MY new PIC uC ION Detector

[goldfinder]

Originally Posted by J_Player

Hi Goldfinder,

Your circuit is very interesting.
It represents the first understandable improvement over the simple static detectors I have seen in this forum.
I have seen other signal processing circuits intended to detect ionic activity by extracting signals from narrow time intervals.
These circuits involved more complicated discrete digital circuitry to filter and process short interval signals, but they were never published here.

I suspected you would not have detected any signs of ionisation from long time buried gold with your ion detector, as you confirmed.
I am wondering how you determined the ion burst time interval to program your PIC to.
From what you posted, I am guessing you may have calibrated it to an air ion generator which produces ozone, or possibly some other source of ions?

Second, I am wondering how you originally discovered that ions will create bursts of pulses within a given time interval.
Is this something you discovered on your own, or is there a printed source you learned this from?

Best wishes,
J_P

JP,
Very good questions! I answer both as a combination.

I made the simple electrostatic detector using a jfet which is in many places on the internet. I also made the zahori circuit. I noticed with both that there was some kind of pulse so I hooked up the circuit to my oscope and could see the pulses. Walking on the carpet, running a high voltage spark generator, combing my hair (when I still had it longer), rubbing a glass rod on a cloth, etc., and for the most part the oscope pulses were within a fairly narrow range. Higher voltages seemed to be longer probably because there was more energy to dissipate so as I remember I discounted these as not as likely in nature. It seemed logical to me that when an ion decayed or combined with an opposite charge it would release a pulse of electromagnetic energy. And the oscope seemed to confirm.

Then I designed a PIC program that would interface with the zahori circuit. When the PIC got an electrostatic indication from the ES circuitry, it timed the length of the pulse (PICs have some good timers) and if the pulse was within the timing window the PIC output a pulse. Basically, the PIC needs to keep reading the A2D port of the PIC and test for voltage ups to detect the pulse start and test for voltage downs to get the end of the pulse and measure time the between pulse up and pulse down.

Timing is only as accurate as the PIC clock cycle time. Faster PIC clock like a crystal oscillator at 20 Mhz vs the internal PIC clock at 4 Mhz gets you to more accuracy. However, crystal oscillators also cost the circuit in battery power. I chose the 4 Mhz internal as it was accurate enough for the ion pulse width window.

You can also create your own timing by counting the clock cycles taken by the PIC to do something.

I did field tests and found some interesting things. One very interesting effect was that walking on rocks or sand created ionic activity that the detector would detect quite readily. So if you are walking and try to detect ions you are always going to detect ions. Another was that lots of trees and shrubs had big charges and rubbing against them cause ionic sparking.

Interesting learning experience as a minimum!
Goldfinder