[NLRS] piezoresistive transducers

[Douglas H Reed]

Based on Jerry's research, my guess would be that some Marketing type
has confused "resolution" and "accuracy" when creating the advertising
for the device. Resolution is easy to achieve but accuracy is
something entirely different.

We all do it. Haven't you ever used a cheap DVM to measure a voltage
and written down a result with 4 digits? When the rated accuracy of
the DVM was spec'ed at maybe 2% full scale? My first exposure to this
was over 40 years ago when my Physics teacher told me that he didn't
want to see results to 7 decimal places from my shiny new calculator,
when the numbers involved only had 2 decimal places. Since then I've
never forgotten that 1.5 volts is not the same as 1.500 volts because
the implied accuracy of the reading is much different.

In practical terms, Jerry has shown that you can safely disregard what
the article says about accuracy since you probably don't have enough
money to ensure a level of calibration which would let the readings
mean something in the outside world. But that level of resolution
might be useful when making relative readings, assuming there is a
useful amount of correlation between the original reference and the
final target of the adjustment.

OTOH, if you decide to make a voltage reference standard to calibrate
your cheap DVM, there are a number of high-accuracy voltage reference
chips available as free samples from Analog Devices and Maxim IC's.
W1GHZ wrote an article about building one many years ago. And for
sensors, a lot of new chips are just black boxes with a simple serial
interface to a microprocessor and laser-trimmed factory calibration.
The whole series of Maxim One-Wire devices come to mind......

73, Doug Reed, N0NAS.