Geiger counter, detektor of beta and gamma radiation.

[gres]

I found tube from Geiger BOB33. To avoid thought it to the garbage, I decided to build tool for it.
Very useful was internet and some projects from the web. I didn’t make diagram so don’t look for it.
Principle of work is simple – into tube outputs, that is full of different gases, I put 340V of DC that comes from converter built on NE555 system, IRF840 transistor and 230/6V transformer.
When beta or gamma particle passing thought the tube, gas inside is ionized, and small discharge appeared. By part of second, through tube goes current. Then impulse is made and goes by transistor to monostable generator. Buzzer and microcontroller that counts impulses is connected to it.
Microcontroller is AT89C2051, software I wrote in C. So far soft counting impulses and display them on LED, but I want to add function ( button near the swith) that allow to display power in right unit. Unfortunately I have no idea how to write soft for that.
I also need :
Some information about this tube. There should be describe, how many impulse means which unit.
I know that voltage at tube is 350V but I can’t check that by measuring instrument, because current is so small, that resistance of instrument makes big errors. I don’t have any other idea how to check that.
About tube:
Type : BOB-33
Infill: Ne+Ar+Chloric extinguish unit
Voltage of shoulder : 300V
Voltage of work +40V
Plateau length : 80V
Plateau angle 0.125%V
Dead time 150 us
Longevity 10^10 impulses
Destination : measuring of beta and gamma radiation for portable tool.

Original text at: https://www.elektroda.pl/rtvforum/topic1575899.html

 

[karesz]

Hi,
Interesting,
but a silicon diode(must be in darkness!) with so at half cm2 surface makes some similar & dont need the HV bias, or is in all case smaller & robuster...
K.