MOTM

First of all, forgive my ignorance. (I got through Serway's 3rd 
edition of Physics, but that was a fair number of years ago. I freely 
admit to being one of the faceless losers for whom electricity 
is "magic stuff" that comes out of the wall socket.) I understand we 
will need at least a voltmeter for some of the newer modules. I would 
like to be able to perform the full range of calibrations on the 
various modules. So, any advice on which multimeter would be a good 
choice? (Someone mentioned extech instead of fluke because 
the "higher resolution" was better for calibrating oscillators at 
lower frequencies.) I'm willing to spend a few hundred dollars on one.

Next up on the parade of topics which yield highly opinionated 
responses - a soldering iron. I have decided, perhaps foolishly, I 
might be able to pull off a 1/5 or 2/5 difficulty kit without burning 
the house down or irreparably damaging multiple digits. (Since I have 
2 eyes I figure I can live with the inevitable "poking out" of one of 
them.) I want a quality soldering iron that will last but also don't 
need one somebody who does this for a living would get. 
Unfortunately, the Weller model everyone seems to like looks to have 
been discontinued.

The rest of the tools needed to "venture forth" seem pretty 
straightforward. I would prefer to get the soldering iron and 
multimeter right the first time ;-)

> various modules. So, any advice on which multimeter would be a good
> choice? (Someone mentioned extech instead of fluke because
> the "higher resolution" was better for calibrating oscillators at
> lower frequencies.) I'm willing to spend a few hundred dollars on one.

I've got a BK Precision meter that I absolutely love.

> them.) I want a quality soldering iron that will last but also don't
> need one somebody who does this for a living would get.
> Unfortunately, the Weller model everyone seems to like looks to have
> been discontinued.

Metcal. They're quite a bit more spendy than the Wellers, but they heat up
*FAST*.

-->Neil

-------------------------------------------------------------------------------
Neil Bradley             Will work for modules
Synthcom Systems, Inc.
ICQ #29402898

From one faceless loser to another: congratulations on deciding to 
build your own!  It's a very do-able thing, belive it or not, even if 
you don't really understand what's going on.  What makes is do-able 
is the simple fact that Paul has created the ultimate kit.  Great 
instructions, everything you need, and really good explainations of 
the circuits.

I have an $89 yellow Radio Shack brand meter that has served me 
well.  It even has a frequency counter and capacitance measurement.  
So if you're gonna spend two hundred clams, you should be stylin'.

If you spend another $150 on a soldering station, you will be OK.  
Mine has digtal temp setting and has been a real pal for the over 40 
kits I'vve built so far.

When I goof up on a kit, Paul has always been helpful and reasonably 
kind.  SOme of my mistakes were, uh, humorous to him I'm sure!

Let us know how it goes...

Mike

--- In motm@yahoogroups.com, "klstay" <kevinstay@e...> wrote:
> First of all, forgive my ignorance. (I got through Serway's 3rd 
> edition of Physics, but that was a fair number of years ago. I 
freely 
> admit to being one of the faceless losers for whom electricity 
> is "magic stuff" that comes out of the wall socket.) I understand 
we 
> will need at least a voltmeter for some of the newer modules. I 
would 
> like to be able to perform the full range of calibrations on the 
> various modules. So, any advice on which multimeter would be a good 
> choice? (Someone mentioned extech instead of fluke because 
> the "higher resolution" was better for calibrating oscillators at 
> lower frequencies.) I'm willing to spend a few hundred dollars on 
one.
> 
> Next up on the parade of topics which yield highly opinionated 
> responses - a soldering iron. I have decided, perhaps foolishly, I 
> might be able to pull off a 1/5 or 2/5 difficulty kit without 
burning 
> the house down or irreparably damaging multiple digits. (Since I 
have 
> 2 eyes I figure I can live with the inevitable "poking out" of one 
of 
> them.) I want a quality soldering iron that will last but also 
don't 
> need one somebody who does this for a living would get. 
> Unfortunately, the Weller model everyone seems to like looks to 
have 

> been discontinued.
> 
> The rest of the tools needed to "venture forth" seem pretty 
> straightforward. I would prefer to get the soldering iron and 
> multimeter right the first time ;-)

My wife built a 1/5 MOTM-800 EG and she had never touched a soldering iron.
Yes, the EG does work. :) You can do it. :)  Personally, I use Fluke meters.
Not because there is anything wrong with the others, but my experience has
been they are bullet proof.  I have a typical 3.5 digit great for most
applications (model 77 no longer made I have had it so long).  I also picked
up a used 6 digit meter for my bench which I have enjoyed immensely for
matching resistors and precise work.  However, new they are in the
$1300-1500 range.  I found mine used in excellent condition for $275.
Larry


"klstay" <kevinstay@e...> wrote:
I have decided, perhaps foolishly, I might be able to pull off a 1/5 or 2/5
difficulty kit without burning the house down or irreparably damaging
multiple digits.

From: Mike Marsh <mmarsh@...>
 What makes is do-able is the simple fact that Paul has created the ultimate
kit.  Great instructions, everything you need, and really good explainations
of  the circuits.

A new Extech 5/6 digit handheld multimeter is only $229 at
Future-Active.  It has the highest frequency resolution I've seen at
that price.  Do you need this for building MOTM modules - well, probably
not.  Your ear is a fine tuned instrument when it comes to frequency
deltas.  For tuning VCOs you use a calibrated source such as MIDI-CV
converter, and then tune to octaves by ear.  

Now if you're using the meter to tune notes, such as VCOs driven from
analog sequencer stages, the meter becomes more critical.  More
inexpensive meters have lower accuracy than your MOTM VCO, typically 1
Hz or 0.1 Hz resolution and 1% or 0.1% accuracy.  Paul published some
tracking numbers showing at 800 Hz the MOTM-300 was within .03 Hertz of
perfect tracking.  You can translate this to say your meter would need
better than .03 Hertz resolution and better than .03/800 x 100% =
.00375% accuracy to measure this.  Now even my Extech isn't that
accurate, but it's close. To put it another way, a 0.1% accurate meter
is only guaranteed to measure from 799.2 to 800.8 Hz for that perfect
800 Hz signal.

Bottom line is, decide whether you need this accuracy in a meter and
then check the specks of any potential purchases.  For tuning a cheap
instrument tuner might serve you better.

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com


> Yes, the EG does work. :) You can do it. :)  Personally, I use Fluke
> meters.
> Not because there is anything wrong with the others, but my experience
has
> been they are bullet proof.  I have a typical 3.5 digit great for most
> applications (model 77 no longer made I have had it so long).  I also
> picked
> up a used 6 digit meter for my bench which I have enjoyed immensely
for

> matching resistors and precise work.  However, new they are in the
> $1300-1500 range.  I found mine used in excellent condition for $275.
> Larry
>

For which modules (excluding the new ones) is it crucial to have a 
multimeter?  I'm guessing the VCOs might be one.. any others?

It's true that a meter should just meet your needs, otherwise you are 
throwing away good module money.  I suppose if you don't know your needs in 
advance (and are rich) you can buy a very accurate meter.  Maybe Paul will 
say what accuracy is needed for the MOTM module tuning.

Some tuning procedures, like the 1V/oct calibrations, require not only an 
accurate frequency counter but also a calibrated 1 volt source.   So you 
first have to calibrate your voltage source.  Then you check for 1V/oct 
response in multiple octaves.  If you are twisting a multi-turn trimpot, 
you have to go back and forth over the best spot several times to get the 
closest setting.  I guess my point is that meter accuracy buys you only so 
much and the rest is careful procedure.  If your meter or your procedure 
(or maybe your ear) is off, the result will be off.  It all comes down to 
what sounds right to the ear.  I calibrate sine wave shapers by ear, even 
though I also use a scope to view the waveform.

Why not get a "cheap" meter to start with and if you really notice that the 
accuracy is not sufficient for your needs, then buy a better one.  It never 
hurts to have two meters, either.  Meters that cost $30 today are as good 
or better than what we paid $200 for twenty years ago.  I've been happy 
with my $30 Craftsman Model 82139.

-Richard Brewster

At 05:51 PM 8/29/03 -0500, John Loffink wrote:

>A new Extech 5/6 digit handheld multimeter is only $229 at
>Future-Active.  It has the highest frequency resolution I've seen at
>that price.  Do you need this for building MOTM modules - well, probably
>not.  Your ear is a fine tuned instrument when it comes to frequency
>deltas.  For tuning VCOs you use a calibrated source such as MIDI-CV
>converter, and then tune to octaves by ear.
>
>Now if you're using the meter to tune notes, such as VCOs driven from
>analog sequencer stages, the meter becomes more critical.  More
>inexpensive meters have lower accuracy than your MOTM VCO, typically 1
>Hz or 0.1 Hz resolution and 1% or 0.1% accuracy.  Paul published some
>tracking numbers showing at 800 Hz the MOTM-300 was within .03 Hertz of
>perfect tracking.  You can translate this to say your meter would need
>better than .03 Hertz resolution and better than .03/800 x 100% =
>.00375% accuracy to measure this.  Now even my Extech isn't that
>accurate, but it's close. To put it another way, a 0.1% accurate meter
>is only guaranteed to measure from 799.2 to 800.8 Hz for that perfect
>800 Hz signal.
>
>Bottom line is, decide whether you need this accuracy in a meter and
>then check the specks of any potential purchases.  For tuning a cheap
>instrument tuner might serve you better.
>
>John Loffink
>The Microtonal Synthesis Web Site
>http://www.microtonal-synthesis.com
>The Wavemakers Synthesizer Web Site
>http://www.wavemakers-synth.com

The relatively new Fluke 187 is a very impressive multimeter with a number of features that are audio related (dBm and dBV measurements) and has a wide-bandwidth frequency counter.

For soldering irons I like Pace.  I got an amazing deal on a new-in-box unit on eBay, which is where I buy most of my bench and test equipment.  I think it was a $300 iron that I paid $80 for.

Ivan