GeigerPhone (Geiger Counter circuit) using LMC555:
This circuit can be connected to a smartphone (Android, iPhone – using GeigerBot with Jack adapter cable) or PC sound card (MIC IN).
Can be powered using one or two AA rechargeable or alkaline batteries.
The HV for the tube can be set with the R3 trimmer.
Geiger Counter using microcontroller:
The project details and firmware can be downloaded from here: geigercounter_v1.zip
In this project I used a SBM20-1 GeigerMuller tube and an ATtiny2313 microcontroller.
This circuit can measure Gamma Dose Rate (GDR), Counts Per Minute (CPM) and Counts Per Second (CPS).
Also if you want you can connect to the PC for data logging, using this small free application available here: UGP
Then it is possible to import the values saved in a txt file (by UGP) to OpenOffice Calc and generate different charts: Chart Example
Use for educational purposes only!