
FTLAB FSG-001 – A $30 Geiger Counter for Android and iOS - zxv
http://www.cnx-software.com/2016/07/29/ftlab-fsg-001-is-a-30-geiger-counter-radiation-detector-for-android-or-ios-smartphones/
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sandworm101
This thing can never be "accurate". Proper instantaneous measurements for
radiation require more than a good detector. The operator is part of the
equation.

Say you have two pieces of fish in front of you. Answering the question "which
one is more radioactive" requires more than holding a device over each for a
couple minutes. You have to think of the flux, the surface area of the fish
visible to the detector, the orientation of the detector, any background
sources, the mass of each piece and most importantly the distance between the
fish and the detector. That cannot be built into a hand-held consumer product.
Absent that, these devices will only scare people.

Note the pic in the OP showing the detector plugged in via an extension cable.
I'd bet that they moved it around until magically it's measurement lined up
with the other device.

Also, low levels of radiation are nothing to be concerned with. The linear no-
threshold model (the direct relationship between radiation and cancer) is no
longer considered appropriate when discussing very low levels.

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jkot
I assume it is just marketing. This is cheap chinese device. And spec says:

> _Measurement error – <30% within a given deviation between_

For many people even 50% error is acceptable. It is just to check if house or
hotel is safe. I live at place where radon, radioactive ashes, low
concentrations of uran.. are credible danger.

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sandworm101
30% is the error rate for measuring radiation AT the detector. In doing
something like comparing pieces of fish, with all the factors mentioned above,
I'd expect monumentally greater error rates, of several thousand
percentages... rendering the device useless.

There is plenty of evidence that the stress created by a device like this, by
an obsession with infinitesimal amounts of background radiation, does far more
harm. I see no net health benefit from such products.

Fyi, a 25% error rate detector can be build using a soup can and some string.
(Not a joke. This thing actually works.)

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

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Animats
Checking food with a gamma radiation detector is not too useful. [1][2] Some
"preppers" are into this, and get excited if they count for an hour and get
20% higher than usual. They're probably seeing ordinary variation in
background radiation, which varies over the course of a day.

A tester called LANFOS has been developed in Japan, to deal with possibly-
contaminated food from Fukishima. It's a round pot-like device with shielding
and plastic scintillation detectors into which a sample can be inserted. This
has been tested against other methods and the results agree with standard
laboratory tests.[3] That's a practical solution in an area where you really
do have to test.

If you're worried about suddenly encountering a big gamma emitter or X-ray
beam, get one of these.[4]

[1] [http://www.bloomberg.com/news/articles/2011-04-12/geiger-
cou...](http://www.bloomberg.com/news/articles/2011-04-12/geiger-counters-to-
find-radiation-in-meals-may-be-meaningless-) [2]
[https://www.princeton.edu/~ota/disk3/1979/7907/790720.PDF](https://www.princeton.edu/~ota/disk3/1979/7907/790720.PDF)
[3] [http://www.foodqualitynews.com/R-D/Radioactive-compounds-
det...](http://www.foodqualitynews.com/R-D/Radioactive-compounds-detected-
through-LANFOS) [4] [https://www.amazon.com/NukAlertTM-radiation-detector-
keychai...](https://www.amazon.com/NukAlertTM-radiation-detector-keychain-
attachable/dp/B004SZ2HXQ)

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hga
Note also the Banana Equivalent Dose
[https://en.wikipedia.org/wiki/Banana_equivalent_dose](https://en.wikipedia.org/wiki/Banana_equivalent_dose)
and the related observation by Edward Teller that due to the potassium-40 in
people, sleeping with two others gave roughly the same dose rate as being on
site at Three Mile Island (latter from memory)....

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delinka
I'm now interested in hearing about typical sleeping arrangements in Mr
Teller's day.

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bewaretheirs
Crowded apartments and poverty in early 20th-century Budapest?

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tomcam
That's what Mr. Teller wanted you to believe

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hga
Heh, sorry about the late reply, but his experience in the short lived
Hungarian Soviet Republic involved their "quartering troops" in
homes/apartments like his, something that at his age and the context he found
profoundly disturbing (this is from memory of the recently read and superb
_The Making of the Atomic Bomb_ by Richard Rhodes).

On the other hand, this was made as a semi-joke by him, so I'm sure it has
nothing to do with his memories of events back in 1919.

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techdragon
I'm actually reverse engineering this and similar cheap sensors as part of
creating an iOS app... I'm significantly motivated by how utterly _pathetic_
their companion apps are.

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MatthewWilkes
I'm using a GQ GMC320 this week and it's app is surprisingly bad. It even uses
the 16bit window sytle, which I didn't think possible.

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kwikiel
There is a need to verify how good this device is. What is measurment error

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wycx
Any guesses on what the sensor is in this device?

The marketing material says semiconductor sensor, which is a little vague.

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r3boots
Possibly one or more PIN diodes, cheap and cheerful if not particularly
sensitive:

[https://www.maximintegrated.com/en/app-
notes/index.mvp/id/22...](https://www.maximintegrated.com/en/app-
notes/index.mvp/id/2236)

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gravypod
I'd love to use this as an rng.

~~~
hatsunearu
If you're looking for some fun, you can reverse bias a zener diode and measure
the noise that comes out of it. It's shot noise, and you can measure it quite
easily with just some simple passives and an ADC.

~~~
gravypod
Wow never thought of that, that's a good idea.

I'll give it a try.

