[sdiy] Starting Point?
BrightBoy
jdec at mindspring.com
Mon Oct 12 04:49:47 CEST 2020
If you're going to buy a used scope, it's hard to beat the Tektronix 22xx line.
I know Paul Schreiber (MOTM) is rather fond of the 2230A.
I have a 2246 that I got at a pawn shop for $100
Cheers,
Jeff
-----Original Message-----
From: Pete Hartman
Sent: Oct 11, 2020 12:01 PM
To: synth-diy at synth-diy.org
Subject: Re: [sdiy] Starting Point?
I made do with a DSO quad for about 8 years. I used a community firmware so it had a bit more capability than the stock version (most frequently used was a frequency analyzer, after the main scope function). I only stepped up to a Rigol 1054 this year; didn't quite have the $500 for the Sigilent.
Biggest problems with the DSO were the tiny probe connections (which periodically broke on the probes) and toward the end, the battery life. But having a workable scope the size of a cellphone was nice.
I do understand the idea of the best tools you can afford, but you can go a long way with good enough tools.... I still haven't upgraded my iron from the sparkfun hakko knock off that I started with (though I replaced it with a duplicate once, and repaired it a second time).
I have an analog Tek scope too. I almost never used it because getting it lined up and in range was a pain. And it took up so much space.....
Pete
On Sun, Oct 11, 2020 at 10:38 AM Roman Sowa <modular at go2.pl> wrote:
Even $10k scope has offsets, that's what autocalibration is for.
Joy to use - probably not, as this is pocket size device. Can't
imagine knobs on such a thing. Either the size/portability or ease
of use. Trigger - exactly the basics of trigger in low end analog
scopes.
To have very good usable scope, there's at least $500 to spend.
Indeed for that price what you get is amazing, hard to imagine
what could anyone dream more for regular synth diy. If someone is
serious about entering into electronics DIY, then go and buy
Siglent SDS1000. But if not so sure yet, and the budget is tight,
there's no other choice than handheld toy scopes.
For a beginner it's bad idea to buy any old gear in bad shape.
After all, how can they fix it if they are begginers, right? And
if they have someone around more skilled to fix it, then the same
person can borrow their equipment, or tech them, or most of all
personally recommend suitable gear. I doubt any "skilled friend of
a beginner" would like to fix such a thing for a pack of beers.
And no, I haven't forgot how it was to be a beginner, I clearly
remember those days. Even clearer than what I was doing last year.
And I can't compare using toy scope to playing violin while
standing on one toe. That is more like sitting on a sofa and
playing PSP. Yes, I sometimes play with such scope in similar way
as other people waste their time twiddling their phones.
All I'm saying, if someone makes simple circuit on a breadboard,
and it doesn't work, it's end of story. A multimeter will not show
a fraction of what a scope can do. And maybe I'm patronizing now,
but I bet that first circuit made by total beginner might possibly
not work the first time. Without toy scope that means the circuit
goes to garbage, and disapointed beginner looses interest in
electronics and becomes fashion influencer or minecraft youtuber.
What a loss.
Now to be more specific, my one-line comments about some models:
DSO138 - unbelievably cheapest option, good for audio, terrible
use interface
DSO112A - touchscreen yeah! And sqr generator inlcuded. Much
better, but usable only in mid range of timebases
Fnirsi 2031 - ready to use in 2s! Good enough user interface,
actually can't remember what's so bad about it.
Fnirsi 1013 - if not one thing it would be the best handheld
scope ever created - it pretends to be low noise by some nasty
unpleasant trick. And it is way more outrageous than aliasing.
I'll share detailed findings if anyone's interested. But it's
slightly over $100 anyway.
There's so many more to try yet, but the above list presents
basicaly full range of them. Other popular variants like 150,
5012, 6100, 6020, 1C15, 1511 etc. always look similar (in
appearance, size and specs) to one of those listed here.
Roman
W dniu 2020-10-11 o 15:05,
sleepy_dog at gmx.de pisze:
I've seen some of those < 100 $ scope things that had DC
offsets, lacking coupling options, total garbage trigger
implementation and problems like that that make it not exactly a
joy to use, "entry level" or not.
Haven't looked at them for years. If you have an extensive
collection as you say you are more likely to have come across
ones that are decent - but is that a neutral view of the average
implementation you are most likely to get, or undue bias from
the ones you did like and use?
I guess one could make a list of "known usable" ones, but such a
list would become obsolete very quickly as things are today with
all this no name gear and endless copy of a copy of a product,
with the goal of further reducing the cost while being able to
sell the appearance of a known product for a better margin.
Sure, a old reputable-brand analog scope can be in bad shape,
totally decalibrated I guess - maybe in that regard it's also
risky to buy one as a beginner?
Although sometimes they throw those out for (almost) nothing :)
If one who got such a thing could get some friendly EE to look
at it if it's basically OK...
I'm not even saying specifically that alising thing really
affects anyone in reality, IDK, just wanted to thrown in a bunch
of possible examples of how one could add confusion or other
aspects that might deter a beginner.
Maybe you forgot how it can be as a total beginner because it's
so long ago for you. Stepping into a field with a lot of loose
ends in the mind and trying to make some connections and make
abstract principles you just read about become intuitive.
Gear doing funny things, it seemed to me, could disrupt that
process. (sure, at some point, observing unexpected things is
important to learn beyond the clear cut introductory textbook
examples - but in the very beginning?)
So the violin thing doesn't seem like a proper analogy.
You want people to learn violin - but standing on one toe
instead of sitting on a chair.
Bending a learning curve to your disadvantage is not virtuous.
The thing that is a virtue about putting in effort to learn
something is not the spending of the effort itself, or scrubbing
the floor with a toothbrush would be the most virtuous thing
ever.
AGAIN - maybe my examples of problems with toy gear weren't
good... but I'm not sure they are the only possible problems
with these wild east products whose essence seems to be
fluctuating all the time.
As you say, such gear are tools for thinkig humans - already the
good ones. Maybe bad gear is ramping up the difficulty level?
That's what I was trying to get at with maybe not the best
examples.
OKAY, and perhaps I also just find it hard to believe that some
< 100 $ thing of that class of instruments can be decent
enough.
Just a couple years ago a 500 $ scope was looked at with
suspicion, and I bought one due to lack of options ;) (and it
did have some issues)
And I don't think I'm quite the oldest fella on this list here -
but it still seems just like yesterday. Ok, maybe I'm starting
to get old :D
Sorry for the long and perhaps boring text.
I just really do like to sort out how my perceptions came to be
as they are and them not aligning with the basic sentiment put
forth by you.
I get it I'm only a lowly hobbyist, and worse, one that has
roughly a million other hobbies and just can't frickin stick to
one :D
- Steve
Roman Sowa wrote:
Yes, really.
Signal amplitude of interest is well covered. You don't need
500V/div in a scope. Analog front end is adequate to the scope
bandwidth which go up to some 30MHz in those toys. Maybe
missing those 1mV/div settings in some models, but who needs
that for entry level DIY? The old analog scopes were usually
5-20MHz and bandwidth was not the weakest pont anyway. First
100MHz analog scope I saw was big heavy and noisy Russian
machine in mid 90's.
Aliasing in digital scopes is a thing and anybody using it is
aware of that. It's mentioned everytime someone says
"oscilloscope". I think a newbie first learns about aliasing
before knowing what an oscilloscope is. It's like saying you
can't work with high voltage because it can shock you. There
is no scope that prevents aliasing, no such thing as antialias
filtering in any scope, including top range of top brands,
because it's limiting and useless. Just like there's no scope
with a button "show me what's wrong with this signal". A scope
is a tool for thinking human.
A violin will not play by itself either and if you don't know
how to play, it will only make terrible noises, even if it's
$1M Stradivari.
Roman
W dniu 2020-10-10 o 11:01, sleepy_dog at gmx.de pisze:
> small toy scopes for below $100. And frankly they are
better than big 50kg scopes I had in school
Really? Including the analog front end, signal amplitude it
can take, coupling options etc?
And those old clunky analog scopes in school certainly did
not fool you with aliasing due to improper filtering esp.
when sample rate drops on long time base with ridiculously
low k(!)points memory depth (like also "cheaper" *cough* Tek
DSOs just a couple years ago), making you see things that
aren't there.
Those below 100 bucks scopes also usually have a very low
sampling rate to start with, right?
(don't "need" so high frequencies in synth DIY? Well, the
*intended* frequencies that your DIY circuits *intentionally
oscillate* at may perhaps not need that... :D)
Sure, he can watch a video like below and then know about
that one thing.
It seems to me when entering a subject with a million
questionmarks, adding more confusing stuff one has to be
aware of might be disorienting.
https://www.youtube.com/watch?v=uWADu0aKk0w
- Steve
Roman Sowa wrote:
Totally agree.
What may not seem so obvious, there's a catch - when you
can afford all the fancy tools you dream of, then suddenly
your creativity drops down the floor. With crappy tools
you have to be more creative and think, imagine, explore,
experiment. For example soldering - you have to learn how
to solder anyhow, and cheap soldering iron is not
forgiving, so it will force you to think what you're doing
and be totally aware of what to do in certain situations.
I have bought my first temperature controlled station
about 20 years after I started soldering. Only because of
that I could appreciate it. In case you wonder, yest it's
possible to succesfully solder SMD with transformer
soldering gun.
The scope is essential, I think even more than
multimeter, but today you can buy small toy scopes for
below $100. And frankly they are better than big 50kg
scopes I had in school. I have quite a few of those toy
scopes, this is my small addiction, so if you want to ask
about specific model, I probably have that. Don't buy
"best scope you can afford", or "scope planned for the
future". Those times are over. Now there's new scope
coming every year, cheaper and better than others. After
2-3 years you'll know what to look for, and it will be
more GAS hitting than real measurement needs.
It is very unpopular point of view here, but I think
modern digital scopes are much better that vintage analog
Tek.
Roman
W dniu 2020-10-10 o 01:49,
Peter Pearson pisze:
While I agree that spending $1k will
definitely get you set up, we aren't all so lucky.
Especially when we're spending money made mowing lawns
or working minimum wage as a youngster. What I meant
was that a quality iron will really make the biggest
improvement. That plus an "it works fine" multimeter
and a working 20MHz oscilloscope used is almost all you
need (less parts but that's subjective) to do some
damage. Take the price point down from $1k to something
more like $200-$300 or less and that's attainable for a
lot of people.
Something like this:
https://www.youtube.com/watch?v=HicV3Z6XLFA
BUY USED!
You can work up to a $10k oscilloscope or whatever
once you need one.
On Fri, Oct 9, 2020 at
7:36 PM Benjamin Tremblay via Synth-diy <synth-diy at synth-diy.org>
wrote:
I learned this
stuff as a kid through trial, error, burned fingers,
and Radio Shack. I never had more than ten or so
dollars on hand, so no voltmeter, no breadboard, no
spools of wire. I remember building the basic 556
“Atari punk console” circuit and just thinking it made
horrible noises nobody would ever want to hear.
After building light-controlled oscillators for a
year, I started checking out books at Colorado State
University. The ancient books were the best: Musique
Concrète and this book written in Spanish from the
1940s showing how a film loop generating optical
pulses going into a modulator circuit could be what we
call a drum machine. My mother told me about the
Telharmonium in Worcester MA she read about in Yankee
Magazine. I built a Theremin using an oscillator and
an AM radio, and realized it would be easier to master
the violin than to get a melody out of a Theremin.
Then I found the 1970s books from UCLA on what we now
call West Coast Synthesis. When I got to the log
tables in the middle of the book I knew I couldn’t
follow it; if music was math, music was not for me.
It took a couple of years of futility to realize I had
to try again.
Paia was so inspirational, yet at the same time I felt
the kits were full of design compromises that left me
in the dark about best practices. (I remember testing
the Gnome after my brother put it together and we both
thought it was broken; but it was just the T filter
doing its crappy T filter thing.)
Then I was gifted a broken Paia Proteus when I was a
junior in high school. Fixing that beautiful machine
gave me a new appreciation for Paia.
Paia turned me onto Don Lancaster and Craig Anderton
(as editor of Electronic Musician).
After I got my hands on the books by Bryce Ward and
Barry Klein, I really wanted to do this stuff, but I
had no way to earn a living, and neither the math nor
the music.
How long does one have to live before you just start
doing what you love?
Benjamin Tremblay
> On Oct 9, 2020, at 6:53 PM, Benjamin Tremblay via
Synth-diy <Synth-diy at synth-diy.org>
wrote:
>
>
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