John wrote: >David mentioned this: > * * * >What do people think of the device? What are you trying to accomplish? As I posted previously: >Let's assume that it is still working exactly the same as it was >when it was calibrated. The calibration values are recorded to >4-1/2 digits. So the uncertainty is greater than the two LSDs of a >3457A. Of course, it is almost certainly not working exactly the >same as it was when it was calibrated, [so its last digit is going >to be uncertain,] which is going to put at least the third LSD of a >3457A in question. So it is good enough for a 3457A only if one is >content with a 3-1/2 digit verification on a 6-1/2 digit instrument. You should be able to rely on it to verify instruments to 3-1/2 digits. Beyond that, you would need something with a smaller uncertainty. Best regards, Charles

My main interest is as a 'sanity check'. I use DMMs for engineering purposes. Shields up: IMO, there are very few applications, other than fundamental physics research, that really NEED 5,6,7, or 8+ digits. I would no more use a multi digit DVM to do what can be done with a differential voltmeter than use a carrier phase tracking GPS to measure for a living room carpet. Shields down. -John ================ > John wrote: > >>David mentioned this: >> * * * >>What do people think of the device? > > What are you trying to accomplish? As I posted previously: > >>Let's assume that it is still working exactly the same as it was >>when it was calibrated. The calibration values are recorded to >>4-1/2 digits. So the uncertainty is greater than the two LSDs of a >>3457A. Of course, it is almost certainly not working exactly the >>same as it was when it was calibrated, [so its last digit is going >>to be uncertain,] which is going to put at least the third LSD of a >>3457A in question. So it is good enough for a 3457A only if one is >>content with a 3-1/2 digit verification on a 6-1/2 digit instrument. > > You should be able to rely on it to verify instruments to 3-1/2 > digits. Beyond that, you would need something with a smaller uncertainty. > > Best regards, > > Charles > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > >

As digits rise, applications are less 'general', but these meters at the outset were mostly for labs, not for servicing. Work in instrumentation: sensors, transducers etc., can use uV precision foremost, accuracy preferred. A diff DVM is ideal but not necessary, a sensitive DMM is a cheaper substitute. http://www.sensorland.com/HowPage078.html At 12:09 PM 8/12/2013, J. Forster wrote: >My main interest is as a 'sanity check'. I use DMMs for engineering purposes. > >Shields up: > >IMO, there are very few applications, other than fundamental physics >research, that really NEED 5,6,7, or 8+ digits. > >I would no more use a multi digit DVM to do what can be done with a >differential voltmeter than use a carrier phase tracking GPS to measure >for a living room carpet. > >Shields down. > >-John Sincerely, Marv Philadelphia, PA