[TriEmbed] Hacking a fake vintage radio (with Arduino + Pi 0)

Scott Hall scottghall1 at gmail.com
Mon Jun 29 20:13:27 CDT 2020


Hey great project Huan!

I am into restoring or refinishing old antique radios and cabinets, and
have implemented more than one "fake vintage" radio using a microcontroller
- in the recent half-decade using SDR radio.

Over the years I had to implement a true random number generator on a
microcontroller or small computer many times.  My go-to circuit ever since
my freshman year of college has used a germanium transistor plus an op-amp
filter to provide the random seed. I have also the math overrun digits of a
multiplication of two values sequenced from a small table of truly random
numbers, though this worked better in older chipsets.  More recently I have
used the value from a RTC or values read from a GPS chip or NTP value as
the seed value.  But the pink noise generated by a germanium transistor has
the fastest solution and is more evenly and flatter spread
statistically than any other solution I have measured.  And great for
generating the signal required to create the sound signal for a parametric
autotune of the filter path for a flat response to room acoustics, amp and
speaker response, and microphone pickup of a sound system.

- sgh


On Mon, Jun 29, 2020 at 8:47 PM Huan Truong via TriEmbed <
triembed at triembed.org> wrote:

> Thanks, I sent it to the HAD staff via their "submit a hack" link on
> their homepage and they are very kind. This is not the first time I've
> done that and I really like the HAD staff. I hope it will wake up the
> creativity of someone. In real life, this whole system looks actually
> pretty attractive (and sounds nice, as I usually connect an external
> amp to the faux radio whenever I don't feel nostalgic).
>
> https://youtu.be/QgBCnwq8A4g
>
>
>
> As a side note, getting random numbers out of a (deterministic)
> computer is really hard. Getting nice, uniform numbers out of any
> system is even harder, that's why cryptography is so hard. There is a
> friend of mine, a significant and proud part of his work at Google is
> to create a library that makes it easy to call cryptographic
> functions. Specifically, part of it is to make it hard for programmers
> to mess up/misuse the RNG.
>
> On Sun, Jun 28, 2020 at 7:41 AM Kevin McClaning via TriEmbed
> <triembed at triembed.org> wrote:
> >
> > Excellent write up, Huan.
> >
> > Speaking of "silly" and "No one cares about," I once bought a scrolling
> > LED sign at
> > a ham fest but couldn't find documentation. I reverse-engineered the
> > hardware so
> > I could directly access the LED matrix with an Arduino, then set it
> > about displaying
> > humorous/motivational messages (of the kind you see at the bottom of
> > slashdot),
> > along with some random numbers and graphics.
> >
> > No, it doesn't stop there. I used the Arduino random number generator to
> > select the individual
> > messages to display but, I noticed that it always produced the same
> > "random" order of messages.
> > This annoyed me, so I added a temperature sensor and used its output to
> > increase the entropy
> > of the Arduino. Since I was in the "increase the entropy" neighborhood,
> > I build two audio oscillators,
> > with crappy stability and ran them into the AD converters of the
> > Arduino. I sampled the waveforms
> > every now and then and fed that into the Arduino's random seed as well.
> >
> > Yeah, "silly" but it was a fun diversion. Did all this in the
> > before-the-pandemic timeframe.
> >
> > Kevin
> >
> > On 6/24/20 12:43 PM, Huan Truong via TriEmbed wrote:
> > > This has taken me way more time than I thought, but finishing this
> > > retrofit is a big achievement for me. It's really silly and serves
> > > exactly no purpose other than RE'ing something no one cares about.  So
> > > I just want to share for some shits and giggles.
> > >
> > >
> http://www.tnhh.net/posts/adventures-hacking-fake-vivitar-vintage-radio.html
> > >
> > >
> > >
> > >
> > >
> >
> >
> > _______________________________________________
> > Triangle, NC Embedded Computing mailing list
> >
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>
>
> --
>
> Huan Truong
> www tnhh.net / twitter @huant
>
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-- 
Scott G. Hall
Raleigh, NC, USA
scottghall1 at gmail.com
*Although kindness is rarely a job, no matter what you do it's always an
option.*
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