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msgr
United Kingdom
3 Posts |
 Posted - 03/05/2025 : 14:37:54
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Hi,
I have a sensor pack (environmental, kinetic, etc) using an ESP32 device and I2C and I'm looking to add radiation detection. I saw the Pocket Geiger 5 which I can integrate using some PCF8574 counters. But I also now see the FTLab GDK101 which is direct I2C. My sensor pack is mobile on a vehicle. I do not want serial/SPI/GPIO etc, needs to be I2C. Any suggestions for suitable devices in a reasonable <EUR 200 price range? |
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| Reply #1
ullix
Germany
1189 Posts |
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| Reply #2
msgr
United Kingdom
3 Posts |
Posted - 03/06/2025 : 01:46:08
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Thanks, you documents are fantastic: great insights and food for thought.
I believed that I needed diode based rather than tube based due to the vibration/issues of a vehicle mount device, but I will rethink that due to the sensitivity benefits. The GDK-101 seems to have sampling limits that preclude it being used in a faster moving environment which is disappointing, so it seems ruled out. The Pocket Geiger 5 seemed not easily available.
I have chosen to stick with I2C as my PCB is already manufactured and designed for modular I2C plugin. Of course there are UART/I2C bridges (I'm using one for another sensor) if needed. But most rad detection seems like pulse counting and I already envisaged to do this for the Pocket Geiger 5 using 3x PCF8574 (8 bit I2C I/O device) fed by 2x 7HC4040 (12 bit ripple counter) which would give me 24 bit counter which I can easily read over I2C to calculate PPS.
I see your experimental results show the GMC series to be really good. Maybe I need one of these as a calibration source, e.g. a GMC300.
However, thanks your information and some more investigation, what I seem to have settled on is something like https://www.rhelectronics.store/high-voltage-geiger-probe-driver-power-supply-module-420v-550v-with-ttl-digitized-pulse-output or https://iot-devices.com.ua/en/product/ggreg20_v3-ionizing-radiation-detector-with-geiger-tube-sbm-20. I like the latter for the case, but it is designed for a longer tube (and can come with a J305). I think I prefer the LND712/Philips 18504. So likely I would choose the former and hack up (or 3d print) a case. I see I can buy LND712 or Philips 18504 tubes easily and here is a comparison: https://iot-devices.com.ua/en/comparison-of-geiger-muller-tubes-sbm20-j305-and-lnd712.
EDIT: I just ordered a GMC-500+ for experiment/calibration. |
Edited by - msgr on 03/06/2025 03:07:11 |
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| Reply #3
Michel2017
Germany
5 Posts |
Posted - 03/06/2025 : 22:06:09
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I have both, the Pocket Geiger 5 and the FTLab GDK101 in operation. The Pocket Geiger is just the sensor; the actual program code I have running on an Arduino. This works fine and you can program it as desired. However, as already mentioned by ullix, the sensitivity is very low. The background is about 5 counts per 20 minutes. But it gives accurate results compared with my various Geiger counters, but you have to wait ~30 minutes.
The FTLab has higher sensitivity and according to the data sheet comes „calibrated“ with sensitivity of about 12cpm/#956;Sv/h, which I found to be accurate. Compared to the Pocket Geiger, it is significant more sensitive (but of course, not comparable to a Geiger counter). However, the FTLab is a „full device“ and gives you on the I2C output only the #956;Sv/h every minute and averaged over 10 minutes. You can’t program it to get e.g., CPM etc.
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| Reply #4
ullix
Germany
1189 Posts |
Posted - 03/07/2025 : 00:22:36
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Re vibration I am sure you have noticed my comments that the PIN stuff is vibration sensitive, and FTLab "solves" this by switching off the counting when vibration is deteceted.
Re vibration in Geiger tubes I have never heard about it. I can't think about a possible mechanism, and don't think this concern is justified.
The sensitivity of Geiger tubes is roughly proportional to their volume and inner surface. Tubes from SBM20 to any of the cheap China glass tubes are sensitivity-wise in the same ballpark.
Pancake tubes, like in a GMC-600 counter, are about 2x more sensitive. But that's it!
You can really make a difference of 10x and even more sensitivity by moving to scintillator devices.The most prevalent are based on CsI(Tl) - Caesium-Iodide crystals doped with Thallium. When a gamma quant is absorbed in the crystal it triggers a light pulse. This pulse is detected by a photo sensor. The Radiacode devices https://www.radiacode.com/de are based on this technigue. Their sensitivity easily passes that of pancake detectors! Also, I can't think of a mechanism which makes them vibration sensitive.
You can raise a topic in this forum with a question on those crystals. I know of some people reading this forum, who are trying to build an open-source crystal device!
But not only is such a crystal device a more sensitive replacement for a regular Geiger counter, one can also generate gamma spectra with such a thing, allowing you to identify the radioactive source!
The light-flash intensity is increasing with gamma energy. Combine your electronics with a MCA (Multi-Channel-Analyzer) and you have spectrometer! The ESP32 built-in ADC might suffice for that.
GeigerLog can help you there as well. The most recent development versions - presently prerelease 1.6.0pre27 - (https://sourceforge.net/p/geigerlog/discussion/devel2/) will help you. As example here a Co-60 spectrum:
I will support any new achievement with GeigerLog.
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| Reply #5
Michel2017
Germany
5 Posts |
Posted - 03/08/2025 : 22:51:45
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quote:
Originally posted by ullix
Re vibration I am sure you have noticed my comments that the PIN stuff is vibration sensitive, and FTLab "solves" this by switching off the counting when vibration is deteceted.
The Pocket Geiger code does the same. The sensor board has a motion/vibration sensor as well. |
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| Reply #6
msgr
United Kingdom
3 Posts |
Posted - 04/01/2025 : 16:07:07
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Thanks! Probably still 3-6 months away from building/integrating this for real. For now, I received the GMC-500+ to play with and will do some testing. To help with that testing, I hooked it up to a spare rpi and wrote an mqtt interface to capture the data (https://github.com/matthewgream/gqgmctomqtt). When finished here the GMC will end up at our house in Sweden to live the rest of its life on my weather station (in an IP67 box) :-). |
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recommended device for embedded/i2c?
