• Low spec 'scope.

    From Liz Tuddenham@21:1/5 to All on Wed Aug 28 08:39:25 2024
    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.

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

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  • From Pimpom@21:1/5 to Liz Tuddenham on Wed Aug 28 14:27:56 2024
    On 28-08-2024 01:09 pm, 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: 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.

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  • From Liz Tuddenham@21:1/5 to Pimpom on Wed Aug 28 10:26:12 2024
    Pimpom <Pimpom@invalid.invalid> wrote:

    On 28-08-2024 01:09 pm, 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: 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.

    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

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  • From Jan Panteltje@21:1/5 to Liz Tuddenham on Wed Aug 28 10:29:06 2024
    On a sunny day (Wed, 28 Aug 2024 08:39:25 +0100) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1qyzrl3.ocj6lm4e4yaN%liz@poppyrecords.invalid.invalid>:

    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.

    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 :-)

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  • From Liz Tuddenham@21:1/5 to Jan Panteltje on Wed Aug 28 13:41:10 2024
    Jan Panteltje <alien@comet.invalid> wrote:

    On a sunny day (Wed, 28 Aug 2024 08:39:25 +0100) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1qyzrl3.ocj6lm4e4yaN%liz@poppyrecords.invalid.invalid>:

    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.


    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.


    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.


    Cost? Maybe the LCD is the most expensive part, 5 dollars?

    Very reasonable


    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.


    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

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  • From Martin Brown@21:1/5 to Liz Tuddenham on Wed Aug 28 15:47:59 2024
    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: 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 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

    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

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  • From Jan Panteltje@21:1/5 to Liz Tuddenham on Wed Aug 28 15:12:02 2024
    On a sunny day (Wed, 28 Aug 2024 13:41:10 +0100) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1qz05im.msb64xeltdhmN%liz@poppyrecords.invalid.invalid>:

    Jan Panteltje <alien@comet.invalid> wrote:

    On a sunny day (Wed, 28 Aug 2024 08:39:25 +0100) it happened
    liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in
    <1qyzrl3.ocj6lm4e4yaN%liz@poppyrecords.invalid.invalid>:

    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.


    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.


    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.


    Cost? Maybe the LCD is the most expensive part, 5 dollars?

    Very reasonable


    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.


    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!

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  • From Don Y@21:1/5 to Martin Brown on Wed Aug 28 08:32:46 2024
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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.

    --- SoupGate-Win32 v1.05
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  • From Martin Brown@21:1/5 to Don Y on Wed Aug 28 17:05:47 2024
    On 28/08/2024 16:32, Don Y wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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

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  • From Don Y@21:1/5 to Martin Brown on Wed Aug 28 13:05:44 2024
    On 8/28/2024 9:05 AM, Martin Brown wrote:
    On 28/08/2024 16:32, Don Y wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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).

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jasen Betts@21:1/5 to Don Y on Thu Aug 29 08:57:27 2024
    On 2024-08-28, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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,

    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

    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

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  • From Liz Tuddenham@21:1/5 to Jasen Betts on Thu Aug 29 10:43:29 2024
    Jasen Betts <usenet@revmaps.no-ip.org> wrote:

    On 2024-08-28, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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,

    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

    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

    --- SoupGate-Win32 v1.05
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  • From Jan Panteltje@21:1/5 to Liz Tuddenham on Thu Aug 29 10:36:58 2024
    On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1qz1rr1.1p7aq3z13xmh1aN%liz@poppyrecords.invalid.invalid>:

    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.


    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.

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  • From Liz Tuddenham@21:1/5 to Martin Brown on Thu Aug 29 13:10:42 2024
    Martin Brown <'''newspam'''@nonad.co.uk> wrote:

    On 29/08/2024 10:43, Liz Tuddenham wrote:
    Jasen Betts <usenet@revmaps.no-ip.org> wrote:

    On 2024-08-28, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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,

    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

    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.

    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.


    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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Jan Panteltje on Thu Aug 29 12:58:10 2024
    Jan Panteltje <alien@comet.invalid> wrote:

    On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1qz1rr1.1p7aq3z13xmh1aN%liz@poppyrecords.invalid.invalid>:

    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.


    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?

    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.


    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.

    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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Martin Brown@21:1/5 to Liz Tuddenham on Thu Aug 29 12:31:45 2024
    On 29/08/2024 10:43, Liz Tuddenham wrote:
    Jasen Betts <usenet@revmaps.no-ip.org> wrote:

    On 2024-08-28, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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,

    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

    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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Liz Tuddenham on Thu Aug 29 12:30:44 2024
    On a sunny day (Thu, 29 Aug 2024 12:58:10 +0100) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1qz1y4l.1m29ncv2qvc1sN%liz@poppyrecords.invalid.invalid>:

    Jan Panteltje <alien@comet.invalid> wrote:

    On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened
    liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in
    <1qz1rr1.1p7aq3z13xmh1aN%liz@poppyrecords.invalid.invalid>:

    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.


    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?

    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.


    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.

    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

    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.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Jan Panteltje on Thu Aug 29 15:39:00 2024
    Jan Panteltje <alien@comet.invalid> wrote:

    On a sunny day (Thu, 29 Aug 2024 12:58:10 +0100) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1qz1y4l.1m29ncv2qvc1sN%liz@poppyrecords.invalid.invalid>:

    Jan Panteltje <alien@comet.invalid> wrote:

    On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened
    liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in
    <1qz1rr1.1p7aq3z13xmh1aN%liz@poppyrecords.invalid.invalid>:

    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.


    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?

    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.


    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.

    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.


    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.


    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.

    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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Liz Tuddenham on Thu Aug 29 15:59:03 2024
    On a sunny day (Thu, 29 Aug 2024 15:39:00 +0100) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1qz24gk.1hnbmt81kso1e5N%liz@poppyrecords.invalid.invalid>:

    Jan Panteltje <alien@comet.invalid> wrote:

    On a sunny day (Thu, 29 Aug 2024 12:58:10 +0100) it happened
    liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in
    <1qz1y4l.1m29ncv2qvc1sN%liz@poppyrecords.invalid.invalid>:

    Jan Panteltje <alien@comet.invalid> wrote:

    On a sunny day (Thu, 29 Aug 2024 10:43:29 +0100) it happened
    liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in
    <1qz1rr1.1p7aq3z13xmh1aN%liz@poppyrecords.invalid.invalid>:

    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.


    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?

    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.


    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.

    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 :-)

    ~~~~~~ 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.
    https://panteltje.nl/pub/CD_box_binnenkant_IXIMG_0549.JPG

    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
    https://panteltje.nl/pub/xmpl.gif
    https://panteltje.nl/pub/xmpl_2020.gif
    https://panteltje.nl/pub/xmpl_2021.gif
    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
    https://panteltje.nl/pub/RF_FFT_plus_audio_FFT_plus_audio_AGC_plus_audio_compander_plus_audio_equalizer.gif
    latest xpsa spectrum analyzer also has FM stereo decoding...
    https://panteltje.nl/pub/xpsa-0.7.gif
    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.


    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.


    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.


    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.

    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.

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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Jasen Betts on Thu Aug 29 11:23:39 2024
    On 8/29/2024 1:57 AM, Jasen Betts wrote:
    On 2024-08-28, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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.

    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?

    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)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jasen Betts@21:1/5 to Don Y on Fri Aug 30 06:36:07 2024
    On 2024-08-29, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/29/2024 1:57 AM, Jasen Betts wrote:
    On 2024-08-28, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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,

    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 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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to usenet@revmaps.no-ip.org on Fri Aug 30 07:14:19 2024
    On a sunny day (Fri, 30 Aug 2024 06:36:07 -0000 (UTC)) it happened Jasen Betts <usenet@revmaps.no-ip.org> wrote in <varp8n$1bcop$1@gonzo.revmaps.no-ip.org>:

    On 2024-08-29, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/29/2024 1:57 AM, Jasen Betts wrote:
    On 2024-08-28, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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,

    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 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?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Jasen Betts on Fri Aug 30 00:32:32 2024
    On 8/29/2024 11:36 PM, Jasen Betts wrote:
    On 2024-08-29, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/29/2024 1:57 AM, Jasen Betts wrote:
    On 2024-08-28, Don Y <blockedofcourse@foo.invalid> wrote:
    On 8/28/2024 7:47 AM, Martin Brown wrote:
    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:  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 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?

    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)

    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)

    The intensity of a particular pixel would have to reflect its age-related contribution. E.g., if pixel (X,Y) has been "hit" on the last two cycles,
    it should be brighter than if it had been hit on the 500th and 501st cycles previous. Removing the 501st (oldest) should have less impact on the
    overall brightness.

    The overall brightness going forward has to reflect the sum of the aged
    "hits" over the past N cycles.

    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.

    Presumably, you want to refresh the displayed *data* at something close to
    the signal frequency (else there is the risk of missing artifacts).
    So, you need to store the mapped locations of each of the previous N
    10us samples and dynamically weight their ages into the intensity of
    the pixel that will *actually* be displayed in that location.

    Well suited to a parallel hardware solution -- save for the number of
    samples you want to keep in the queue.

    The OP likely has a better understanding of the number of samples required
    for the artifacts of interest to manifest, given that there are audio (?) frequency signals being encoded -- does the "problem" manfest more noticeably at higher signal frequencies? Or, when the channel difference is greatest? Or...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)