Re: Job Offer

On Fri, 21 Mar 2025 18:21:35 GMT, cyclintom <cyclintom@yahoo.com>
wrote:

Tell everyone here what the conduction is in a swimming pool leak you damned fool? The problem isn't that you don't need 24 bit doesn't mean you can even START to get by with 10 bits. What sort of idiot believes that fresh water is a strong conductor?

No such thing as "fresh water".  Here are some common choices.  Which
one were you trying to measure:

          conductivity in micro Siemens per cm
Distilled water           0.5 -     3.0
Melted Snow                 2 -    42
Tap Water                  50 -   800
US Potable water           30 - 1,500
Freshwater streams        100 - 2,000
Industrial wastewater  10,000
Seawater               50,000
<https://atlas-scientific.com/blog/conductivity-of-distilled-water/>

For a time, I was the self appointed tester of water quality for a
small water district.  It was nothing fancy.  I was just trying to
determine if and when the local water district dumped something
disgusting into the redwood water tanks and ruined my coffee or tea.

For the purpose, I used an older version of a pH and TDS (total
dissolved solids) tester:
<https://www.google.com/search?q=tds%20tester&udm=2>
<https://www.ebay.com/sch/i.html?_nkw=tds%20meter>
Dirty or contaminated water has a higher conductivity.  I could easily
tell when the water district dumped too much hydrochloric acid into
the water tanks.  For drinking water, the EPA wants the TDS to below
500 ppm.  Easy (and lazy) conversion between TDS and ppm.
<https://pureaqua.com/tds-converter-calculator/>
<https://pureaqua.com/tds-ec-conversion/>

Why do you have to continually have to prove that you're not a design engineer. That 24 bit A-D was designed into that product by by Charley Button who has several international design awards and you're stupid enough to tell us that you know more than he. All I did was program it to work.

What Tom is trying to measure is the conductivity to 24 bit resolution
(16,777,215 bits).  Assuming the best case conductivity meter, with a
range of +15V to -15V DC, and with a 24 bit A/D, the 1 bit resolution
would be:
   30 V / 16,777,215 = 1.79 microvolts per bit.
Besides taking forever to obtain a stable measurement, the meter would
require platinum probes, an elaborate bridge circuit and very low
noise differential input amplifier to obtain an accurate reading.  I'm
not sure how to calculate the noise floor for such a precision device,
but my guess(tm) is that it will be very close to the thermal noise
floor.  In other words, that means that the thermal noise will like
dominate the measurement causing the indicated voltage to bounce
around.  Anyway, the design is overkill for a "leak detector".

The TDS testers previously mentioned have 4 decimal digits of display.
That would be 0 to 9999 ppm.  Converted to binary, that would be
10011100001111 or 14 bits (which is much less than 24 bits).  With +/-
1 digit (not 1 bit) uncertainty, 13 bits will suffice.  If an
averaging feature is added to stabilize the measurement, then 10 or 11
bits will suffice. 

All I did was program it to work.

Yep.  Here's some sample code for a TDS meter using an Arduino UNO:
<https://docs.cirkitdesigner.com/component/bcc7adac-432b-4e03-b535-1c22aacb9f68/tds-sensor>
<https://www.electronicwings.com/arduino/adc-in-arduino>
The UNO has 10 bits of resolution over a 0 to 5V range.
Since the Arduino UNO was first introduced in 2010, I would not expect
the hardware and your code to have been that simple.

Oddly, I can't find any mention of this project on your online resume:
<https://www.linkedin.com/in/tom-kunich-22012/details/experience/>



--
Jeff Liebermann                 jeffl@cruzio.com
PO Box 272      http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann      AE6KS    831-336-2558