this is sometimes around 3V p-p, so it doesn't take much to interfere with this. However, the new v3 MicroSquirt you intend to use is so much better at being discriminatory that I think you'll be OK with this choice. Why not just look for a suitable sized sensor that you can use and afford, and go with that. If you can't get one to fit, you can't use it, so there is some sort of selection process going on straight away, and the other thing that you are missing out on, is all those two strokes and four stroke singles that run up and down the roads, have VR sensors right by and alongside their alternators etc already, so what makes you think you have a special case environment!

24c wrote:Hall sensors are because they produce an on off signal aka square wave at a fixed voltage level (5v or 12V IIRC), whereas VR sensors are inductive and produce an AC signal that is proportional to the speed of rotation, and at low revs i.e. cranking this is sometimes around 3V p-p, so it doesn't take much to interfere with this. However, the new v3 MicroSquirt you intend to use is so much better at being discriminatory that I think you'll be OK with this choice. Why not just look for a suitable sized sensor that you can use and afford, and go with that. If you can't get one to fit, you can't use it, so there is some sort of selection process going on straight away, and the other thing that you are missing out on, is all those two strokes and four stroke singles that run up and down the roads, have VR sensors right by and alongside their alternators etc already, so what makes you think you have a special case environment!

I don't know anything about the others, I was just wondering about this one because I'm not bolting alongside the alternator, I'm bolting to the alternator. If one is preferential to the other, that seems the place to start.

les_garten wrote:...I'm not bolting alongside the alternator, I'm bolting to the alternator..

You are bolting to a lump of metal that is attached to the bike earth/ground, which is the same as most things out there, and actually a little better than some, as inside a flywheel/stator set up I was referring too. The trigger wheel is attached to the rotating part of the alternator, and this is separated from the sensor by an air gap. Unless you have a noisy ground, I doubt the electrical interference will be the issue. If you have a noisy ground it will be no different to a car based alternator environment, and the solutions they use.

24c wrote:

les_garten wrote:...I'm not bolting alongside the alternator, I'm bolting to the alternator..

You are bolting to a lump of metal that is attached to the bike earth/ground, which is the same as most things out there, and actually a little better than some, as inside a flywheel/stator set up I was referring too. The trigger wheel is attached to the rotating part of the alternator, and this is separated from the sensor by an air gap. Unless you have a noisy ground, I doubt the electrical interference will be the issue. If you have a noisy ground it will be no different to a car based alternator environment, and the solutions they use.

Not quite.

In a car, the trigger wheel and pickup are relatively speaking, a long way from the alternator. EMF fields fall off rapidly with distance. That's what i was referring to.

OK, but motorcycle flywheel mounted stators have vr sensors inside their generator environment, and they reliably trigger CDI units etc, so the EMI effect in your installation which is outboard of the alternator windings will be a lot less.

24c wrote:OK, but motorcycle flywheel mounted stators have vr sensors inside their generator environment, and they reliably trigger CDI units etc, so the EMI effect in your installation which is outboard of the alternator windings will be a lot less.

We'll see I suppose. I think I have a hall system sorted out from Moorespeed.

Tough question to really know 100% before trying. I suspect 24C is quite correct tho. In my case with a 36-1 TW and VR sensor, I've had really no reset issues I'd have to say. (early on, perhaps yes occasionally, from other circuits and with different types of wiring runs and shielding) but I've utilizied a couple of different locations for the sensor during upgrades along the way, also my Mitsubishi Alternator has a low rpm excitation threshold whereby it kicks into charge on first start up when raised a few hundred rpm over idle - and non of those have ever resulted in noise. Sensor is about 4" or so from where yours will reside off the case of the stator housing but still very solid.

I am doing a motorcycle install also, and wonder how small can the wheel be?