Sorry no PIC here.

[JonW]

Seems to be alot of people on here monitoring radiation....   

[Wimax]

What is the current consumption of your Geiger Counter?

Hello Ken,

I confess I have to resurrect it, I parked it for several months waiting for parts from AliExpress so I could integrate it in an encloser ... devoting the time to other projects. Tomorrow I will try to check it out!

[Wimax]

Tip: If you place a voltage divider at the high voltage generator with 1 GOhm resistor and cheap pico-amp amplifier, you can set the Geiger tube voltage, monitor it without loading the generator and keep the high voltage constant. Here's one rock ... 

It's a smart solution, reading the voltage and changing the duty cycle ? I adopted a cascade of zener diodes to limit the HV, Data-sheet aside...I was a bit sceptical about how the zener actually works, but I had to change my mind.
Congratulations for the presentation of the data, that display is very nice!

[ken_k]

Tip: If you place a voltage divider at the high voltage generator with 1 GOhm resistor and cheap pico-amp amplifier, you can set the Geiger tube voltage, monitor it without loading the generator and keep the high voltage constant.

You design looks outstanding the GPS is a nice touch. I was unaware 1 GOhm resistors were available at such a reasonable price. Can you adjust the tube voltage via software?
This Geiger Counter design may turn into a competition! Maybe my next one should have double overhead chrome plated grease nipples.

[Fanie]

A Geiger tube will have an optimal voltage it will perform best from.
When exposed to bombardment will increase current flow, through a resistor can be detected and amplified.
A G-ohm resistor sounds like instability to me.

I cannot remember how the geiger tubes looked that we used, and I cannot remember that they ever went faulty despite the extreme conditions they worked in.  I would think the larger the tube, the more sensitive it can be for a specific radiation.  Certain tubes will be better for certain emissions, depends what it was designed for.

If you need 170V for a tube, it may not be so easy to generate that off a battery to get a calibrated output, but it can be compromised by using a small tube with less resolution that still give an acceptable indication for detection.
If you are to go on a site where there is contamination you would probably wear a tag that indicate when you had your dose of radiation (for the next 500 years  ) irrespective of what your instrument showed.  The more or less clicking is only an indication which direction the hornets nest is and if there is one.

Audible output is preferred to visual because it is difficult to watch the indicator when you move over difficult terrain.

[Fanie]

Btw, not all radiation is bad for us.  IR radiation is apparently good, while UV is considered bad, and fortunately UV-C is mostly shielded by the atmosphere.  Perhaps there is a form of nuclear radiation that is good for us, imagine you become a glow-in-the-dark without ill effects... or your eyes emit red beams enhancing your night vision.  Or just think you become invisible... I will be sooo naughty if that happens 

[trastikata]

A Geiger tube will have an optimal voltage it will perform best from.
When exposed to bombardment will increase current flow, through a resistor can be detected and amplified.
A G-ohm resistor sounds like instability to me.

This is why I regulate the voltage every few 10s of milliseconds. The high voltage monitoring is built around this circuit, the 1 GOhm resistor loads the high voltage circuit insignificantly and because it is behind the capacitor tank it is quite accurate.

Indeed the high tube count draws more current and the current circuit lags or overshoot with 3-5 volts when there's a high count change.

[Fanie]

I would use a power supply for the tube and a simple amplifier measuring a voltage over a resistor on the neg of the tube.  If the tube supply voltage does change with emission (ie conducting more), it will not matter because it would be in relationship with the amp output you get and can be compensated for very easy.
If you breathe on that G-ohm resistor it will change value...
I would use lower value resistors and rather amplify the smaller voltage output. 

[Fanie]

Something like this


The current flow through RVt will generate the input voltage to the opp amp.  The value should be so that the voltage is within the opp amp range.
If you're going to use a pic then the damping components to the right of the perforated line can be omitted as it is very easy to average the output of the amp, and / or read peak value(s) with the software.
For audio you can generate the clicking going faster as the emission increase, or play a low to high tone,
and beyond a certain value you play Les's Death March