[sdiy] Magnetic field

[Czech Martin]

The hall sensors from Micronas have even a DSP and OTP included,
so manufacturing tolerances can be compensated during probing.

I do not know if you can get any in low quantities, though.

m.c.

> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Ian Fritz
> Sent: Montag, 2. August 2004 14:58
> To: WeAreAs1 at aol.com; jmahoney at gate.net; synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] Magnetic field
> 
> 
> At 05:48 AM 8/2/2004, WeAreAs1 at aol.com wrote:
> 
> 
> >I do agree with Harry, though.  I think optical would be 
> more reliable,
> >predictable and consistent.  There wouldn't be as great a 
> variability as 
> >to the
> >position of the light sources or sensors as there would be 
> with the magnetic
> >system.  I'm guessing that there's a lot of variability in 
> magnetic feild 
> >strength
> >with those tiny magnets, which would require a lot of 
> futzing, I think.
> 
> Think and guess what you like.  :-)
> 
> I've worked with both.  Photo sources and detectors have a 
> lot of part-to 
> part variability.  Also a large temperature dependence.  You 
> can find some 
> discussion of this at my website, where I show a servo 
> compensated photo 
> system used for an opto-based breath-pressure sensor.
> 
> Magnets don't have any significant temperature drift, and the 
> Hall sensors 
> you get nowadays have built-in compensation.  I like the idea 
> of having a 
> software calibration. Mechanical adjustment of this stuff is a pain, 
> especially if you have to do a full keyboard.
> 
> Good luck!
> 
>    Ian
> 
> 
>