
Show HN: I built a desktop radiation monitor with Raspberry Pi, brass and wood - chrisys
https://www.balena.io/blog/show-tell-a-steampunk-desktop-background-radiation-monitor/
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SiempreViernes
I was wondering how you would detect radiation with brass and wood, but it
turns out this was actually talking about how to build a snazzy enclosure and
not at all about how to detect radiation : /

~~~
ISL
I assumed that someone had made a sensitive bolometer.

[https://en.wikipedia.org/wiki/Bolometer](https://en.wikipedia.org/wiki/Bolometer)

Wood is a thermal insulator, so with care, one might be able to build a
thermistor bridge capable of detecting the differential temperature rise
between pieces of brass when a source was placed near one brass-piece.

I, too, found that the expectations framed by the title were not met by the
article. It's a pretty box, though.

~~~
trhway
>By 1880, Langley's bolometer was refined enough to detect thermal radiation
from a cow a quarter of a mile away.

Sidenote: that sounds like even F-22/35 should be visible half a globe away in
IR

~~~
schoen
Be careful of that inverse square law—it's a doozy!

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staycoolboy
Looks fantastic! Well done!

Why didn't you go full brass on the decatrons, instead of mixing stainless and
copper? Same goes for the counter box: you only wrapped 2 sides when you
pro'lly could have wrapped the whole thing in brass... you probably saved
yourself 10 hours by not doing that, but you're already in for what, 30 hours
already?

Now I'm going to nitpick. :) My only critique is the high gloss finish on the
wood looks unfinished in the final assembly picture: you can see
drips/wrinkles, and the grain wasn't filled which isn't a good match with high
gloss, or if unfilled a hand-oiled finish would not have called attention.
This is a consequence of working with mahogany. (And what's with the hand
filed-gouges in the cutouts. Yes they are hidden, but details count, man!)

I'm also jealous you have a machine shop. Very jealous.

Super job!

~~~
chrisys
Thanks for the compliments, and I appreciate your eye for detail and
nitpicking :) I don't even wanna think about how many hours I put into this
thing. It was one of those projects when you've got some free time you just
keep working on it, then eventually, one day, it turns out there's nothing
else to do.

For the Dekatrons, it was simply a case of I had 50mm stainless steel bar
already in the shop, but the biggest brass I had was probably 30mm diameter. I
bought a whole load of bar stock offcuts from an auction years ago and pretty
much everything I make is made from that lot. That being said I broke so many
tools trying to work with M2 threads in stainless that I could have just
bought some brass bar!

As for the dips/wrinkles in the case, those were caused by my use of an
oscillating drum sander. There's a photo in the blog post where you'll see I
used the drum sander to bring the lid to size. I foolishly let it mark the
previously pristine planed surfaces, and didn't realise until I had coated it
with gloss. This is definitely a lesson learned from this project, I won't
make that mistake again.

I have no defence for the hand-filed gouges hidden in the openings, and not
filling the grain - more lessons learned for next time there. :)

Thanks for the comment!

~~~
jacquesm
Super job. More nitpicking: the real fanatics line up the screw heads to the
geometry of the piece. For instance the Dekatrons would look nicer if the
screwhead slots would form a circle too.

~~~
chrisys
You're totally right of course, I was very afraid of snapping those little
guys off :)

~~~
jacquesm
Quarter turn before breaking is the right torque ;) Again, super job. Be
prepared for a lot of brass polishing.

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wolfhumble
The wood, the brass, the tubes, the clicks, the faint light from the
indicators, the tech . . .

Absolutely beautiful, thanks for sharing!

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dec0dedab0de
the title reminds me of a Mitch Hedberg joke: """They say the recipe for
Sprite is lemon and lime. I tried to make it at home. There's more to it than
that."""

This is awesome though, I especially like the mechanical counter.

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overfl0w
Great work! I liked how well the vintage look and the modern core fit.

I'm not sure where I read it but it was stated that the Geiger counters which
are manufactured after the Chernobyl (?) incident were not as accurate as
those manufactured before it. The reason is that all the metal after the
incident and the radiation experiments performed afterwards is contaminated
with radiation particles which alter the radiation readings of the Geiger
counter. Correct me if I'm wrong about this one.

~~~
matthewmcg
I don’t know about Chernobyl specifically, but so-called low background steel
from before 1945 is harvested specifically for use in radiation sensing
applications. See [https://en.wikipedia.org/wiki/Low-
background_steel](https://en.wikipedia.org/wiki/Low-background_steel)

I think most of the radionuclide contamination comes from Cold War atmospheric
nuclear testing.

Some low background steel is recovered from sunken battleships!

~~~
arethuza
On a related note - the day the German fleet (which went on to be scuttled at
Scapa Flow and to become a source of that low-background steel) must have been
quite an incredible sight - possibly one of the largest collection of warships
ever (40 battleships, there were only 7 at the Normandy Landings):

[https://www.bbc.co.uk/news/magazine-30128199](https://www.bbc.co.uk/news/magazine-30128199)

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dekhn
I wanted to work with dekatrons (my initials are dek) but the actual dekatron
tubes want 300+V, which exceeds my personal comfort level. However there is a
nice kit with all the necessary electronics:
[https://threeneurons.wordpress.com/dekatron-
stuff/variable-d...](https://threeneurons.wordpress.com/dekatron-
stuff/variable-dekatron-spinner-kit/)

~~~
schoen
I wonder how many people ever get to work with equipment that has the same
name as they do!

[https://en.wikipedia.org/wiki/Nominative_determinism](https://en.wikipedia.org/wiki/Nominative_determinism)

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sneak
Great device, and great content marketing.

Remember well that Balena are the people who built spyware into a SD card
flashing tool: essentially a GUI for running dd.

[https://github.com/balena-io/etcher/issues/2497](https://github.com/balena-
io/etcher/issues/2497)

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dandigangi
3.6 roentgen. Not great. Not terrible.

Very cool project. Always impressed the level craftsmanship some people have.

~~~
acidburnNSA
If anyone wants some context about radiation dose units across various orders
of magnitude, I recommend the charts in this DOE chart (see page 6) [1]

[1] [https://www.energy.gov/sites/prod/files/2018/01/f46/doe-
ioni...](https://www.energy.gov/sites/prod/files/2018/01/f46/doe-ionizing-
radiation-dose-ranges-jan-2018.pdf)

~~~
dandigangi
Was expecting someone to downvote me because they haven't seen Chernobyl on
HBO. Haha

~~~
chrisys
The opening line of my blog post was almost a reference to this, then nobody I
had proof read the post got it so I took it out :P

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stepstop
Incredible! Thank you for writing this up & sharing this! I’ll need to come
back and read every word later but wanted to share my thanks. We need more
like this on HN and less of the politics

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snak
Looks amazing. Dekatron tubes are great, I didn't know what they were called,
thanks for sharing.

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dkarp
I remember seeing this role (maybe it was
[https://workaline.com/listing/38e26af8](https://workaline.com/listing/38e26af8))
listed at Balena last year.

What a fantastic job. Free hardware and freedom to build super interesting
projects as long as you can fit Balena in somehow. It's also a much better
alternative to facebook ads or similar for a company's marketing spend...

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ChrisMarshallNY
I like seeing some of these “ephemera” projects highlighted (like the kosher
search engine and the manila folder 777).

We can do some cool stuff.

Thanks for sharing this!

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hanoz
Lovely piece of work. Scary how active those old gas lamp mantles are (in the
video). Makes me wonder how radioactive your average campsite is, given that
those things tend to crumble to dust when you change them.

~~~
throwanem
Not very. The predominant isotope of thorium is an alpha emitter with a half-
life measured in tens of billions of years.

Looking at the video, the counter appears to peak around 200cpm, or (per the
Grafana dashboard screenshot) about 2 microsieverts per hour. That'd take 50
hours, a little over two days, of exposure to add up to the dose of a typical
chest X-ray. And that's for a whole mantle, placed directly adjacent to the
tube; it's not obvious in the video, but the dose rate is highly dependent on
distance. Spicy gamma emitters aside, most small samples drop to background
just an inch or two from the detector.

So I wouldn't worry all that much about it, really. Eating a mantle, or
breathing the dust from a freshly replaced one, wouldn't be a great idea; I'd
expect it to increase cancer risk to a degree probably commensurable with some
number of years of smoking. (Probably fewer years than I racked up, back when
I still had the habit.) Nor would keeping a mantle in your jockeys, or your
bra. So don't do any of those things.

But buried, or even just mixed with dirt? I'd worry more about falling into
the fire, and that's not something I worry about a lot, even if it does
typically get pretty drunk out every time I ever go camping with anyone.

~~~
walrus01
For comparison I have seen statistics that a granite countertop, or granite
flooring can emit around 1.7 microsieverts per hour. Granite is mildly
radioactive. I imagine working in an old 1920s era office building with
granite column facing materials and granite hallway flooring would be a lot
more radiation load on the body, unless you spent dedicated time every day
seeking out and handling gas lamp mantles.

Lots of people have marble and granite countertops in their kitchen...

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PeterBarrett
This is really beautiful craftsmanship! It will definitely influence my own
projects in the future, thanks for sharing.

~~~
chrisys
Thanks for the compliment Peter, if I can inspire others like yourself to get
building, I'm happy :)

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bb123
This is really fun. I love the idea that something so old looking is running
some state of the art stuff behind it.

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imrehg
Very well done, Chris, this look gorgeous, and super well detailed!

~~~
chrisys
Thanks Greg, nice to see you here :)

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costcopizza
Wow, beautiful work!

Where can I find more, similar projects to this one?

It doesn’t even need to have electronics in it, I just have the itch to try
and build something, but literally do not know where to start.

~~~
draugadrotten
for inspiration .... [http://www.lovehulten.com/](http://www.lovehulten.com/)

~~~
drewzero1
This is great! I especially love the PET De Lux. Saving this one for later.

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jlengrand
The sheer amount of work ! Well done and beautiful!

~~~
chrisys
Thanks - it was _so much_ work, but super rewarding as the thing looks
beautiful on my desk. It's awesome to see it's appreciated :)

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Animats
Steampunk was fun, but it's kind of over. I've done the brass and wood and
gears thing.[1]

(I miss the TechShop era. For most of the life of TechShop, I had a membership
there.)

[1] [https://vimeo.com/124065314](https://vimeo.com/124065314)

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Luc
I wish there was a cheap way to calibrate low-cost or surplus radiation
monitors.

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BolexNOLA
Wow man. Nothing to add, this is just gorgeous

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zeristor
It is known that the banana contains small amounts of radioactive postassium,
perhpas it would be possible to use a banana for scale?

[https://en.wikipedia.org/wiki/Banana_equivalent_dose](https://en.wikipedia.org/wiki/Banana_equivalent_dose)

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dvt
Obviously a marketing piece, but a _ton_ of work went into it, so I'm sure HN
will be kind ;) In any case, this is a very awesome build!

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anakaine
Marketing? It's a one off build.

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crispyporkbites
It’s marketing for the cloud iot platform on the blog

~~~
uptown
Also wood. He used wood and clearly is in deep with the hardwood movement.

