magnetic field

[Bob Monsen]

Jerry Avins wrote:

Al Clark wrote:
Unfortunately (fortunuately) I have a pretty good sense of pitch.


Mine comes and goes.

I have a friend who claims to have had perfect pitch until her 55th
birthday or thereabouts, at which point her perfect pitch started to go
low (or high, I can't remember which). Anyway, it disturbed her quite a
lot, because it made her favorite recordings seem out of pitch. I guess
it would be like having all your green things suddenly turn yellow. You
might get used to it, but it would be disconcerting.

Regards,
Bob Monsen

 

[Jerry Avins]

John Woodgate wrote:

I read in sci.electronics.design that Jerry Avins <jya@ieee.org> wrote
(in <brydnYP4-My62_DfRVn-3w@rcn.net&gt about 'DIGITAL GUITAR AUTO-TUNER
PROJECT', on Mon, 25 Apr 2005:

Even though I have no idea what s.e.d. stands for,


It stands for a very great deal, and it's the newsgroup you are
participating in.

Ah! I'm subscribed to comp.dsp. Ain't cross posting fun?

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ

 

[Jerry Avins]

Jon Harris wrote:

"Jerry Avins" <jya@ieee.org> wrote in message
news:brydnYP4-My62_DfRVn-3w@rcn.net...

John Woodgate wrote:

I read in sci.electronics.design that Jerry Avins <jya@ieee.org> wrote
(in <H96dnVy_aYL0nfDfRVn-gw@rcn.net&gt about 'DIGITAL GUITAR AUTO-TUNER
PROJECT', on Mon, 25 Apr 2005:


He was quite taken with the selectable temperaments on my recently
acquired Yamaha "piano".

Can this feature be retrofitted to s.e.d contributors?

Even though I have no idea what s.e.d. stands for, I doubt you can
implement selectable intonation without getting into the firmware.


s.e.d. = sci.electronics.design. I think this was a joke, playing off the word
"temperament". Get it?

I do now. It's a pretty good one for off the cuff, as it were.

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ

 

[Jerry Avins]

Bob Monsen wrote:

Jerry Avins wrote:

Bob Monsen wrote:

Jerry Avins wrote:

Ville Voipio wrote:

...

Nononononnononoooooo! If you tune it to the "even-tempered" scale,
the result is very bad-tempered. All the fifths are bad, all the
thirds are bad.





Ah, come now! Even in the best of guitars, the frets are located by
"the rule of nineteen". Pianos and fretted instruments have tuning
similarities (although you can't "bend" a piano).


Apparently, the very high and very low notes on pianos are tuned with
a larger than 2:1 octave. The ratio can be up to 2.025:1. The
claim(1) is that that this is caused by beat matching, trying to
match the fundamental to the 2nd harmonic, which is slightly off due
to the stiffness of the strings.

Thus, it may not make sense to do precise electronic tuning on
stringed instruments. I always find that my guitar sounds better when
I match the harmonic on the 5th fret of the bottom string to the top
string, and then interpolate. That makes the high E somewhat sharp
(but not nearly as sharp as a piano, due to the lower string tension.)

(1) Musical Acoustics, Donald Hall, pg 188.



A piano's "stretch" over its 7.5 octaves is the better part of a
semitone. By attaching discrete weights to the strings, most of the
inharmonicity can be removed. (The windings on the low strings end
well short of the bridges, reducing inharmonicity of the second
partial.) A piano so doctored is tuned without stretch. It sounds awful!

Jerry



That is interesting. The book I referenced mentioned another possibility
for why the stretch occurs. The human ear has far less ability to
discriminate pitch at low and high frequencies than it does in the
middle range. The other possibility was that the extra bit was required
to overcome this inability, forcing the ear to hear an octave. However,
the text also states that studies by Backus indicate that the mechanism
of string inharmonicity accounts for most of the stretching..

I guess you have listened to these pianos. Do the high strings sound flat?

Not so much flat as dull. Even single notes. Vladimir Horowitz
disparaged the notion of changing the sound of a piano by the way one
strokes the keys. He said, "There is such a thing as pianistic touch,
but it cannot be demonstrated by playing a single note." Nevertheless,
if we pretend for now that "touch" matters, a piano corrected for
inharmonicity sounds to me as if the pianist were wearing thick felt
gloves. The notes have no ... sparkle? We don't have the words. Have you
ever improved a stew by adding a little vinegar? Inharmonicity is a
piano's vinegar. Hammond organs are harmonic.

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ

 

[Jerry Avins]

Ville Voipio wrote:

...

The idea of fixed frets is
a new one, older instruments tend to have movable frets.
My viol (viola da gamba) has tied frets, and I really have
to move them depending on the temperament. Actually, the
deviation from even temperament is very visible (some
frets are closer to each other than others). And talking about
bending... some of the frets are actually non-horizontal
to give better temperament.

Classical guitars have a tilted bridge (bridge compensation), so in
effect, all its frets are non horizontal.

[fine discourse snipped]

(I just wonder if there was anything not off-topic in this posting?)

So what if there were? Anyway, with all the cross posting, there bound
to be some groups whose charters touch on every part, but probably none
that touch on all.

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ

 

[Jerry Avins]

Ville Voipio wrote:

...

The tuner is quite fine with violins, flutes, and even piccolo flutes,
but not very good with cellos, double basses, bass viols or other
low instruments. It does find the correct note, but the detection
is then very sensitive to higher-frequency noise.

That seems to suggest that good performance depends in part on a
low-pass filter, and that the cut-off is higher than optimum for low
instruments. That also suggests that an improved model might have a
variable filter or a choice of fixed ones. It tales longer to count
cycles in low notes, but I think that effect must be secondary.

...

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ

 

[Bob Monsen]

Jerry Avins wrote:

Hammond organs are harmonic.

That describes it quite well.

Jerry

 

[ehsjr]

Watson A.Name - "Watt Sun, the Dark Remover" wrote:

<snip>

And it makes sense. I'll try a diagram.

+------+-----------------+
| | |
| Mosfet |
___ | B
___ +------|<----+ A
| ( | T
| ( L1 | T
| ( | E
+------+ | R
) | Y
) L2 | |
) | |
-----------+------------+----+

snip


The desulfator article uses two separate inductors, I don't see how
you're doing it with one.

It is one toroid, but it has two inductors wound on

it, with one continuous piece of wire. Just like
a center-tapped inductor, except (see diagram) L2
is wound in the opposite direction from L1.

I tried to reply to this twice before with an
attached picture. I'm guessing that the attachment
is the cause of the problem. I'll try to post
a picture of it - look for Contra-Wound Toroid.

Ed

 

[Al Clark]

Jerry Avins <jya@ieee.org> wrote in news:brydnYP4-My62_DfRVn-3w@rcn.net:

John Woodgate wrote:
I read in sci.electronics.design that Jerry Avins <jya@ieee.org> wrote
(in <H96dnVy_aYL0nfDfRVn-gw@rcn.net&gt about 'DIGITAL GUITAR AUTO-TUNER
PROJECT', on Mon, 25 Apr 2005:

He was quite taken with the selectable temperaments on my recently
acquired Yamaha "piano".


Can this feature be retrofitted to s.e.d contributors?

Even though I have no idea what s.e.d. stands for, I doubt you can
implement selectable intonation without getting into the firmware. In a
YDP-233, one can chose among equal temperament (the default), or pure
major, pure minor, Pythagorean, mean tone, Werkmeister, and Kirnberger,
all with any base note. You can also transpose any number of half tones
and pull the pitch of A440 in about .2 Hz increments from 427 to 453.
It
doesn't sound like the Steinway it replaced (my daughter has that now),
but it's fun to play with as well as on. It will record two tracks and
has a MIDI interface. More than I need.

Jerry

Sounds like fun! but I'd take the Steinway.

Al



--
Al Clark
Danville Signal Processing, Inc.
--------------------------------------------------------------------
Purveyors of Fine DSP Hardware and other Cool Stuff
Available at http://www.danvillesignal.com

 

[John Woodgate]

I read in sci.electronics.design that Bob Monsen <rcsurname@comcast.net>
wrote (in <Aq2dnRIVloHcwPDfRVn-qg@comcast.com&gt about 'DIGITAL GUITAR
AUTO-TUNER PROJECT', on Mon, 25 Apr 2005:

I have a friend who claims to have had perfect pitch until her 55th
birthday or thereabouts, at which point her perfect pitch started to go
low (or high, I can't remember which). Anyway, it disturbed her quite a
lot, because it made her favorite recordings seem out of pitch.

Look for a winding handle at about waist-level. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[John Woodgate]

I read in sci.electronics.design that Jerry Avins <jya@ieee.org> wrote
(in <X6WdncXj2cQk__DfRVn-sA@rcn.net&gt about 'DIGITAL GUITAR AUTO-TUNER
PROJECT', on Mon, 25 Apr 2005:

So what if there were? Anyway, with all the cross posting, there bound
to be some groups whose charters touch on every part, but probably none
that touch on all.

An ichthyology group should be added, so that tuna experts can
participate.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Tony]

I'd be interested to read that article - can you recall the issue, or
even the year?

On Mon, 25 Apr 2005 19:38:33 +0200, Guillaume <"grsNOSPAM at
NOTTHATmail dot com"> wrote:

John Woodgate wrote:
Meanwhile, no commercial tuner that I know of uses an FFT.

How do they work, then? (The answer 'Very well' is not acceptable.)

Most of them use a simple design. You can find one on CircuitCellar,
and that's pretty much how this is done in commercial products.

It consists of an input stage, which is basically a good low-pass filter
filtering everything above the maximum fundamental frequency it's
supposed to deal with (probably something like 1000 or 1500 Hz), usually
a 2nd order active filter. Then it's followed by a comparator set with
some hysteresis, which can also be an amplifier based on some AOP with
a lot of gain - so that the AOP clips the signal, which is easily
transformed into a digital signal with a schmitt trigger, for instance.
This circuit basically extracts the fundamental frequency of the input
signal with a reasonable usability.

Then the comparator's output can be dealt with in various ways.
Some can be rather crude (just measuring the frequency of the resulting
digital signal), some are more clever, and I like the one that's used
in the CircuitCellar project. The comparator's output goes to a digital
I/O pin of a microcontroller, of course set as an input. The algorithm
used consists of measuring the delay between two consecutive raising
edges - but this is not all. To make sure the measure is meaningful,
several consecutive measures are compared, and only if we get a few
(like 10, for instance) consecutive measures that are close enough
to one another, do we consider this is the fundamental frequency.
The latter is computed from the period, using for instance an average of
the 10 given "meaningful" past measures.

By comparing the frequency with a few preset ranges, the tuner can
even guess what the string it is you're trying to tune, and
automatically give you how far away you are from the nominal
frequency for this string.

As to how the above input stage, based on a filter and a saturation
stage, translates in the frequency domain (in other words, how
the spectrum of the original signal is transformed), I'll let you
think about it. It resembles, but is not quite like simply looking
at zero-crossings - because the saturation on the signal actually
tends to "ignore" the harmonics, whereas simple zero-crossing
analysis has to deal with them.

All in all, this is a working approach and it's much simpler than any
sophisticated DSP analysis you might try.

Tony (remove the "_" to reply by email)

 

[Andre]

Dont these tuners use PLLs?

Bob Monsen wrote:

dhaevhid wrote:

By filtering a 10Hz passband for each string, it's possible you will be
able to do the zero crossing thing, and then both select the string, and
give guidance on which way to tune as relative error. However, that is a
guess, since I haven't tried it.

---
Regards,
Bob Monsen

--

Please change no_spam to a.lodwig when replying via email!

 

[Richard Owlett]

John Woodgate wrote:

I read in sci.electronics.design that Jerry Avins <jya@ieee.org> wrote
(in <X6WdncXj2cQk__DfRVn-sA@rcn.net&gt about 'DIGITAL GUITAR AUTO-TUNER
PROJECT', on Mon, 25 Apr 2005:

So what if there were? Anyway, with all the cross posting, there bound
to be some groups whose charters touch on every part, but probably
none that touch on all.


An ichthyology group should be added, so that tuna experts can participate.

That sounds fishy.

 

[keith]

On Tue, 26 Apr 2005 11:47:24 -0500, Richard Owlett wrote:

John Woodgate wrote:

I read in sci.electronics.design that Jerry Avins <jya@ieee.org> wrote
(in <X6WdncXj2cQk__DfRVn-sA@rcn.net&gt about 'DIGITAL GUITAR AUTO-TUNER
PROJECT', on Mon, 25 Apr 2005:

So what if there were? Anyway, with all the cross posting, there bound
to be some groups whose charters touch on every part, but probably
none that touch on all.


An ichthyology group should be added, so that tuna experts can participate.

That sounds fishy.

How many newts in the scale?

--
Keith

 

[Ken Taylor]

"keith" <krw@att.bizzzz> wrote in message
newsan.2005.04.27.02.16.24.179681@att.bizzzz...

On Tue, 26 Apr 2005 11:47:24 -0500, Richard Owlett wrote:

John Woodgate wrote:

I read in sci.electronics.design that Jerry Avins <jya@ieee.org> wrote
(in <X6WdncXj2cQk__DfRVn-sA@rcn.net&gt about 'DIGITAL GUITAR AUTO-TUNER
PROJECT', on Mon, 25 Apr 2005:

So what if there were? Anyway, with all the cross posting, there bound
to be some groups whose charters touch on every part, but probably
none that touch on all.


An ichthyology group should be added, so that tuna experts can
participate.

That sounds fishy.

How many newts in the scale?

--
Keith

How many scales on a newt?

Ken

 

[CWatters]

<deepaa@gmail.com> wrote in message
news:1114565054.117886.45800@g14g2000cwa.googlegroups.com...

Wondering if I need to buy a NiMH charger for NiMH rechargeable AA
batteries or a normal AA charger will work with the NiMH batteries. Can
anyone tell me if this is possible?

If it claims to be a fast charger for NiCad cells then it's not a good idea
to use it with NiMH cells. If it's designed to trickle charge cells
overnight then it might work ok.

If your house burns down it's your fault though.

 

[Z80]

My battery charger is marked "Universal Ni-Cd & Ni-MH" and its not that new or special, so I would guess that most chargers would be OK.
Inside the unit, for AA batteries, it says Ni-Cd 500mAh - 5-8hrs Ni-MH 1200mAh - 10-20hrs
It seems like trickle chargers would work - you just have to allow time for the capacity of the battery. (or cell).

Alan

<deepaa@gmail.com> wrote in message news:1114565054.117886.45800@g14g2000cwa.googlegroups.com...

Wondering if I need to buy a NiMH charger for NiMH rechargeable AA
batteries or a normal AA charger will work with the NiMH batteries. Can
anyone tell me if this is possible?

Thanks in advance!

 

[CWatters]

"Z80" <r796coj@noSpam@blueyonder.co.uk> wrote in message
news:0KJbe.20509$G8.12198@text.news.blueyonder.co.uk...

My battery charger is marked "Universal Ni-Cd & Ni-MH" and its
not that new or special, so I would guess that most chargers would
be OK.

Fast chargers designed for NiCad cells (only) should not be used on NiMH.

The reason is because the end of charge voltage peak can be a lot lower
sometimes with NiMH cells - this can lead to the charger failing to detect
that the cells are full and fails to switch off. This leads to over charging
at the fast charge rate and possibly very hot cells or worse.

 

[Dennis Clark]

CWatters <colin.watters@pandorabox.be> wrote:

: "Z80" <r796coj@noSpam@blueyonder.co.uk> wrote in message
: news:0KJbe.20509$G8.12198@text.news.blueyonder.co.uk...
: > My battery charger is marked "Universal Ni-Cd & Ni-MH" and its
: > not that new or special, so I would guess that most chargers would
: > be OK.

: Fast chargers designed for NiCad cells (only) should not be used on NiMH.

: The reason is because the end of charge voltage peak can be a lot lower
: sometimes with NiMH cells - this can lead to the charger failing to detect
: that the cells are full and fails to switch off. This leads to over charging
: at the fast charge rate and possibly very hot cells or worse.

I've found that if I charge at high rates (1-2C) then the NiMh cells will
have a sharper dropoff and the delta peak will work on my old Tekin pulse
(NiCd) charger. If I charge at lower rates (< C) then if often won't
detect full charge and I have to check temperature. However, this
comment comes with caveat emptor and YMMV warnings. I have a 10 year old
(or older?) Tekin BC112 charger, still charging along...

DLC


--
============================================================================
* Dennis Clark dlc@frii.com www.techtoystoday.com *
* "Programming and Customizing the OOPic Microcontroller" Mcgraw-Hill 2003 *
============================================================================