radiation meter November 2011

Equipment, circuits, projects, procedures

Postby thijsbeckers » Mon Mar 26, 2012 12:00 am

Hi alefbe,

We haven't seen this problem before. Could you please check that your RX connection from BOB to processor board is working properly?
thijsbeckers
 
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Postby alefbe » Tue Mar 27, 2012 12:00 am

Hi Jan,

I will send you details on how I connected the "probe" to Arduino.
I also plan to send you by e-mail a couple of pictures and screen captures. I am not at all an electronic expert (by the way I am a chemist!) but I have enough electronic knowledge to assemble a kit and understand the basics of how it works.
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Postby teemo » Sat Mar 31, 2012 12:00 am

Hi,
Is it possible to improve the meter to handheld version, so that test objects must not be inside the can with the meter?
I did built the radiation meter from the kit. It is very sensitive indeed and shielding is a challenge.
It should work if to drill small hole to the shielding and place sensor directly behind and then cover the hole with some material that lets the radiation pass but stop the light.

Anyone tested some filter materials already?

I propose we make some tests with: 1. thin black plastic that is used packing photographic film. 2. Mica painted with black paint.

Wiki says that some Geiger–Müller tubes are covered with mica and are still able to detect alfa radiation. So we sould at least be able to detect beta radiation through mica and paint.

But first I will get some radioactive samples to test with.
teemo
 
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Postby thijsbeckers » Mon Apr 02, 2012 12:00 am

Hi Teemo,

Some nice ideas you have there. I haven't tried with mica or heard of anyone experimenting with it, so I would like to hear your results.

Like you said, it should work if you drill a small hole and place the sensor directly behind it.

Keep us informed!
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Postby pierrot29 » Tue Apr 03, 2012 12:00 am

Hi everybody!

I am making this radiation meter too, in the source code, it display only the CPM number. I would like to know if someone know how to convert this value in Sievert/h. Thanks by advance.
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Postby alefbe » Wed Apr 04, 2012 12:00 am

Yes I have checked the connection RX to BOB and it looks ok. By the way I bought two BOBs and set them for 5 V and 3.3 V respectively.
I tried them both with the radiation meter but I still could not change the L level.
alefbe
 
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Postby thijsbeckers » Wed Apr 04, 2012 12:00 am

Hi Alfbe,

Very strange indeed! Hold on, I will check with the author. I'll get back to you.
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Postby thijsbeckers » Wed Apr 04, 2012 12:00 am

Hi alefbe,

Could you check (with an oscilloscope) whether data arrives at the PD0 pin (pin 2) of the µC when you press the 'Level' button? Only one byte is sent, so it will be very brief. If this is the case, I see no other option then to send you a new (checked) µC.
If you're not seeing any data coming through, you should check the signal route from the BOB to the PD0 pin.

Let me know if it works out.
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Postby micro_pepe » Wed Apr 04, 2012 12:00 am

thijsbeckers800 mVpp seems too much to me. My prototype only shows about 50 mVpp noise.
R5 and R7 should both be 10k. There were some last minute corrections in the schematic, that perhaps couldn't be entered anymore/magazine was already at the printer.
You should use a BF245B. As written in the article, the operating point is shifted when you use an A or C version.
I didn't notice the strange L154 indication yet, but I also didn't set the threshold to 100. I guess this will be ok when you have your hardware running properly.

Good luck and let us know if it works out!


Well, I have 10K resistors and BF245B, and the results are good, with a level of 60 gives an average of 0.15 counts / min.

Thanks for everything.
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Postby thijsbeckers » Fri Apr 06, 2012 12:00 am

micro_pepeWell, I have 10K resistors and BF245B, and the results are good, with a level of 60 gives an average of 0.15 counts / min.

Thanks for everything.


I'm glad it worked out. Sounds about right.

No problem.
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