[FRIAM] the glow of tetrodes and pentodes

[Steve Smith]

Jon -

Thanks, great anecdote of your own.  

I have a "modern" scope in my shed that I'd give up in a heartbeat to
just about anyone I thought would put it to good use.   My son-in-law,
who is a musician began trading in classic sound gear maybe 6 years
ago.  He was excited for me to gift him the (circa 1985) oscilloscope,
but living in Beaverton OR at the time, it would have been like bringing
coals to Newcastle.   Before I could arrange delivery, he found one on
Craigslist locally... a Tektronix, if you can imagine that!  

In high-school, one of my 2 "best friends" had the benefit of having a
father who was an electrical engineer.   One of the things Ed's father
did with him was re-wire an old BW TV set to act as a very low-tech
O'Scope...   essentially exposing the horizontal and vertical deflection
circuitry with proper impedance matching for connecting up the output
from a stereo.   We would hang out in Ed's bedroom and listen to music
while it pulsed on the TV...   I can't remember the details but I think
he had some kind of frequency doubler/divider circuit that he could put
inline because I remember him being able to demonstrate more complex
(Lissajous) figures with other elements (tunable?) capacitors,
inductors, resistors that we could, along with the dynamic equalizer
"play with".    (I'm now guessing that he had a signal generator which
was where the lisajous and such came from).    

Unfortunately Ed's taste in music was pretty much limited to stuff like
Weird Al Yankovich and I can still remember the pulsing shapes from
Zappa's "don't you eat that yellow snow" where some sections dropped
into syncronized mono such that it was nothing more than a perfect
circle pulsing!

Need an Oscilloscope?

    (oh yeh, I think you can do this on a smart phone (or computer) with
a stereo input jack, or more DIY with a Raspberry Pi or Arduino)...

- Steve
> <3
>
> What a wonderfully rich and intimate portrait of a bygone era.
> The day I graduated from high school, my electronics teacher
> gave me a CRT-oscilloscope and a bag of vacuum tubes. For
> years I would enjoy watching records on the scope while listening
> on my Fischer 400 (the receiver I still rock today). It was amazing
> to dial into something periodic in the music, a choice of basis for
> visualizing the sound, enjoying the cleanliness of pure sine waves
> from digital bass or the thick-fuzziness of Penderecki's micro-tonal
> strings. All the while, the powerful pentodes blanketing the room
> in warm orange light.
>
>
>
> --
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