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From: liz@poppyrecords.invalid.invalid (Liz Tuddenham)
Newsgroups: sci.electronics.design
Subject: Re: Low spec 'scope.
Date: Wed, 28 Aug 2024 13:41:10 +0100
Organization: Poppy Records
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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