Re: Low spec 'scope.

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)