MightyOhm.com

INST mode reports counts per minute based on taking the number of counts over the last second and multiplying by 60. Unlike the other modes, there is no averaging of counts over multiple seconds.

The source code is not compatible with Arduino. You'll need avr-gcc (WinAVR is no longer being actively developed but last time I checked I was still able to download and install it) and an AVR programmer like the USBTinyISP. Windows 10 may have some problems with drivers, since WinAVR is quite old ...

Bob,

Sorry I can't help you, I'm not familiar with rrdtool either.

Now I understand what you are trying to do. Geiger tubes aren't designed to work in this way, but you can try reducing the voltage to the tube - at some point the sensitivity will start to drop off. You can try adjusting VR1, but most likely you'll have to increase R8 as well. You could replace R8 w...

with batteries: 138g
without batteries: 116g

both include the case and tube. Removing the case will save about 60g.

Try a SI-3BG tube - it's much less sensitive than the SBM-20 and there are lots of them on eBay. Alternatively you can place some shielding around the SBM-20.

Are you trying to increase or decrease sensitivity?

I can think of a few ways to do this: Change Geiger counter tubes based on what you are trying to measure. Tubes with a larger cross section will be more sensitive. Tubes with a thinner wall or constructed with materials that pass more and lower energy radiation (like mica windows) will also be more...

I don't think this should be a problem. What is your power supply?

Antonio,

That is very cool, thanks for sharing an update on your progress!