Detector for rock hunting

[RobertD]

Here is a little tool I built recently, based on Matthias' Mini SiPM Driver Board, using a 1" dia x 1" CsI(Tl) coupled to a single MICROFC-60035 SiPM:
viewtopic.php?f=15&t=1089

When looking for radioactive rocks in the wild, I always found it annoying to keep my eyes on the display of whatever gamma detector I was using. Concentrating on small changes in click rate is also less than ideal.
On the other hand, the human brain / ear can easily and subconciously detect very small variations in tone pitch / frequency.
So I hooked up the Trigger/TTL output of the Mini SiD to an ESP 8266 programmed as a voltage controlled oscillator:

schematic.png (4.72 KiB) Viewed 15331 times

The arduino sketch for the ESP 8266 is also very simple, I'm sure there is lots of room for improvement:

Code: Select all

void setup() {
  pinMode(12, OUTPUT);
}

void loop() {

  int frequencyinput = analogRead(A0);
  frequencyinput = map(frequencyinput, 55, 1023, 100, 5000);
  tone(12, frequencyinput);
  delay(10);
}

The output (pin12) of the ESP 8266 connects to a passive piezo buzzer. A small LiPo battery powers the unit and can be recharged via USB.
The unit generates an audible tone with a frequency that increases with the amount of detected radiation.

Everything is installed in a standard DN 50 plumbing tube with end caps, available at home improvement stores, and a 3D printed handle:

[RobertD]

Here is a short video with the detector in action:

VID_20230611_185616.mp4

(5.53 MiB) Downloaded 763 times

[Sesselmann]

Robert,

Thanks for posting....

Well done, nice tidy package and from your video posted, seems to do the job well!

And regarding your sketch, can complain about 4 lines of code 👍

Steven

[Conor Whyte]

Thank you for that little bit of code - it's extremely useful for those of us that have analog meters or TTL output.
The fast diode 1N4148 coupled with a ~22uF low value electrolytic capacitor and 68KOhm resistor does the trick. I have modified the circuit a little to adapt it to my Bicron Surveyor MS / M . I am using a 10uF 16V Electrolytic capacitor and a ~40Kohm resistor both across the capacitor to TTL input and and another on the ground which connects to a mono-plug. This prevents the circuit from causing a ground fault in the meter which can damage the pulse processing ICs. When the meter is set to 1000x setting, any meter movement is turned directly into audio very quickly. I am also working on adding in a squelch to ignore background counts during the first 5 seconds when it is first connected. The particular sketch posted works fine on an arduino uno or pro without issue.