MET100
High accuracy RTD temperature calibrator, you can see this item is in the RS
catalogue 423-6578. I designed this RTD instrument for Metartec as the
MET100 there was nothing on the market to touch it, it was sold off to time 
electronics and renamed 7000 PT100, this was one of the first instruments to
use an delta-sigma ADC and DAC to give 21 bits of accuracy, the instrument
was controlled by a 2K PIC by Microchip, I wrote all the third polynomial
and control algorithms at low level and fitted it all into a 2K chip. The entire range of the instrument is dependent on only one 2.6K 3PPM
resistor using a delta-sigma ADC in differential mode; the instrument also
uses a dot matrix display so I had to write all the display drivers and
communication drivers in low-level code. As there was no math's co-processor
on the microchips when I designed this instrument. Got it easy today… Still
being sold in RS Catalogue some fifteen years later that's how good it
still is.
|