MightyOhm.com

Hi,
First I want to thank you Jeff for this great schematic, even if I don't fully understand it
What is my problem? I want to connect Geiger counter (without ATtiny2313) with Arduino Due. I make my own pcb, checked schematic (only part with Geiger tube) if it is the same like yours, double checked it. Voltage on HV test point - 400v measured with Meratronik V640 (100M Ohm) so I think it is good.
Voltage on test point where pulse should be: 1,37v or 0,04v (when i short + and - of tube). Measured with simple digital multimeter, this 1,37v might be problematic because of CMOS logic level.
Voltages on pins of timer (measured with simple digital multimeter):
1. 0v
2. 1,68v
3. 1,15v
4. 3,11v
5. 2,16v
6. 0
7. 0,5
8. 3,26v

Now when I connected buzzer to pulse point, buzzer make noise all the time with short time of silence when (I think) tube detect gamma particle. So in theory it works, but if I touch with finger + or - of tube or even grund plane of pcb (with solder mask on it) buzzer goes crazy. Now I conected puls point with pin of Arduino DUE and attach interrupt (falling) and for first 5s it works great (if Arduino triger interrupt, make buzzer connected to it HIGH and after 100ms LOW), after that buzzer start to click faster and it end with countinous noise. Is possible to make readings from pulse point more cleaner? In above case Arduino (USB) and Geiger(3,3v) have two separate power supply.

Thank you for your time,
Arek

Hi Arek,

I can't provide much help as you didn't purchase a kit. You are probably experiencing noise from the HV PS coupling into the digital input of the Arduino. Make sure your PSU is separated from the Arduino (including all wiring). Without seeing a schematic it is hard for me to provide more help.

Jeff