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'[EE] Making my own oscilloscope'
2011\02\18@115423 by V G

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part 1 769 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable)

Hey all,

I'm in desperate need of some sort of "oscilloscope" but don't really have
the money to buy one at the moment. So I decided to make one.

It's going to be a very simple, low speed oscilloscope.

* For the ADC, I'm planning to use the LTC1418:
http://www.linear.com/product/ltc1418 (5V, 14 bit, 200ksps, SPI, high
impedance analog input, 0-4.096V input), which means around 100KHz bandwidth
tops, which is more than I need for now.

* The input to the ADC will come from a high precision opamp, probably an
LTC1050: http://www.linear.com/product/LTC1050

Here's a basic overview of what I'm thinking (attached as well):
http://img340.imageshack.us/img340/5610/oscilloscope.png

What do you guys think?


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2011\02\18@120902 by Robert Young

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From: spam_OUTx.solarwind.xTakeThisOuTspamgmail.com
Date: Fri, 18 Feb 2011 11:54:08 -0500
Subject: [EE] Making my own oscilloscope What do you guys think?

2011\02\18@121937 by Olin Lathrop

face picon face
V G wrote:
> I'm in desperate need of some sort of "oscilloscope" but don't
> really have the money to buy one at the moment. So I decided to make
> one.
>
> It's going to be a very simple, low speed oscilloscope.

If that's all you want, you may be able to get by with a ordinary sound card
and some software.  I vaguely remember there is already software out there
to use a sound card as a scope.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\02\18@131015 by V G

picon face
On Fri, Feb 18, 2011 at 12:19 PM, Olin Lathrop <.....olin_piclistKILLspamspam@spam@embedinc.com>wrote:
>
> If that's all you want, you may be able to get by with a ordinary sound
> card
> and some software.  I vaguely remember there is already software out there
> to use a sound card as a scope
>

I want some level of isolation. Battery powered is good. Also, the soundcard
can only read AC signals as far as I know

2011\02\18@131154 by Michael Watterson

face picon face
On 18/02/2011 16:54, V G wrote:
> Hey all,
>
> I'm in desperate need of some sort of "oscilloscope" but don't really have
> the money to buy one at the moment. So I decided to make one.
>
> It's going to be a very simple, low speed oscilloscope.
>
> * For the ADC, I'm planning to use the LTC1418:
> http://www.linear.com/product/ltc1418 (5V, 14 bit, 200ksps, SPI, high
> impedance analog input, 0-4.096V input), which means around 100KHz bandwidth
> tops, which is more than I need for now.
>
> * The input to the ADC will come from a high precision opamp, probably an
> LTC1050: http://www.linear.com/product/LTC1050
>
> Here's a basic overview of what I'm thinking (attached as well):
> http://img340.imageshack.us/img340/5610/oscilloscope.png
>
> What do you guys think?
I think you couldn't make one for price of decent 2nd hand unless a free sound card driven scope with no calibrated attenuators and only about +/- 1V ppk range is OK.

2011\02\18@131247 by Michael Watterson

face picon face
On 18/02/2011 17:19, Olin Lathrop wrote:
> V G wrote:
>> I'm in desperate need of some sort of "oscilloscope" but don't
>> really have the money to buy one at the moment. So I decided to make
>> one.
>>
>> It's going to be a very simple, low speed oscilloscope.
> If that's all you want, you may be able to get by with a ordinary sound card
> and some software.  I vaguely remember there is already software out there
> to use a sound card as a scope.
>
>
> ********************************************************************
> Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
> (978) 742-9014.  Gold level PIC consultants since 2000.
Loads. Some quite good free with phase, vector scope, 2 ch scope and spectrum analyser

2011\02\18@135447 by Lyle Hazelwood

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On Fri, Feb 18, 2011 at 11:54 AM, V G <x.solarwind.xspamKILLspamgmail.com> wrote:
> Hey all,
>
> I'm in desperate need of some sort of "oscilloscope" but don't really have
> the money to buy one at the moment.

Just saw this yesterday.. Certainly cheap.
http://hackaday.com/2011/02/17/xprotolab-oscilloscope-and-xmega-development-board

2011\02\18@154008 by Chris McSweeny

picon face
On Fri, Feb 18, 2011 at 6:54 PM, Lyle Hazelwood <.....lylehazeKILLspamspam.....gmail.com> wrote:
> On Fri, Feb 18, 2011 at 11:54 AM, V G <EraseMEx.solarwind.xspam_OUTspamTakeThisOuTgmail.com> wrote:
>> Hey all,
>>
>> I'm in desperate need of some sort of "oscilloscope" but don't really have
>> the money to buy one at the moment.
>
> Just saw this yesterday.. Certainly cheap.
> http://hackaday.com/2011/02/17/xprotolab-oscilloscope-and-xmega-development-board/

Thanks - that is brilliant. All I need for most of the stuff I do, and
will save a lot of messing around with writing code for uCs to measure
stuff. Nice just for the very portable voltmeter feature. The only
problem appears to be getting hold of one - it seems to be very
popular!

Chri

2011\02\18@160548 by Brendan Gillatt

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On 18/02/11 16:54, V G wrote:
{Quote hidden}

Have a look at the DSO Nano oscilliscopes if you're on a budget:
http://www.seeedstudio.com/depot/dso-nano-v2-p-681.html?cPath=174

They are spec'ed up to 1MHz analog bandwidth (which is a lie--they
/sample/ at 1Msps so max 500KHz signal frequency at best).

At $90 you would be hard presed to completely develop from scratch
without spending more.

Brendan
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2011\02\18@173401 by Herbert Graf

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On Fri, 2011-02-18 at 21:05 +0000, Brendan Gillatt wrote:
> Have a look at the DSO Nano oscilliscopes if you're on a budget:
> www.seeedstudio.com/depot/dso-nano-v2-p-681.html?cPath=174
>
> They are spec'ed up to 1MHz analog bandwidth (which is a lie--they
> /sample/ at 1Msps so max 500KHz signal frequency at best).
>
> At $90 you would be hard presed to completely develop from scratch
> without spending more.

Frankly, if it samples at 1Msps then I wouldn't expect to use it for
anything more then 50-100kHz. Anything more and you can easily start
mistaking what's actually happening.

A good benchmark is the Tektronix baby scope we have in the lab samples
at 1Gsps, but specifies a bandwidth of 60MHz.

Still, if all you're doing is audio or a little above that it should
work well.

TTYL

2011\02\18@180740 by Brendan Gillatt

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On 18/02/11 22:33, Herbert Graf wrote:
{Quote hidden}

Yes you are correct; naturally, a real world signal will be
unintelligable when it is anywhere near the Nyquist frequency. I
probably shouldn't have mentioned 500KHz at all!

Still, 1Msps is an improvement over the OP's 200Ksps.

Brendan
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2011\02\18@184120 by Jesse Lackey

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I 2nd this suggestion.  If you are in desperate need, find $90 by selling old clothes on ebay and washing friends' cars and buy this.  I would not consider doing an oscilloscope design on a tight budget, timetable, and especially without a scope to help debug it.

Spend your energies designing the unusual, not the easily available for $100.  Leave re-inventing the wheel for when there is a really good reason (saving several $thousand, minimally) or you have nothing else you care to do.

My 2c.
J


Brendan Gillatt wrote:
{Quote hidden}

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2011\02\18@185320 by V G

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On Fri, Feb 18, 2011 at 6:41 PM, Jesse Lackey <jsl-mlspamspam_OUTcelestialaudio.com>wrote:

> I 2nd this suggestion.  If you are in desperate need, find $90 by
> selling old clothes on ebay and washing friends' cars and buy this.  I
> would not consider doing an oscilloscope design on a tight budget,
> timetable, and especially without a scope to help debug it.
>
> Spend your energies designing the unusual, not the easily available for
> $100.  Leave re-inventing the wheel for when there is a really good
> reason (saving several $thousand, minimally) or you have nothing else
> you care to do.
>
> My 2c.
>

Really? Wash cars? Because I have enough time to be washing cars, but not
enough to put together a simple ADC.

It's not that simple

2011\02\18@190249 by Jesse Lackey

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face
I think that you underestimate the design effort and debugging/testing needed to ensure decent analog performance in both bandwidth and DC accuracy, and without a scope to help you it gets even harder.

However, as the fortune cookie taped to my monitor says,
"Time is the coin of your life.  It is the only coin you have and only you can determine how it will be spent."

Just my 2c.  Good luck with your EE adventures, however you choose to spend your coin.

J

V G wrote:
{Quote hidden}

> It's not that simple

2011\02\19@121113 by V G

picon face
On Fri, Feb 18, 2011 at 7:02 PM, Jesse Lackey <KILLspamjsl-mlKILLspamspamcelestialaudio.com>wrote:

> I think that you underestimate the design effort and debugging/testing
> needed to ensure decent analog performance in both bandwidth and DC
> accuracy, and without a scope to help you it gets even harder.
>
> However, as the fortune cookie taped to my monitor says,
> "Time is the coin of your life.  It is the only coin you have and only
> you can determine how it will be spent."
>
> Just my 2c.  Good luck with your EE adventures, however you choose to
> spend your coin.


That "coin" is running out whether you're doing anything or not. It's a
trade off. What's the fastest way to do something? I don't know. But washing
cars is most certainly not it

2011\02\19@131823 by N. T.

picon face
V G wrote:
> I'm in desperate need of some sort of "oscilloscope" but don't really have
> the money to buy one at the moment. So I decided to make one.
>
> It's going to be a very simple, low speed oscilloscope.
>

There should be something of this kind for Android-based devices,
probably in the near future. Your data will be saved automatically as
Google docs

2011\02\19@133608 by Michael Watterson

face picon face
On 19/02/2011 18:18, N. T. wrote:
> V G wrote:
>> I'm in desperate need of some sort of "oscilloscope" but don't really have
>> the money to buy one at the moment. So I decided to make one.
>>
>> It's going to be a very simple, low speed oscilloscope.
>>
> There should be something of this kind for Android-based devices,
> probably in the near future. Your data will be saved automatically as
> Google docs.
That's depressing.

2011\02\19@152254 by N. T.

picon face
Michael Watterson wrote:
>>> I'm in desperate need of some sort of "oscilloscope" but don't really have
>>> the money to buy one at the moment. So I decided to make one.
>>>
>>> It's going to be a very simple, low speed oscilloscope.
>>>
>> There should be something of this kind for Android-based devices,
>> probably in the near future. Your data will be saved automatically as
>> Google docs.
> That's depressing.

Why? That ARM based devices have, if I am not mistaken, ADCs and GPIOs
on board. It's a matter of good analog front-end extension and ARM
code to catch the signal, digitize it and send it to the database.
Professional multimeters could be designed this way in the future. The
multi core 1GHz+ devices (not necessarily ARMs) can be quite capable
as pro EE devices, say, oscilloscopes. I'd rather say it's impressing,
not depressing

2011\02\19@152913 by Nathan House

picon face
Wouldn't a DIY oscilloscope with a microcontroller be limited to 0-5V

2011\02\19@160556 by Isaac Marino Bavaresco

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face
Em 19/2/2011 18:29, Nathan House escreveu:
> Wouldn't a DIY oscilloscope with a microcontroller be limited to 0-5V?

You would add an analog front-end to scale to input voltage up or  down
to best fit the vertical resolution, just as in any normal oscilloscope.

__________________________________________________
Fale com seus amigos  de graça com o novo Yahoo! Messenger http://br.messenger.yahoo.com

2011\02\19@164059 by V G

picon face
On Sat, Feb 19, 2011 at 3:29 PM, Nathan House <RemoveMEnathanpiclistTakeThisOuTspamgmail.com>wrote:

> Wouldn't a DIY oscilloscope with a microcontroller be limited to 0-5V?


Yeah, but if you look at the diagram, there are several modules in there to
take care of that.

* Input scaling resistors to downscale the voltage into range.

* Opamp gain setting resistors to scale up tiny voltages.

* Shunt to prevent over voltage into the AD

2011\02\19@184640 by RussellMc

face picon face
> >>> It's going to be a very simple, low speed oscilloscope.

> >> There should be something of this kind for Android-based devices,
> >> probably in the near future. Your data will be saved automatically as
> >> Google docs.

> > That's depressing.

> Why? That ARM based devices have, if I am not mistaken, ADCs and GPIOs
> ... I'd rather say it's impressing, not depressing.

You may get a better feel for the image that came to mind that caused
him to write that if you Gargafraffle various mixes of

Don't be evil.
To own all the world's data (aka store)
1984
George Orwell.
Waddya mean the network was down, how can the...
Standalone/ Self contained /
One may also, just possibly, invoke shadows of Godwin.

....

I imagine that he also finds it modestly impressive at a technical level.

Whatever.

       Russel

2011\02\20@012811 by doug metzler

picon face
I think you should go for it.  I'm excited to see a design that has a
wireless link to the computer.

When I got my first USB scope it was less than a week before I was convinced
that standalone scopes were a thing of the past - at least for the kind of
work I do.

So your first design might have some limitations, but that's what revisions
are for.

DougM

On Sat, Feb 19, 2011 at 3:46 PM, RussellMc <spamBeGoneapptechnzspamBeGonespamgmail.com> wrote:

{Quote hidden}

>

2011\02\20@020715 by Sean Breheny

face picon face
Nobody is suggesting that he not eventually try making his own scope.
However, it is foolish to think that one is going to lash up a scope
in a few days, with no budget and no additional scope to debug the
design. I tried doing this back when I was 18 years old and while I
did learn some things, it took me months and I did not succeed, mainly
because I lacked a scope to check my design.

Sean


On Sun, Feb 20, 2011 at 1:28 AM, doug metzler <TakeThisOuTdoug.metzlerEraseMEspamspam_OUTgmail.com> wrote:
{Quote hidden}

>> -

2011\02\20@161220 by doug metzler

picon face
Seems like you should be able to go down to the local technical school and
talk to the instructor about borrowing some time on a scope - they're not
that rare.

Or any local firm that does electronics work - they'll have several and I
would hope the techs there would be happy to help out.

DougM

On Sat, Feb 19, 2011 at 11:07 PM, Sean Breheny <shb7EraseMEspam.....cornell.edu> wrote:

{Quote hidden}

2011\02\20@170128 by Michael Watterson

face picon face
On 19/02/2011 23:46, RussellMc wrote:
> I imagine that he also finds it modestly impressive at a technical level.
>
> Whatever.
>
Indeed.
Of course sadly Orwell was writing about 1948

A second hand €80 dual channel Analogue scope will work calibrated to 15MHz or 25MHz. Display stuff usefully to 150MHz perhaps.
Have precision attenuators that would cost a fortune
Have wonderful timebase and triggering unavailable on any cheap USB digital Scope.

Build a scope if you want to learn and have fun. Get a second hand Analogue CRT model if you have only $90 and need a scope and the PC soundcard isn't good enough.
Google for FREE "visual Analyser 2010 NE-XT v2.4 or Sillanumsoft
Uses Soundcard(s)
Scope, Spectrum analyser, Vector scope,
signal generator(s), function Generator
phase meter
Frequency Meter
Filters etc..




Yes Smart phones are impressive. But I'd buy a phone as a phone primarily. It's amazing indeed what they fit in.
I shall write an article shortly partly from memory and partly research and experience of ARM from the 1987 Acorn User cover (I have original issue I bought at the time) to today's Quad Core + GPU ARM. and also Cortex Mx series for Embedded.

My son is debugging a Blackfin at the minute.

But decent test gear as test gear, that doesn't say where I am and what I'm doing.

Android/davik/Java is not a reliable platform for testgear.
Only specialist versions of Linux are real time in sense test gear needs to be.

Smart move RIM buying QNX.

2011\02\20@175836 by William \Chops\ Westfield

face picon face

On Feb 20, 2011, at 2:01 PM, Michael Watterson wrote:

> Get a second hand Analogue CRT model if you have only $90 and need a  
> scope and the PC soundcard isn't good enough.

And you have lots of room.  Old analog scopes were designed in an age  when real estate was a lot cheaper, and they fit in the average  college dorm or apartment like an SUV fits in a bike rack.

When I saw the TDS210 at Fry's (one of the relatively early "low  profile" digital scopes), it was the first time I knew that a personal  scope was in my future.  (But they're still pricey, even used...)

(I wonder how often the precision of a good scope is actually used, vs  simpler use as a "visualization tool.")

BillW

2011\02\20@210443 by Sean Breheny

face picon face
Not all "old" analog scopes are huge. The Tek 465/475 series is about
the same width as the TDS210 and about 2.5 times the depth. The later
Tek 2000 series (1980s vintage) are about the same size and
considerably lighter than the 475. You are probably thinking of the
Tek 7000 series which were never intended for general electronics work
but rather as fixed lab-type units capable of accepting lots of
different kinds of plug-in modules.

As for precision, most modern scopes are only 8 bit vertical
resolution. If you turn on averaging, you can often get about 2 or 3
more effective bits. The horizontal accuracy is pretty good,
especially with measure functions. However, at 8 bits vertical, their
amplitude measuring ability is not much better than a well-adjusted
analog scope. Some of the later analog scopes also have cursors with a
readout.

Sean


On Sun, Feb 20, 2011 at 5:58 PM, William "Chops" Westfield
<RemoveMEwestfwspam_OUTspamKILLspammac.com> wrote:
{Quote hidden}

>

2011\02\21@044708 by cdb

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face


:: 'm in desperate need of some sort of "oscilloscope" but don't
:: really have the money to buy one at the moment.

For Audio work only the Elektor Gameboy Oscilloscope isn't too bad. You need a Gameboy of course plus the add on FPGA cartridge.

Not sure if Elektor are still selling the module, though it may still be outside your price range. I tried to sell mine on Ebay, no one was interested. :(

Colin
--
cdb, RemoveMEcolinTakeThisOuTspamspambtech-online.co.uk on 21/02/2011
Web presence: http://www.btech-online.co.uk   Hosted by:  http://www.justhost.com.au

2011\02\21@180213 by IVP

face picon face
> I'm in desperate need of some sort of "oscilloscope" but don't really
> have the money to buy one at the moment. So I decided to make one

Of all the test gear I have, the one which I find tends to be of most help
debugging and solving problems is the logic analyser. At one time I had
just a cheap 6MHz scope, and realised very quickly that an analyser is
essential when working with micros. I built my first one based around a
68HC705 and SRAM. The next used a 20MHz 16F84, PLL and ex-
mobo fast cache RAM. Both of those uploaded to the PC via serial.
The current one is a 16-channel USB. Each has been invaluable in its
time, and a good spec analyser is not difficult to DIY if you have logic
chips doing all the donkey work

Jo

2011\02\21@181600 by Matt Callow

flavicon
face
On 22 February 2011 10:01, IVP <EraseMEjoecolquittspamspamspamBeGoneclear.net.nz> wrote:
>> I'm in desperate need of some sort of "oscilloscope" but don't really
>> have the money to buy one at the moment. So I decided to make one
>
> Of all the test gear I have, the one which I find tends to be of most help
> debugging and solving problems is the logic analyser. At one time I had
> just a cheap 6MHz scope, and realised very quickly that an analyser is
> essential when working with micros. I built my first one based around a
> 68HC705 and SRAM. The next used a 20MHz 16F84, PLL and ex-
> mobo fast cache RAM. Both of those uploaded to the PC via serial.
> The current one is a 16-channel USB. Each has been invaluable in its
> time, and a good spec analyser is not difficult to DIY if you have logic
> chips doing all the donkey work
>
> Joe

If you want a cheap logic analyser, take a look at
http://dangerousprototypes.com/open-logic-sniffer/

Mat

2011\02\22@064725 by KPL

picon face
>
> If you want a cheap logic analyser, take a look at
> http://dangerousprototypes.com/open-logic-sniffer/
>
> Matt
> --

It did not seem very valuable while there is no additional RAM
available for it. You are forced to use quite high sample rate to
catch up with fast PIC signals, but then there is much too short RAM
buffer.
Probably things have changed now, have not checked their updates since
I burned my sniffer board...

-- KP

2011\02\22@082937 by Michael Watterson

face picon face
On 21/02/2011 23:01, IVP wrote:
>> I'm in desperate need of some sort of "oscilloscope" but don't really
>> have the money to buy one at the moment. So I decided to make one
> Of all the test gear I have, the one which I find tends to be of most help
> debugging and solving problems is the logic analyser. At one time I had
> just a cheap 6MHz scope, and realised very quickly that an analyser is
> essential when working with micros. I built my first one based around a
> 68HC705 and SRAM. The next used a 20MHz 16F84, PLL and ex-
> mobo fast cache RAM. Both of those uploaded to the PC via serial.
> The current one is a 16-channel USB. Each has been invaluable in its
> time, and a good spec analyser is not difficult to DIY if you have logic
> chips doing all the donkey work
>
> Joe
A home made logic analyser is more sense than a scope. There is is software for Pickit2 and also for serial port handshake pins (not very many inputs!)

2011\02\22@141524 by Herbert Graf

picon face
On Sat, 2011-02-19 at 22:28 -0800, doug metzler wrote:
> I think you should go for it.  I'm excited to see a design that has a
> wireless link to the computer.
>
> When I got my first USB scope it was less than a week before I was convinced
> that standalone scopes were a thing of the past - at least for the kind of
> work I do.

Interesting, when I got my first USB scope it took me about a week
before I realized it was not even close to a substitute for the
standalone. I guess that's just a result of the kind of work I do! :)

TTYL

2011\02\22@154315 by doug metzler

picon face
I wonder if we got the same scope :-)

DougM


On Tue, Feb 22, 2011 at 11:15 AM, Herbert Graf <RemoveMEhkgrafKILLspamspamgmail.com> wrote:

{Quote hidden}

>

2011\02\22@172424 by Herbert Graf

picon face
On Tue, 2011-02-22 at 12:42 -0800, doug metzler wrote:
> I wonder if we got the same scope :-)
>
> DougM

Can't remember what it was, but my concerns were irrespective of brand.

For me the main issue was making adjustments. When I use a scope I'm
changing things alot, pressing buttons and turning knobs is MUCH more
convenient then using a mouse and turning "virtual" knobs.

I often adjust a scope without actually looking at the buttons, keeping
my eye on the screen, that's impossible when using a mouse and a GUI, I
found that very distracting.

I also had issue with the update rate, I found there was a noticeable
lag between what was being measured and what was displayed.

Thing is, it can be built in a tolerable way. The scopes I use at work
are basically PCs that are dedicated to custom scope hardware. They even
have keyboards and mice. The difference is they have the full control
panel, and a display optimized for refreshing the display as close to
real time as possible.

TTYL


2011\02\22@192203 by YES NOPE9

flavicon
face

> On Feb 22, 2011, at 3:24 PM, Herbert Graf wrote:
>
> On Tue, 2011-02-22 at 12:42 -0800, doug metzler wrote:
>> I wonder if we got the same scope :-)
>>
>> DougM
>
> Can't remember what it was, but my concerns were irrespective of brand.
>
> For me the main issue was making adjustments. When I use a scope I'm
> changing things alot, pressing buttons and turning knobs is MUCH more
> convenient then using a mouse and turning "virtual" knobs.
>
> I often adjust a scope without actually looking at the buttons, keeping
> my eye on the screen, that's impossible when using a mouse and a GUI, I
> found that very distracting.
>
> I also had issue with the update rate, I found there was a noticeable
> lag between what was being measured and what was displayed.

Would a USB scope be useful to you if it had a USB connected control panel ?
( with knobs and stuff )
gus in denver 99gus
>
> Thing is, it can be built in a tolerable way. The scopes I use at work
> are basically PCs that are dedicated to custom scope hardware. They even
> have keyboards and mice. The difference is they have the full control
> panel, and a display optimized for refreshing the display as close to
> real time as possible.
>
> TTYL
>

2011\02\23@064747 by Herbert Graf

picon face
On Tue, 2011-02-22 at 17:22 -0700, YES NOPE9 wrote:
> Would a USB scope be useful to you if it had a USB connected control panel ?
> ( with knobs and stuff )
> gus in denver 99gus

It would be better, but then you're going up in cost and approaching
basic standalone units.

You'd still most likely have the issue of display lag.

It all depends on how you use a scope, for many the USB scope idea is
fantastic, I only pull mine out when I have no other option.

TTYL

2011\02\23@124754 by doug metzler

picon face
I agree with the display lag problem - it's disconcerting for the display to
freeze while the USB channel is trying to re-fill the buffer when I change a
setting.

The USB control panel is an interesting idea but would require that you have
a spot for the control panel on your bench.  I like that I bring the scope
to the circuit and not the other way around.

An iPad app with a wireless connection to the device might be interesting,
Imagine if you could use the 2-finger separate (like enlarging pictures/web
pages) to change your vertical or horizontal resolution.  If we ever get
desktop touch screens then that could change everything.

DougM

On Wed, Feb 23, 2011 at 3:47 AM, Herbert Graf <hkgrafSTOPspamspamspam_OUTgmail.com> wrote:

{Quote hidden}

>

2011\02\23@141554 by Olin Lathrop

face picon face
doug metzler wrote:
> I agree with the display lag problem - it's disconcerting for the
> display to freeze while the USB channel is trying to re-fill the
> buffer when I change a setting.
>
> The USB control panel is an interesting idea but would require that
> you have a spot for the control panel on your bench.  I like that I
> bring the scope to the circuit and not the other way around.
>
> An iPad app with a wireless connection to the device might be
> interesting, Imagine if you could use the 2-finger separate (like
> enlarging pictures/web pages) to change your vertical or horizontal
> resolution.  If we ever get desktop touch screens then that could
> change everything.

This brings up a idea I've had in the back of my mind for a few years.

I've been thinking about making a cheap but usable scope by getting rid of
the monitor and having a front panel that is all capacitive sense switches.
The front panel could be a circuit board with the right paint, maybe even
just the silkscreen layer on it.

Instead of a monitor, it would have a SVGA output.  Everybody has a old SVGA
monitor or two lying around unused nowadays.  These cheaply give you way
more pixels than even high end scopes do, and full color.  No need for more
than 1024 x 768 pixels.  The top of the scope would be flat to make it easy
to perch the monitor on.  I'd also provide a convenience power socket on the
back of the scope so the whole thing only needed a single power outlet.

I'd have a few dedicated buttons (capsence areas, actually), and probably
two rows of soft button at the top of the board just below where the display
should be.  The bottom portion of the display would always show the current
function of these soft buttons.

If you want to get fancy, allow chaining multiple base units together to get
more channels on one display.  The units would know they are chained and
everything could still be controlled from the buttons only on the master.
For that matter, you could have separate add on units that had no buttons at
all that are only slaves.

Even if someone didn't have a old monitor they'd have to buy one, but 12"
SVGA compatible monitors are dirt cheap nowadays.  The price would still be
less than what it would cost to build in a display.

2011\02\23@153130 by Mark E. Skeels

flavicon
face
Only thing is the old monitor would be be bigger and bulkier than most scopes nowadays.

Take up a lot of bench space, would it not?

Make it work with an Android tablet, Olin.

Mark Skeels
Engineer
Competition Electronics, Inc.
TEL: 815-874-8001
FAX: 815-874-8181
http://www.competitionelectronics.com

On 2/23/2011 1:16 PM, Olin Lathrop wrote:
{Quote hidden}

2011\02\23@154331 by Herbert Graf

picon face
On Wed, 2011-02-23 at 09:46 -0800, doug metzler wrote:
> I agree with the display lag problem - it's disconcerting for the display to
> freeze while the USB channel is trying to re-fill the buffer when I change a
> setting.
>
> The USB control panel is an interesting idea but would require that you have
> a spot for the control panel on your bench.  I like that I bring the scope
> to the circuit and not the other way around.
>
> An iPad app with a wireless connection to the device might be interesting,
> Imagine if you could use the 2-finger separate (like enlarging pictures/web
> pages) to change your vertical or horizontal resolution.  If we ever get
> desktop touch screens then that could change everything.

To be frank, a touch screen would probably be WORSE then the mouse.

The whole point is tactile feedback without needing to look. While a
mouse has barely any useful tactic feedback, a touch screen has exactly
zero.

A long long time ago my brother purchased a really nice home theatre
receiver (Sony ES line). It had this amazing universal 2 way remote: it
would actually download the titles of all the CDs in his 200 disc CD
changer so you could choose the title on the remote and play it, and
other things like that.

>From a feature perspective it was incredible, years beyond anything of
it's time.

I used it for a couple days and never picked up that remote again. Why?
It was an LCD touch screen remote. The only buttons on it were volume,
everything else was the GUI on the screen. Change channels on the TV?
Look down at the screen on the remote and press the right button. Fast
forward the VCR? Look down at the remote and press the right button.
Skip a chapter on the DVD? Look down at the remote and press the right
button. It was the most frustrating "entertainment" experience Sony
could have come up with.

It sure looked good, and had a HUGE "wiz bang" factor, but usability?
There was zero there.

It was a classic example of the designers/engineers going for the most
feature rich thing them could come up without, and COMPLETELY ignore
whether it was actually usable. (oh, and the batteries lasted about a
week, not good in a remote).

TTYL

2011\02\23@161835 by Olin Lathrop

face picon face
Mark E. Skeels wrote:
> Only thing is the old monitor would be be bigger and bulkier than most
> scopes nowadays.
>
> Take up a lot of bench space, would it not?

Not really, since the monitor would be above the scope.  The footprint
wouldn't need to be any larger than even a small digital scope.  It would be
taller with a bigger display, but I think horizontal space is the biggest
issue in most cases.

This is to save cost.  Those who can afford a real scope will get a real
scope.  If you're on a budget, sitting a old 12" monitor atop a box no
bigger than a real scope would be a pretty good alternative I think.

> Make it work with an Android tablet, Olin.

That would defeat the design criteria and make it pointless.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\02\23@163204 by Joe Koberg

flavicon
face
On 2011-02-23 15:18, Olin Lathrop wrote:
> Mark E. Skeels wrote:
>> Only thing is the old monitor would be be bigger and bulkier than most
>> scopes nowadays.
>>
>> Take up a lot of bench space, would it not?
> Not really, since the monitor would be above the scope.  The footprint
> wouldn't need to be any larger than even a small digital scope.  It would be
> taller with a bigger display, but I think horizontal space is the biggest
> issue in most cases.

It's not as if LCD SVGA monitors are expensive or hard to find, either.  $25-$50 at the local state government surplus depot.

They might have a frame or two of lag, but I doubt it matters.  A CRT will have potentially higher contrast and more updates per second (Not uncommon to be able to push 120 frames/s into an SVGA monitor at an appropriate resolution).

Joe

2011\02\23@164217 by Joe Koberg

flavicon
face
On 2011-02-23 13:16, Olin Lathrop wrote:
> This brings up a idea I've had in the back of my mind for a few years.
>
>
> Instead of a monitor, it would have a SVGA output.  Everybody has a old SVGA
> monitor or two lying around unused nowadays.  These cheaply give you way

These guys did a bit of hacking inside the monitor to allow it to serve as an analog waveform (not raster) scope. They are driving VSYNC with a computer, but a PIC timer would likely work great while providing an adjustable timebase.   Perhaps omitting the sample storage is a pro or a con, depending on if you want simplicity vs DSO features.

    http://www.instructables.com/id/Make-an-oscilloscope-out-of-an-old-Crt-computer-mo/

I know real scope CRTs use electrostatic deflection, probably to avoid the inductance of deflection coils.  So who knows how well it would work at higher signal frequencies.

Joe

2011\02\23@172720 by Olin Lathrop

face picon face
Joe Koberg wrote:
> These guys did a bit of hacking inside the monitor to allow it to
> serve as an analog waveform (not raster) scope.

I didn't look at the link, but I did something like that in college 35 years
ago.  One of my friends had a old black and white TV with a busted tuner.
He also had a neon sign transformer we used to make the high voltage.  That
left the deflection coils all to us.  I rigged up a sawtooth generator and
driver for the horizontal coil and we used a regular audio amp to drive the
vertical coil.  We never set up any trigger circuit, but it was still fun to
see the waveforms on a really big screen.

Then we drove the horizontal and vertical coils from my roomate's stereo.
You could switch the amp to mono, and you got mostly a diagonal line as you
would expect.  Switching it to stereo you saw interesting displays.  I
remember that one particular John Denver song (I think it was "Calypso")
displayed nearly a circle when he sang a long note.  The left and right
pickups must have gotten the note just right at 90 degrees out of phase with
each other.

It was fun to mess around with, but making a real oscilloscope out of it
would have been a lot more work with not great results.  Due to the
inductance of the coils, it would have been limited to the audio range.  We
did this just for fun, and of course learned a bunch in the process.  We may
have created the first mindless automatically generated visually interesting
display to accompany music.  It was better than what Windows Media Player
shows today.

By the way, the guy who's TV it was and I think had the original idea may be
known to some of you as "Crash" on the Nerds Junkyard Wars team of a few
years back.  The TV oscilloscope thing was when we were both sophomores at
RPI.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\02\23@181952 by Michael Watterson

face picon face
On 23/02/2011 17:46, doug metzler wrote:
> If we ever get
> desktop touch screens then that could change everything.
>
We had light pens, then in 1970s they couldn't make a desk pen to control GUI so turned a Trackball upside down to make a mouse. Apple, Logitech and Microsoft copied this without understand what the Xerox guys really wanted.
I was designing touch screen gadget in 1989 with gestures based on that 1970s research.

We have had desktop touch screens for years. You can even buy for over 10 years or more retrofit touch for CRTS and LCDs.

They are exhausting to use. Your arm gets really tired.

There are scopes with touch screens only and ones with knobs and touch screens. The Ones with Knobs are preferred by everyone.

A Scope needs precision wide band flat amplifiers, good wide band attenuators, clever trigger HW & Software. It's a huge lot more to any more than a toy than an ADC and display. You can hook an  ADC to a Xilinx Spartan 3E and drive a VGA monitor direct from the FPGA pins. Probably a few MHz bandwidth ( > 50MHz Sampling) is possible.

Any kind of PIC based scope is hardly likely to be much more use than small notebook + sound inputs.

Capacitive touch is around as long as Resistive (a long long time!). It was of no interest to PDA / Gadget makers as they wanted handwriting. Capacitive Touch is like Finger painting. There are now some combo screens allowing light touch gestures and selections with finger (capacitive) and precision stylus/pen input also (resistive).

2011\02\23@192025 by V G

picon face
I must have a knack for creating really long threads

2011\02\23@194245 by Jesse Lackey

flavicon
face
Hi - just to add my 2c of course, something like this (cheap scope idea) with SVGA that can go to a LCD monitor would be real handy; DVI would be a nice feature but not required.

Being able to run the scope from a customizable app in windows over USB would be the killer selling point.  If it can programatically take measurements etc. for overnight testing of (whatever) or be used for small-run production testing (i.e. attach custom wire harness from scope inputs to test socket, run software on PC to exercise the (whatever) and take readings) that would be great.

Feature creep... but if it is relatively cheap ($hundreds) and makes testing 100 of something slightly complex easier and far more thorough, its worth it right there.

Cheers
J



Olin Lathrop wrote:
{Quote hidden}

2011\02\24@104517 by William Couture

face picon face
On Wed, Feb 23, 2011 at 5:27 PM, Olin Lathrop <spamBeGoneolin_piclistSTOPspamspamEraseMEembedinc.com> wrote:

> It was fun to mess around with, but making a real oscilloscope out of it
> would have been a lot more work with not great results.  Due to the
> inductance of the coils, it would have been limited to the audio range.  We
> did this just for fun, and of course learned a bunch in the process.  We may
> have created the first mindless automatically generated visually interesting
> display to accompany music.  It was better than what Windows Media Player
> shows today.
>
> By the way, the guy who's TV it was and I think had the original idea may be
> known to some of you as "Crash" on the Nerds Junkyard Wars team of a few
> years back.  The TV oscilloscope thing was when we were both sophomores at
> RPI.

>From Crash:

Yeah.  Olin and I used to hang around a lot together
at BARH (the residence hall he speaks of for sophmore
year).

We were bad news.  :-)  He was very proud that he made
_every_ dean's list... including the "on probation"
ones.

.... and I think I still have that old neon sign
transformer.  They never die.

We also came up with a way to do fast audio A/D
using CMOS switches and a bunch of resistors.  This
was after we blew up the Chem department's PDP-15
by wiring an R-2R ladder to the disk drive
controller's track servoing.

And then there were the laundry tickets.  That was
his schtick but he borrowed my micrometer to make it
happen.  Remind him of that.  I still have that
micrometer, too.  NSK made good stuff cheap then.

----

And, Davo remembers you, too.

Bill

-- Psst...  Hey, you... Buddy...  Want a kitten?  straycatblues.petfinder.org

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