No problem. I was just looking back at the documents wondering if I missed anything. The transformer solution is interesting and I see that the 8508A has a second low voltage transformer (T1). I have no idea if it performs the same function using a different calibration.
On Sat, Oct 31, 2015 at 9:33 AM, Frank Stellmach <[email protected] > wrote: > Todd, > > you already have sent me the appropriate SelfCAL circuitry, but I did not > recognize (understand) it as such! > > I also received a hint from another volt-nuts, John, about the complete > documents for the DATRON 1271 on the KO4BB site, which is very similar, and > also contains a SelfCAL module, being a bit different than the one inside > the 1281. > > The schematics for the 1271, anhow reveal how the transformer inside this > module provides different voltage ratios. The transformer there is labelled > +9.93V, +/-7.23V (that's the main references value), 1.83V, 1.00V and 0.19V. > > These ratios were generated with a precision switch mode / chopper > circuit, and as the ratios on a transformer are very stable, you only have > to measure them once during initial calibration. > > Obviously that is good for ppm ratio accuracy in the SelfCAL procedure. > > So thanks again > > Frank > > > > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
