Cheap oscilloscope-like displays?


From: John F. Woods (
Date: Tue May 24 1994 - 13:40:39 EDT

I want to build a "Poor Man's Spectrum Analyzer",[1] and I would like
to find some reasonably small and cheap way to display its output.
Usually, one uses a low-bandwidth oscilloscope in X-Y mode, but I'd
like to make this thing self-contained, if I can.** The most obvious
idea would be a handheld digital oscilloscope, but that fails the
"cheap" requirement in a really big way. Next would be to build my
own "digital oscilloscope" using a $69 dot-addressed display being
advertised in the current All-Electronics flyer, but that requires
doing a microprocessor board with A/D interfaces, and while I
certainly *could*, I anticipate it being a royal pain (to say nothing
of the gradually mounting cost that would entail); it also has the
disadvantages of placing a strong signal source next to a highly
sensitive spectrum analyzer, and also of having poor resolution. The
last possibility that occurs to me is to find an ancient oscilloscope
tube with maybe a 3" face, and building a low-bandwidth oscilloscope
around it (hey, I've got an old Handbook, it should be relatively easy).

So, does anyone have any experience with either of these alternatives
that they could share? Thanks.

73, John, WB7EEL/1

[1] In fact, I've been planning this for about 4 years, ever since I got
the parts for it...

[3] EDN magazine has a historical retrospective column, and recently
printed a review they did 50 years ago of some piece of test
equipment, which included the line "There's nothing like a substantial
oak case to give a feeling of quality to a test instrument." Because
of that, I intend to build my spectrum analyzer in a small oak case
(well, oak-faced plywood), and want to have the display inside the
case as well.

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