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Search found 7 matches

by DavidDilaura
December 21st, 2019, 10:23 am
Forum: Low Current Measurements
Topic: Old 640 vibrating capacitor electrometer
Replies: 10
Views: 34359

Re: Old 640 vibrating capacitor electrometer

Hello, I just saw your post about the old Keithley 640. I have never seen any source for the Phillips xl7900 vibrating capacitor. I had long been interested in it, though never had one until I managed to buy the complete 640 itself. Though I have acquired (virtually) all the literature available for...
by DavidDilaura
December 3rd, 2015, 6:58 pm
Forum: Low Current Measurements
Topic: This forum continuing?
Replies: 1
Views: 11471

This forum continuing?

Dale,

Given the disappearance of the Keithley web site (subsumed into that of Tektronix) I wonder whether this forum will be continued or maintained? Or will it be turned into something else?

Regards,
David L. DiLaura
by DavidDilaura
September 5th, 2014, 3:55 pm
Forum: Low Current Measurements
Topic: Old 640 vibrating capacitor electrometer
Replies: 10
Views: 34359

Re: Old 640 vibrating capacitor electrometer

Ms. Brennan,

I am just now (5 September!) seeing your post. I'd be happy to talk with you about an article. You can contact me reliably by e-mail.
Best regards,

David
by DavidDilaura
April 13th, 2014, 12:24 pm
Forum: Low Current Measurements
Topic: Old 640 vibrating capacitor electrometer
Replies: 10
Views: 34359

Re: Old 640 vibrating capacitor electrometer

Pete, Have you seen this video? https://www.youtube.com/watch?v=-V7z5CQFg3U It's a commemoration of the 60 years (60!) of service that Keithley engineer John Yeager offered Keithley and the measurement industry. John was kind enough to contact me (with Dale's help) about the 640 vibrating capacitor ...
by DavidDilaura
August 22nd, 2013, 3:44 pm
Forum: Low Current Measurements
Topic: Old 640 vibrating capacitor electrometer
Replies: 10
Views: 34359

Re: Old 640 vibrating capacitor electrometer

Many thanks to Dale (at Keithley) who put me in touch with a retired (and famous!) applications engineer who worked for many years at Keithley; including the time during which the Model 640 was designed, built, and brought to market. It was, by his account, an arduous process. He was most helpful, e...
by DavidDilaura
August 8th, 2013, 8:46 am
Forum: Low Current Measurements
Topic: Old 640 vibrating capacitor electrometer
Replies: 10
Views: 34359

Re: Old 640 vibrating capacitor electrometer

Dale,

Many thanks for attempting to put me in touch with a retired engineer there. I look forward to, and will certainly appreciate, any help.

Regards,
D.L. DiLaura
by DavidDilaura
August 4th, 2013, 2:11 pm
Forum: Low Current Measurements
Topic: Old 640 vibrating capacitor electrometer
Replies: 10
Views: 34359

Old 640 vibrating capacitor electrometer

My apologies in advance for this long(ish) post and if this isn't the place for my inquires. I used Keithley electrometers 45 years ago when I was an undergrad and graduate student (involving the measurement of photomultiplier tube currents) and became fascinated by the metrology of low current meas...

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