[volt-nuts] 34401A Why 10M ohm default i/p resistance?

Poul-Henning Kamp phk at phk.freebsd.dk
Thu Apr 10 15:29:44 EDT 2014

In message <5346A952.9080203 at toneh.demon.co.uk>, Tony writes:

>There is no suggestion in the specifications for the 34401A that the 
>accuracy suffers by selecting 10G ohm input resistance on the .1 to 10V 
>range so why would they make 10M ohm the default? 

In addition to the compatibility reasons others have mentioned, it
also protects the input circuits against random elctrostatic fluctuations
if nothing is attached, and it delays things just long enough that
if you attach +100V, it doesn't have to wait for a relay to kick in
before autorange can work.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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