Low spec 'scope.

Post by Liz Tuddenham
The recent thread on high-end oscilloscopes has reminded me of a project
that I shelved some years ago and might be due for resurrection: I am
looking for a real-time display about 3" x 4" that can behave as an X-Y
oscilloscope with a bandwidth of about 100 Kc/s; a flat panel would be
ideal.
Currently I am using an actual X-Y oscillocsope to monitor the output
from a stereo gramophone cartridge, which allows me to check historic
discs for damage or faulty recording geometry. The tube is about 14"
long, which means it has to be a standalone shelf unit and I can't build
anything like it into portable equipment.
I've not come across anything like this, but I'm sure such things either
exist or can be made by adapting something that is readily available. I
have never been down the digital route, so anything that would need a
lot of programming from scratch will never get built.

How about this? https://tinyurl.com/39pkzb5v
I haven't used this Chinese kit myself but it's been around for quite
some time. The display is only 2.4" though. With an aspect ratio of 4:3,
that would be about 1.9x1.4.

Liz Tuddenham

2024-08-28 09:26:12 UTC

Post by Pimpom

That's the sort of thing, but it does need a 'Y' input and must start in
the correct mode on power-up, as the screen will be built into a piece
of equipment with no room for extra panel controls.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Jan Panteltje

2024-08-28 10:29:06 UTC

On a sunny day (Wed, 28 Aug 2024 08:39:25 +0100) it happened

This was an experiment:
https://panteltje.nl/panteltje/pic/scope_pic/
works for audio, has spectral display too,
can also send screendump as text file to Usenet.
Control via RS232 or some buttons if you can code.

Cost? Maybe the LCD is the most expensive part, 5 dollars?
Display has low resolution, so I did a shift right a couple of times to divide the output.
A better display will give better resolution.
There are plenty of single chip cheap digital scopes on ebay.
https://www.ebay.nl/itm/315279795435
have not tried that one :-)

Liz Tuddenham

2024-08-28 12:41:10 UTC

Post by Jan Panteltje
On a sunny day (Wed, 28 Aug 2024 08:39:25 +0100) it happened

Post by Liz Tuddenham
The recent thread on high-end oscilloscopes has reminded me of a project
that I shelved some years ago and might be due for resurrection: I am
looking for a real-time display about 3" x 4" that can behave as an X-Y
oscilloscope with a bandwidth of about 100 Kc/s; a flat panel would be
ideal.
Currently I am using an actual X-Y oscillocsope to monitor the output
from a stereo gramophone cartridge, which allows me to check historic
discs for damage or faulty recording geometry. The tube is about 14"
long, which means it has to be a standalone shelf unit and I can't build
anything like it into portable equipment.
I've not come across anything like this, but I'm sure such things either
exist or can be made by adapting something that is readily available. I
have never been down the digital route, so anything that would need a lot
of programming from scratch will never get built.

https://panteltje.nl/panteltje/pic/scope_pic/
works for audio, has spectral display too,
can also send screendump as text file to Usenet.
Control via RS232 or some buttons if you can code.

Thanks very much for that. It has most of the reatures I need and the
sampling rate is just about adequate. It 'remembers' its last settings,
which is essential for this application.

I have coded in the past but it was a most frustrating exercise and
something I would like to avoid if possible. Also, I don't have any way
of connecting to the chip and uploading the code.

Post by Jan Panteltje
Cost? Maybe the LCD is the most expensive part, 5 dollars?

Very reasonable

Post by Jan Panteltje
Display has low resolution, so I did a shift right a couple of times to
divide the output. A better display will give better resolution.

The detail is extemenly important in this application - the minimum
resolution being 200 dpi.

Post by Jan Panteltje
There are plenty of single chip cheap digital scopes on ebay.
https://www.ebay.nl/itm/315279795435
have not tried that one :-)

I'll have to work through them and see which ones can be used as X-Y
scopes, with good enough resolution and the ability to start fully
functional from power-up.

Failing that, I have an oscilloscope tube and driver chassis, so I could
mount it horizontally in the bottom of the box with a 45-degree mirror,
so I can look down on it through a hole in the horizontal control panel.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Jan Panteltje

2024-08-28 15:12:02 UTC

On a sunny day (Wed, 28 Aug 2024 13:41:10 +0100) it happened

Post by Jan Panteltje
On a sunny day (Wed, 28 Aug 2024 08:39:25 +0100) it happened

Post by Liz Tuddenham
The recent thread on high-end oscilloscopes has reminded me of a project
that I shelved some years ago and might be due for resurrection: I am
looking for a real-time display about 3" x 4" that can behave as an X-Y
oscilloscope with a bandwidth of about 100 Kc/s; a flat panel would be
ideal.
Currently I am using an actual X-Y oscillocsope to monitor the output
from a stereo gramophone cartridge, which allows me to check historic
discs for damage or faulty recording geometry. The tube is about 14"
long, which means it has to be a standalone shelf unit and I can't build
anything like it into portable equipment.
I've not come across anything like this, but I'm sure such things either
exist or can be made by adapting something that is readily available. I
have never been down the digital route, so anything that would need a lot
of programming from scratch will never get built.

https://panteltje.nl/panteltje/pic/scope_pic/
works for audio, has spectral display too,
can also send screendump as text file to Usenet.
Control via RS232 or some buttons if you can code.

Thanks very much for that. It has most of the reatures I need and the
sampling rate is just about adequate. It 'remembers' its last settings,
which is essential for this application.
I have coded in the past but it was a most frustrating exercise and
something I would like to avoid if possible. Also, I don't have any way
of connecting to the chip and uploading the code.

Post by Jan Panteltje
Cost? Maybe the LCD is the most expensive part, 5 dollars?

Very reasonable

Post by Jan Panteltje
Display has low resolution, so I did a shift right a couple of times to
divide the output. A better display will give better resolution.

The detail is extemenly important in this application - the minimum
resolution being 200 dpi.

Post by Jan Panteltje
There are plenty of single chip cheap digital scopes on ebay.
https://www.ebay.nl/itm/315279795435
have not tried that one :-)

I'll have to work through them and see which ones can be used as X-Y
scopes, with good enough resolution and the ability to start fully
functional from power-up.
Failing that, I have an oscilloscope tube and driver chassis, so I could
mount it horizontally in the bottom of the box with a 45-degree mirror,
so I can look down on it through a hole in the horizontal control panel.

I have designed and build several scopes with CRTs in the past,
first one used a DG7-32 CRT:
https://www.radiomuseum.org/tubes/tube_dg7-32.html
Actually the first one was an old TV CRT, much bigger, with magnetic deflection and a car ignition coil as HV generator
connected to the output of an audio amp with EL84, I made the amp oscillate at a few kHz (feedback to input) to drive that ignition coil.
stereo tube amp for H and V.
It is simple to make some 500V HV for for example a small CRT or GM tube:
https://panteltje.nl/panteltje/pic/gm_pic/
this one uses a simple 10:1 audio trasformer in reverse as flyback step-up:
https://panteltje.nl/panteltje/pic/gm_pic2/
Microchip PICs are great, have build in PWM generator, ADCs, EEPROM, voltage reference, what not.

The fasted analog scope I build was 300 MHz with an East German CRT, circuit was from Tek.
Transistor amplifers for deflection with BFY95 IIRC.

I still use my old Trio analog scope up until these days, works up to about 20 MHz (10 MHz officially).
for anything more RF I use RTL_SDR sticks and the spectrum analyzer I wrote:
https://panteltje.nl/panteltje/xpsa/index.html

If you have analog video and an x,y scope with intensity input:
https://panteltje.nl/panteltje/scope_tv/index.html
TV!

Martin Brown

2024-08-28 14:47:59 UTC

I think that Daqarta software can probably do about what you want using
the PC stereo soundcard to digitise X & Y. 100kHz bandwidth might be
pushing it but it should be fine for audio up to 20kHz.

https://www.daqarta.com/dw_scope.htm

https://www.daqarta.com/dw_0o0j.htm

Post by Liz Tuddenham
I've not come across anything like this, but I'm sure such things either
exist or can be made by adapting something that is readily available. I
have never been down the digital route, so anything that would need a
lot of programming from scratch will never get built.

I have used it for various demos. The spectrogram is handy too. Even if
you decide it isn't for you the free signal generator continues to work.

--
Martin Brown

Don Y

2024-08-28 15:32:46 UTC

I think that Daqarta software can probably do about what you want using the PC
stereo soundcard to digitise X & Y. 100kHz bandwidth might be pushing it but it
should be fine for audio up to 20kHz.

Does it *simultaneously* sample each channel? Or, toggle between them?

The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

Martin Brown

2024-08-28 16:05:47 UTC

I think that Daqarta software can probably do about what you want
using the PC stereo soundcard to digitise X & Y. 100kHz bandwidth
might be pushing it but it should be fine for audio up to 20kHz.

Does it *simultaneously* sample each channel? Or, toggle between them?

I have never looked hard enough or at a high enough frequency to tell
the difference. Audio demo's work best around 440Hz orchestral A which
most people can hear well. Waveform shapes and sounds are fun demos.

The guy knows what he is doing so I expect it is simultaneous sampling
of the waveforms to within a few memory cycles. Skew only becoming a
problem at very high frequencies. It is cute there is a free trial
period and you get to keep the (audio) waveform generator.

There is something similar for Android tablet/phones too but I don't
think that one does X-Y Lissajous figures (I could be wrong about that).
The waterfall spectrograph is quite a handy toy to have on your phone...

The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

It is a neat piece of software. Every now and then AV codes take against
it because it does do a bit of rather low level IO access (obviously).

--
Martin Brown

Don Y

2024-08-28 20:05:44 UTC

I think that Daqarta software can probably do about what you want using the
PC stereo soundcard to digitise X & Y. 100kHz bandwidth might be pushing it
but it should be fine for audio up to 20kHz.

Does it *simultaneously* sample each channel? Or, toggle between them?

I have never looked hard enough or at a high enough frequency to tell the
difference.

The OP would have to consider whether or not that would be significant
to their needs. I.e., a *real* 'scope would be driving the X&Y deflection
amplifiers simultaneously. No idea how the anomalies sought would
manifest...

Audio demo's work best around 440Hz orchestral A which most people
can hear well. Waveform shapes and sounds are fun demos.
The guy knows what he is doing so I expect it is simultaneous sampling of the
waveforms to within a few memory cycles. Skew only becoming a problem at very
high frequencies. It is cute there is a free trial period and you get to keep
the (audio) waveform generator.

But, wouldn't that depend on the *hardware's* capabilities?
I've not looked at the details of a sound card since the PAS-16 (!)
so have no idea what the current "standards" dictate. Now, I only
use sound cards to play music...

There is something similar for Android tablet/phones too but I don't think that
one does X-Y Lissajous figures (I could be wrong about that). The waterfall
spectrograph is quite a handy toy to have on your phone...

The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

It is a neat piece of software. Every now and then AV codes take against it
because it does do a bit of rather low level IO access (obviously).

Jasen Betts

2024-08-29 08:57:27 UTC

I think that Daqarta software can probably do about what you want using the PC
stereo soundcard to digitise X & Y. 100kHz bandwidth might be pushing it but it
should be fine for audio up to 20kHz.

or any other sound card scope software,

Post by Don Y
Does it *simultaneously* sample each channel? Or, toggle between them?

It makes an audio recording using commodity PC sound hardware.
https://www.ti.com/product/PCM2900C has 2 ADC channels

Post by Don Y
The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

It's starting to feel like raspberry pi + LCD display + usb sound card.

--
Jasen.
🇺🇦 Слава Україні

Liz Tuddenham

2024-08-29 09:43:29 UTC

I think that Daqarta software can probably do about what you want using
the PC stereo soundcard to digitise X & Y. 100kHz bandwidth might be
pushing it but it should be fine for audio up to 20kHz.

or any other sound card scope software,

Post by Don Y
Does it *simultaneously* sample each channel? Or, toggle between them?

It makes an audio recording using commodity PC sound hardware.
https://www.ti.com/product/PCM2900C has 2 ADC channels

Post by Don Y
The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

It's starting to feel like raspberry pi + LCD display + usb sound card.

The first bit sounds OK apart from the programming. This is a
standalone piece of analogue equipment, so there is no computer, no USB
and no sound card (nor any possibility of them).

If the Raspberry Pi could be made to fire itself up without any
intervention and accept two analogue inputs, that would work. (...but
someone would have to program it for me, or at least lead me through how
to program it.) The 100Kc/s requirement isn't just fanciful
over-specification; this thing works on the signals that are well
outside the audio band and the 'scope needs to display them clearly,
despite all the audio clutter. The H.F. signals are higher amplitude
than the audio but are in the nature of pulses and occur infrequently.
(The analogue scope has to be Z modulated from rate-of-change to
emphasise the pulses and avoid screen burn, but this wouldn't be a
problem with an LCD display.)

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Jan Panteltje

2024-08-29 10:36:58 UTC

On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened

Post by Liz Tuddenham
If the Raspberry Pi could be made to fire itself up without any

AFAIK Raspi has no ADC input.
You will have to connect an ADC to the GPIO.

Post by Liz Tuddenham
intervention and accept two analogue inputs, that would work. (...but
someone would have to program it for me, or at least lead me through how
to program it.) The 100Kc/s requirement isn't just fanciful
over-specification; this thing works on the signals that are well
outside the audio band and the 'scope needs to display them clearly,
despite all the audio clutter. The H.F. signals are higher amplitude
than the audio but are in the nature of pulses and occur infrequently.
(The analogue scope has to be Z modulated from rate-of-change to
emphasise the pulses and avoid screen burn, but this wouldn't be a
problem with an LCD display.)

1 channel kit: < 7 US dollars:
https://www.ebay.com/itm/295219906968
I cannot even buy the parts here for that price.
LCD 320x240 enough?

Fast CD4053 or something CMOS switch makes 2 channels?
Trigger channel select from a CD4073 flopflop after each scan?
the possibilitiies are endless

Knowing programming is almost a requirement these days (since the seventies) in electronics.

Liz Tuddenham

2024-08-29 11:58:10 UTC

Post by Jan Panteltje
On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened

Post by Liz Tuddenham
If the Raspberry Pi could be made to fire itself up without any

AFAIK Raspi has no ADC input.
You will have to connect an ADC to the GPIO.

https://www.ebay.com/itm/295219906968
I cannot even buy the parts here for that price.
LCD 320x240 enough?

That would correspond to a screen 1.6" x 1.2" at 200 dpi, which would be
a bit too small. I would regard 3" x 4" to be the optimum size. and 600
x 800 pixels to be the absolute minimum. There is no need for colour.

Post by Jan Panteltje
Fast CD4053 or something CMOS switch makes 2 channels?
Trigger channel select from a CD4073 flopflop after each scan?
the possibilitiies are endless

I'm not trying to display 2 channels on 1. I need an X-Y display so
that I can see the angle of contact of a stereo stylus with the
roughness of the groove wall and the pattern it traces as it plays the
modulation.

Post by Jan Panteltje
Knowing programming is almost a requirement these days (since the seventies) in electronics.

I have programmed in Z80 machine code, Algol, Basic, Applescript, PHP
and HTML, but have only used the last two recently. I also don't have
any programming tools as all my designs are analogue.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Jan Panteltje

2024-08-29 12:30:44 UTC

On a sunny day (Thu, 29 Aug 2024 12:58:10 +0100) it happened

Post by Jan Panteltje
On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened

Post by Liz Tuddenham
If the Raspberry Pi could be made to fire itself up without any

AFAIK Raspi has no ADC input.
You will have to connect an ADC to the GPIO.

https://www.ebay.com/itm/295219906968
I cannot even buy the parts here for that price.
LCD 320x240 enough?

Post by Jan Panteltje
Fast CD4053 or something CMOS switch makes 2 channels?
Trigger channel select from a CD4073 flopflop after each scan?
the possibilitiies are endless

Interesting
that is basically the channel separation?
Bias a normal needle type DC meter in the middle, mount it upside down
-------
\
\

and add rectified DC between left and right as bias?
More sound on left channel will move one way, more on right channel the other way.
Maybe not fast enough,...
Maybe just a phase comparator left/right and lowpass would do?
For some music it will be ;-)
Else get a cheap CRT?
https://www.ebay.com/b/oscilloscope-tube/bn_7024937658

Post by Jan Panteltje
Knowing programming is almost a requirement these days (since the

seventies) in electronics.
I have programmed in Z80 machine code, Algol, Basic, Applescript, PHP
and HTML, but have only used the last two recently. I also don't have
any programming tools as all my designs are analogue.

Anyways, there is a lot to play with...
I build my own PIC programmer... and wrote some software for it:
https://panteltje.nl/panteltje/pic/jppp18/index.html
https://panteltje.nl/panteltje/raspberry_pi_noppp/
PIC asm is not that hard...
One builds up libraries over time.

Liz Tuddenham

2024-08-29 14:39:00 UTC

Post by Jan Panteltje
On a sunny day (Thu, 29 Aug 2024 12:58:10 +0100) it happened

Post by Jan Panteltje
On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened

Post by Liz Tuddenham
If the Raspberry Pi could be made to fire itself up without any

AFAIK Raspi has no ADC input.
You will have to connect an ADC to the GPIO.

https://www.ebay.com/itm/295219906968
I cannot even buy the parts here for that price.
LCD 320x240 enough?

Post by Jan Panteltje
Fast CD4053 or something CMOS switch makes 2 channels?
Trigger channel select from a CD4073 flopflop after each scan?
the possibilitiies are endless

Interesting
that is basically the channel separation?

Not really, I need to know the instantaneous vector direction of the
stylus movement. On some 'Mono' recordings it can actually be moving in
a circle (the groove modulation is helical).

~~~~~~ Detailed technical information ~~~~~
This is caused by the cutting face of the recording cutter not being at
right angles to the direction of the groove (sometimes done deliberately
to throw the swarf clear), which results in the modulations on the two
groove walls being out of step with each other. When played with an
elliptical stylus tip, the phase difference generates a vertical
component which muddies the mono sound and plays hell with a declicker.
Twisting the cartridge about a vertical axis will displace the contact
points of the stylus on the groove wall and restore the sound quality
The amount of twist needed will depend on the amount and direction of
misaligment of the cutter, the groove wall angle and the size of stylus
used for playback. The pattern on the X-Y 'scope gives me valuable
information about this effect and enables me to optimaise the playback
angles without a lot of trial and error.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When playing 'shellac' records (which contain a lot of abrasive) the
roughness on one groove wall displaces the stylus at an angle up and
down the slope of the opposite groove wall. On an X-Y display, without
any modulation this looks like a letter 'X' but the angles of the two
arms of the 'X' may not be at 45 degrees.and may be unequal or even
change as the record revolves. I am dealing with material that may have
been badly recorded and will almost certainly have been damaged by poor
storage and massive playback devices (with heavy resonances). The
'scope is there to enable me to identify and correct as many of the
defects as possible.

Post by Jan Panteltje
Else get a cheap CRT?
https://www.ebay.com/b/oscilloscope-tube/bn_7024937658

There seem to be quite a few to choose from - and I have a couple
complete with their chassis in the attic. It looks as though I am going
to be short of space in the equipment I am designing, so perhaps the
oscilloscope will have to go as a separate item anyway.

Post by Jan Panteltje

Post by Jan Panteltje
Knowing programming is almost a requirement these days (since the

Anyways, there is a lot to play with...
https://panteltje.nl/panteltje/pic/jppp18/index.html
https://panteltje.nl/panteltje/raspberry_pi_noppp/
PIC asm is not that hard...
One builds up libraries over time.

That's what a friend keeps telling me. He advocates even the simplest
jobs being done with a microprocessor - but then he never seems to
produce anything that works. At least yours appear to be built and
working.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Jan Panteltje

2024-08-29 15:59:03 UTC

On a sunny day (Thu, 29 Aug 2024 15:39:00 +0100) it happened

Post by Jan Panteltje
On a sunny day (Thu, 29 Aug 2024 12:58:10 +0100) it happened

Post by Jan Panteltje
On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened

Post by Liz Tuddenham
If the Raspberry Pi could be made to fire itself up without any

AFAIK Raspi has no ADC input.
You will have to connect an ADC to the GPIO.

https://www.ebay.com/itm/295219906968
I cannot even buy the parts here for that price.
LCD 320x240 enough?

Post by Jan Panteltje
Fast CD4053 or something CMOS switch makes 2 channels?
Trigger channel select from a CD4073 flopflop after each scan?
the possibilitiies are endless

Interesting
that is basically the channel separation?

Not really, I need to know the instantaneous vector direction of the
stylus movement. On some 'Mono' recordings it can actually be moving in
a circle (the groove modulation is helical).

Ah, never too old to learn I am :-)

Post by Liz Tuddenham
~~~~~~ Detailed technical information ~~~~~
This is caused by the cutting face of the recording cutter not being at
right angles to the direction of the groove (sometimes done deliberately
to throw the swarf clear), which results in the modulations on the two
groove walls being out of step with each other. When played with an
elliptical stylus tip, the phase difference generates a vertical
component which muddies the mono sound and plays hell with a declicker.
Twisting the cartridge about a vertical axis will displace the contact
points of the stylus on the groove wall and restore the sound quality
The amount of twist needed will depend on the amount and direction of
misaligment of the cutter, the groove wall angle and the size of stylus
used for playback. The pattern on the X-Y 'scope gives me valuable
information about this effect and enables me to optimaise the playback
angles without a lot of trial and error.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Some years ago I was reading about an optical record player:
https://en.wikipedia.org/wiki/Laser_turntable
The camera based version seems interesting...
I had a Garrard record player with a Shure stereo element for many years
we would sit im my room at night and play records.... smoke...good stereo amp
and Philips 3 way speakers....

Later gave it all away, donated it.. including all the records
Now I got most of the music back as mp3 from the web from various sources.
Then came video...
Have a box with thousand burned CDs, DVDs, Blurays, what not,
plus some real CDs in boxes.
Loading Image...

Then came terabyte hardisks... 3 4 TB disks in use, 2 1 TB...
Music just a click away.
https://panteltje.nl/panteltje/newsflex/download.html#xmpl
Loading Image...

Loading Image...

In Linux 'updatedb' makes a list of everything on your system
'locate .mp3' will then find all mp3 etc
and in xmpl you can select some, make playlists etc..
I have an audio equalizer too
Loading Image...

latest xpsa spectrum analyzer also has FM stereo decoding...
Loading Image...

Big stage amplifier here, big boxes...
Playing Fazley keyboard every day... Still learning
https://www.bax-shop.nl/keyboards/fazley-fkb-120-keyboard
cannot make something like that for 110 dollars! No idea how they can make that. has decent speakers too.

PLayed trumpet in the sixties, guitar in the seventies...
The Fazley keyboard allows me to practice without freaking anybody out (using headphones) when I make mistakes...
Plenty of good old audio tracks can be heard and recorded from Astra satellite.
No idea if they got it from tape or vinyl
I still have some old audio cassettes... and a casette player.

Post by Liz Tuddenham
When playing 'shellac' records (which contain a lot of abrasive) the
roughness on one groove wall displaces the stylus at an angle up and
down the slope of the opposite groove wall. On an X-Y display, without
any modulation this looks like a letter 'X' but the angles of the two
arms of the 'X' may not be at 45 degrees.and may be unequal or even
change as the record revolves. I am dealing with material that may have
been badly recorded and will almost certainly have been damaged by poor
storage and massive playback devices (with heavy resonances). The
'scope is there to enable me to identify and correct as many of the
defects as possible.

Post by Jan Panteltje
Else get a cheap CRT?
https://www.ebay.com/b/oscilloscope-tube/bn_7024937658

Post by Jan Panteltje

Post by Jan Panteltje
Knowing programming is almost a requirement these days (since the

Yep the intention is to make things I want to use :-)

Martin Brown

2024-08-29 11:31:45 UTC

Post by Liz Tuddenham
The recent thread on high-end oscilloscopes has reminded me of a project
that I shelved some years ago and might be due for resurrection:Â I am
looking for a real-time display about 3" x 4" that can behave as an X-Y
oscilloscope with a bandwidth of about 100 Kc/s; a flat panel would be
ideal.
Currently I am using an actual X-Y oscillocsope to monitor the output
from a stereo gramophone cartridge, which allows me to check historic
discs for damage or faulty recording geometry.Â The tube is about 14"
long, which means it has to be a standalone shelf unit and I can't build
anything like it into portable equipment.

I think that Daqarta software can probably do about what you want using
the PC stereo soundcard to digitise X & Y. 100kHz bandwidth might be
pushing it but it should be fine for audio up to 20kHz.

or any other sound card scope software,

Post by Don Y
Does it *simultaneously* sample each channel? Or, toggle between them?

It makes an audio recording using commodity PC sound hardware.
https://www.ti.com/product/PCM2900C has 2 ADC channels

Post by Don Y
The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

It's starting to feel like raspberry pi + LCD display + usb sound card.

The first bit sounds OK apart from the programming. This is a
standalone piece of analogue equipment, so there is no computer, no USB
and no sound card (nor any possibility of them).
If the Raspberry Pi could be made to fire itself up without any
intervention and accept two analogue inputs, that would work. (...but
someone would have to program it for me, or at least lead me through how
to program it.) The 100Kc/s requirement isn't just fanciful
over-specification; this thing works on the signals that are well
outside the audio band and the 'scope needs to display them clearly,
despite all the audio clutter. The H.F. signals are higher amplitude
than the audio but are in the nature of pulses and occur infrequently.
(The analogue scope has to be Z modulated from rate-of-change to
emphasise the pulses and avoid screen burn, but this wouldn't be a
problem with an LCD display.)

Something like this on eBay might be what you want then:

https://www.ebay.co.uk/itm/275987222657

10MHz b/w (optimistic but probably better than 2Mhz) X-Y option.

I was assuming every engineer had a spare PC (or ten) lying around.

--
Martin Brown

Liz Tuddenham

2024-08-29 12:10:42 UTC

On 28/08/2024 08:39, Liz Tuddenham wrote: > The recent thread on
high-end oscilloscopes has reminded me of a project > that I shelved
some years ago and might be due for resurrection:Â I am > looking
for a real-time display about 3" x 4" that can behave as an X-Y >
oscilloscope with a bandwidth of about 100 Kc/s; a flat panel would be

Post by Liz Tuddenham
ideal.
Currently I am using an actual X-Y oscillocsope to monitor the output
from a stereo gramophone cartridge, which allows me to check historic
discs for damage or faulty recording geometry.Â The tube is about 14"
long, which means it has to be a standalone shelf unit and I can't build
anything like it into portable equipment.

I think that Daqarta software can probably do about what you want using
the PC stereo soundcard to digitise X & Y. 100kHz bandwidth might be
pushing it but it should be fine for audio up to 20kHz.

or any other sound card scope software,

Post by Don Y
Does it *simultaneously* sample each channel? Or, toggle between them?

It makes an audio recording using commodity PC sound hardware.
https://www.ti.com/product/PCM2900C has 2 ADC channels

Post by Don Y
The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

It's starting to feel like raspberry pi + LCD display + usb sound card.

The first bit sounds OK apart from the programming. This is a
standalone piece of analogue equipment, so there is no computer, no USB
and no sound card (nor any possibility of them).
If the Raspberry Pi could be made to fire itself up without any
intervention and accept two analogue inputs, that would work. (...but
someone would have to program it for me, or at least lead me through how
to program it.) The 100Kc/s requirement isn't just fanciful
over-specification; this thing works on the signals that are well
outside the audio band and the 'scope needs to display them clearly,
despite all the audio clutter. The H.F. signals are higher amplitude
than the audio but are in the nature of pulses and occur infrequently.
(The analogue scope has to be Z modulated from rate-of-change to
emphasise the pulses and avoid screen burn, but this wouldn't be a
problem with an LCD display.)

https://www.ebay.co.uk/itm/275987222657
10MHz b/w (optimistic but probably better than 2Mhz) X-Y option.

That looks like the sort of thing, as long as it can be relied upon to
come up in X-Y mode without any user-input when power is applied. It
also needs to work in real time with no perceptible delay, so that the
user can compare the visual display with the audible sound.

Post by Martin Brown
I was assuming every engineer had a spare PC (or ten) lying around.

I haven't got any at all. I have a few Macs but my electronics career
was strongly influenced by an encounter with DOS, which I found so
utterly appaling that I abandoned digital computing altogether and went
back to working entirely in analogue.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Don Y

2024-08-29 18:23:39 UTC

I think that Daqarta software can probably do about what you want using the PC
stereo soundcard to digitise X & Y. 100kHz bandwidth might be pushing it but it
should be fine for audio up to 20kHz.

or any other sound card scope software,

I think the OP wants a "real-time" X-Y display. If it is acceptable to
treat this as a two-step process -- acquire data, display -- then
it becomes a lot easier to implement.

Post by Don Y
Does it *simultaneously* sample each channel? Or, toggle between them?

It makes an audio recording using commodity PC sound hardware.
https://www.ti.com/product/PCM2900C has 2 ADC channels

But, is that true of ALL "sound cards". Or, does it just have to *appear* to
be able to record two channels at audio frequencies?

Post by Don Y
The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

It's starting to feel like raspberry pi + LCD display + usb sound card.

The OP seems to want to avoid writing any code. And, to be fair, capturing
two 100KHz signals and pushing them onto a display while ERASING any previous
display content is a bit of a job, especially if you want to truly mimic
a 'scope in X-Y mode (where the display's persistence allows some portion
of "old" traces to remain visible before fading away (with the LCD, the
software would have to perform that function)

(think about how you would decide *what* to erase, given that a particular
pixel may have been painted as part of N consecutive cycles -- even if it
is the "oldest" pixel in a time-sorted list)

Jasen Betts

2024-08-30 06:36:07 UTC

I think that Daqarta software can probably do about what you want using the PC
stereo soundcard to digitise X & Y. 100kHz bandwidth might be pushing it but it
should be fine for audio up to 20kHz.

or any other sound card scope software,

I think the OP wants a "real-time" X-Y display. If it is acceptable to
treat this as a two-step process -- acquire data, display -- then
it becomes a lot easier to implement.

I think few millisecods latency will go unnoticed,

Post by Don Y
Does it *simultaneously* sample each channel? Or, toggle between them?

It makes an audio recording using commodity PC sound hardware.
https://www.ti.com/product/PCM2900C has 2 ADC channels

But, is that true of ALL "sound cards".

That is not important, avoid unsuitable devices.

Post by Don Y
The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

It's starting to feel like raspberry pi + LCD display + usb sound card.

The OP seems to want to avoid writing any code. And, to be fair, capturing
two 100KHz signals and pushing them onto a display while ERASING any previous
display content is a bit of a job, especially if you want to truly mimic
a 'scope in X-Y mode (where the display's persistence allows some portion
of "old" traces to remain visible before fading away (with the LCD, the
software would have to perform that function)
(think about how you would decide *what* to erase, given that a particular
pixel may have been painted as part of N consecutive cycles -- even if it
is the "oldest" pixel in a time-sorted list)

store a ring buffer of pixel coordinates and a raster size buffer of
pixel birthdays and then the update process becomes O(1)

look up the age(th) pixel in the buffer, if the age in the birthday map
is wrong then it has since been overwrittenm, so do nothing, else dim it a little.

this won't get you anti-aliasing, which is possibly more valuable,

Maybe there's a way to get both subpixel resolution and a fading effect.
perhaps some sort of palette rotation? does it actually need a
microcontroller? perhaps do the whole thing in an FPGA.

--
Jasen.
🇺🇦 Слава Україні

Jan Panteltje

2024-08-30 07:14:19 UTC

On a sunny day (Fri, 30 Aug 2024 06:36:07 -0000 (UTC)) it happened Jasen Betts

I think that Daqarta software can probably do about what you want using the PC
stereo soundcard to digitise X & Y. 100kHz bandwidth might be pushing it but it
should be fine for audio up to 20kHz.

or any other sound card scope software,

I think the OP wants a "real-time" X-Y display. If it is acceptable to
treat this as a two-step process -- acquire data, display -- then
it becomes a lot easier to implement.

I think few millisecods latency will go unnoticed,

Post by Don Y
Does it *simultaneously* sample each channel? Or, toggle between them?

It makes an audio recording using commodity PC sound hardware.
https://www.ti.com/product/PCM2900C has 2 ADC channels

But, is that true of ALL "sound cards".

That is not important, avoid unsuitable devices.

Post by Don Y
The advantage would be that you could locate the data acquisition
hardware separately from the (COTS) display.

It's starting to feel like raspberry pi + LCD display + usb sound card.

The OP seems to want to avoid writing any code. And, to be fair, capturing
two 100KHz signals and pushing them onto a display while ERASING any previous
display content is a bit of a job, especially if you want to truly mimic
a 'scope in X-Y mode (where the display's persistence allows some portion
of "old" traces to remain visible before fading away (with the LCD, the
software would have to perform that function)
(think about how you would decide *what* to erase, given that a particular
pixel may have been painted as part of N consecutive cycles -- even if it
is the "oldest" pixel in a time-sorted list)

store a ring buffer of pixel coordinates and a raster size buffer of
pixel birthdays and then the update process becomes O(1)
look up the age(th) pixel in the buffer, if the age in the birthday map
is wrong then it has since been overwrittenm, so do nothing, else dim it a little.
this won't get you anti-aliasing, which is possibly more valuable,
Maybe there's a way to get both subpixel resolution and a fading effect.
perhaps some sort of palette rotation? does it actually need a
microcontroller? perhaps do the whole thing in an FPGA.

OP wants to see needle movement
High speed camera and play back at any speed.
Smartphone?
I think mine has a high speed mode, but a bit more speed you should be able to get for a few dollars?

Don Y

2024-08-30 07:32:32 UTC

I think that Daqarta software can probably do about what you want using the PC
stereo soundcard to digitise X & Y. 100kHz bandwidth might be pushing it but it
should be fine for audio up to 20kHz.

or any other sound card scope software,

I think the OP wants a "real-time" X-Y display. If it is acceptable to
treat this as a two-step process -- acquire data, display -- then
it becomes a lot easier to implement.

I think few millisecods latency will go unnoticed,

So, you think you can chop the signal at 500Hz and the results won't
matter?

Post by Don Y
Does it *simultaneously* sample each channel? Or, toggle between them?

It makes an audio recording using commodity PC sound hardware.
https://www.ti.com/product/PCM2900C has 2 ADC channels

But, is that true of ALL "sound cards".

That is not important, avoid unsuitable devices.

The interface to the sound system dictates how the software *can* use
it. If there is never an expectation that the sampling can occur in lock
step, then the interface won't have provisions for that.

Or, do you expect a specific driver for a specific piece of hardawre
(presumably, the software that Martin mentioned, upthread, doesn't make
those assumptions)