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 Post subject: Radiation Sensor Board for Arduino
PostPosted: Thu Apr 14, 2011 10:08 am 

Joined: Mon Sep 28, 2009 12:06 pm
Posts: 11289
Radiation Sensor Board for Arduino

Quick Overview:
Detect Alpha, Beta and Gamma radiation integrating any Geiger Tube which works in the range 400V - 1000V and read this levels using Arduino. As well as from the terminal, the radiation levels can be shown using different actuators:

- Piezo: it allows us to hear the typical "chirp" common in the radioactivity counters
- Leds: 3 green and 2 red let easily to show low, medium and high levels
- LCD: it displays the counts per minute (cpm) and the equivalent absorbed energy levels in Servants (µSV/h).


Manifesto:
The main finality of the Radiation Sensor Board for Arduino is to help people in Japan to measure the levels of radiation in their everyday life. We want to give the chance to measure by themselves this levels instead of trusting in the general advises which are being broadcasted. The usage of this sensor board along with the affordable and easy to use Arduino platform helps people to get radiation values from specific places.

The design of the board is open hardware and the source code is released under GPL.

The Libelium Team. April 2011.


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 Post subject: Re: Radiation Sensor Board for Arduino
PostPosted: Thu Apr 14, 2011 3:37 pm 

Joined: Thu Apr 14, 2011 3:01 pm
Posts: 1
This looks like a good hobbyist project. You appear to be doing everything right.

Some things you may want to change:

Over here, native speakers who do not speak well are considered uneducated. When we read English which is not well written it appears to be from an uneducated writer.

We don't think this when something is written by a non-native speaker, but without knowing this most people will think that the article is written by an uneducated native speaker.

You might consider having a native English speaker go through it and reorder some of the words, or make a statement that you are not native English speakers. Either would be fine.

Consider changing some of the writing in your web page:

1) The measure of radiation dosage is "Sievert", not "Servant" as shown on your site. This fairly leaps out to a native speaker and should be corrected.
2) The diodes you use are "Zeners", not "Zenners".
3) There are some awkward English phrases in the description.

===========

From the circuit, it would appear that the high voltage output is regulated, but to only a single value. Each type of tube has a "plateau" value of voltage which is optimal for that tube and which is the correct voltage to use.

This article tells how to determine the correct voltage for each type of tube:

http://tech.groups.yahoo.com/group/Home ... essage/168

Your counter would be better if there were a way to select the correct voltage, and a table that lists the correct voltage for each tube.

===========

Geiger tubes have an aperture and a capture ratio. The aperture is the area of the tube which lets radiation in, and the capture ratio is a fixed number which is different for each type of tube.

Big tubes have large apertures and small "end window" tubes have tiny apertures. This means that the smaller end-window tubes are good for pointing at objects to tell if they are radioactive, but much less useful for monitoring the environment. The aperture is so small that it is statistically unlikely for a radioactive particle to pass through.

Big tubes have a larger aperture and are more sensitive, but not directional like the end window tubes. Big tubes are better for measuring overall radiation in the environment.

Consider posting a discussion about the types of tubes and what they are useful for. People will naturally want to purchase the best tube for their purpose, and there is no way to tell from your article.

Consider posting a discussion that talks about integration time and sqrt(n) variation in counts. If people will be using these to measure radiation in the environment, they will want to integrate the counts over a very long time (since the tubes are so small). Knowing what to expect would be helpful to a lot of people.


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 Post subject: Re: Radiation Sensor Board for Arduino
PostPosted: Thu Apr 14, 2011 5:23 pm 

Joined: Mon Sep 28, 2009 12:06 pm
Posts: 11289
thanks for the corrections. Although we are not native english speakers most of the mistakes are due to the rush to have everything ready as soon as possible. Regarding the new threads you comment we think is better to keep all this discussions here as we do not want the information to get dispersed.

Good idea to be able to regulate de final voltage using a potentiometer or something like that. We are open to add this new features in the coming up version. Please keep on sharing all the ideas to improve the design.


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 Post subject: Re: Radiation Sensor Board for Arduino
PostPosted: Thu Apr 14, 2011 7:44 pm 

Joined: Thu Apr 14, 2011 7:29 pm
Posts: 2
GREAT !

A couple of questions before I order mine:
-Due to the high tension, is it reasonable to use the shield without a box ? Would it be a good idea to offer it with a suitable box ?
-Is the LCD included ? (It seems clear that it is but if I'm not wrong, in some of the images or videos, there is no LCD).
-Is the shield assembled and ready to use ?

Some ideas:
-I'm more or less familiar with arduinos and can install the shield etc but I'm sure many people that will be interested in this product are not. Do you think it could be a good idea to sell it with the sketch uploaded, a box etc ?
-Include a memory card & a GPS to log the data.
-Integrate the radiation accumulated.


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 Post subject: Re: Radiation Sensor Board for Arduino
PostPosted: Fri Apr 15, 2011 6:34 pm 

Joined: Fri Apr 15, 2011 6:11 pm
Posts: 1
Hi,

we would like to donate a lot (up to 500 pcs) LCD 16x2
to Libelium to participate with the efforts done
with this Radiation Sensor for Japan.

it is a standard display should be compatible with your shield,
here is the datasheet: http://goo.gl/jykbs

Hope this is useuful,
Pls contact me.

Sergio Sorrenti
http://www.simplemachines.it
sergio.sorrenti at gmail.com


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 Post subject: Re: Radiation Sensor Board for Arduino
PostPosted: Sat Apr 16, 2011 2:49 pm 

Joined: Mon Sep 28, 2009 12:06 pm
Posts: 11289
Hello Sergio,
thank you very much for your donation!! We will contact you at the email provided.

regarding the post of Frikosal:
- yes, the LCD is included
- and don't worry for the 500V as the current which is generated is really low. Anyway, it will be always better to use it with a box in order to keep all the contacts isolated.
- the radiation acumulated can easily be calculated just adding each measurement to the previous one and saving this value in the EEPROM of Arduino.

regards.


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 Post subject: Re: Radiation Sensor Board for Arduino
PostPosted: Sat Apr 16, 2011 8:32 pm 

Joined: Thu Apr 14, 2011 7:29 pm
Posts: 2
A couple of questions more (already ordered one):
-Any idea about how to calibrate the radiation sensor or at least confirm the meaurements ? Is there a radiation source of known value ? Vaseline Glass output will (if I understood correctly) depend on the exposure to UV light.
-How would you implement more hardware (a gps and a memory card) ? It seems that other hardware should be below the radiation sensor.
-What about power ? Will it run with a battery during a reasonable amount of time ?


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 Post subject: Re: Radiation Sensor Board for Arduino
PostPosted: Mon Apr 18, 2011 5:15 pm 

Joined: Mon Apr 18, 2011 4:55 pm
Posts: 1
Hi!

Nice quick job on this :)

A couple of points though, based on a similar piece of gear that I've built:
1) You might be able to save a bit of money (and space on the board) by looking into transformers like this (http://www.bourns.com/data/global/pdfs/ ... series.pdf).
2) Based on what I saw looking at your schematic, you are not really concerned with the shape and spectral content of the resultant output pulse. You could increase the safety margin (to the arduino) by putting a fast optocoupler in that signal path. The 4-pin DIP ones from CEL are easy to use, and cheap to replace if they get nuked, but there are much faster ones out there.

We used (at my day job) the 10.5V primary version of that transformer for some geiger tube supplies, but they're a bit better than I expected and made it too easy to get way more voltage than I wanted. I'm going to play around with some of the 20V input ones that I've ordered in the meantime. They're super cheap and quite nice and small, IMHO, and I just used a pretty generic Royer oscillator design to drive them, using the provided feedback winding. Please feel free to drop me an email if you have any questions about any of this.

If you do go with such a transformer, you might consider implementing the second point, too. Small changes to how the high-voltage supply is done, combined with an optocoupler would easily give you enough galvanic isolation to protect downstream circuitry from all but the most outrageous transient events in the HV section. Just my $0.02 :)

Again - good on you guys for getting this together so quickly!


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 Post subject: Re: Radiation Sensor Board for Arduino
PostPosted: Mon Apr 18, 2011 7:43 pm 

Joined: Mon Sep 28, 2009 12:06 pm
Posts: 11289
#Answering Questions

@Fikosal:
- the Tokyo Hacklab is meeting with radiation experts who will help us to calibrate de the Geiger tubes. All the information will uploaded to the tutorial.
- regarding the energy consumption, give us some more time in order to make this test
- the idea of adding new modules such as the ZigBee, GPRS and GPS modules is being though using the Waspmote platform (we hope to have a brief article in a couple of days)

@Bacterium:
- thanks for your recommendations about the transformer and the other parts (that is the idea of opening the schematics!). We will take a look carefully and will contact you with any possible doubt.

regards.


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 Post subject: Re: Radiation Sensor Board for Arduino
PostPosted: Wed Apr 20, 2011 9:24 am 

Joined: Wed Apr 20, 2011 8:57 am
Posts: 1
very laudable step - however:

it is to be feared that proper calibration can not be guaranteed/is rather complex
publishing data which is not accountable/accurate is worse than not publishing anything.

what can be measured?
would help to list some possible use-cases, such as
can i measure radiation of my tap-water
can i measure produce in the supermarket
can i measure the soil of the playground


cheers,

andreas


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