EEVblog 1476 - Keithley 515A Wheatstone Bridge TEARDOWN & TUTORIAL

Teardown of the Keithley 515A Megohm Wheatstone bridge, plus a tutorial on how Wheatsone bridges work and their applications.
Manual & Schematic: https://download.tek.com/manual/515A(Model515A).pdf
1960's Daven precision resistor and attenuator catalog: http://www.technicalaudio.com/pdf/Daven/Daven_attenuator_switch_lab_Catalog.pdf
Keithley electrometer teardown: https://www.youtube.com/watch?v=LI_5ANmkVqo

00:00 Keithley 515A Megohm Wheatstone bridge
03:50 - The Magic smoke test
04:00 - Zero check test
04:40 - Standardise calibration step
05:30 - Range calibration
06:21 - Measuring a 200M resistor
09:41 - Confirmation with a Keithley DMM7510 7 1/2 digit multimeter
10:37 - Weatstrong Bridge Tutorial
14:55 - Gaurd traces for high impedance measurement
16:22 - Teardown
28:25 - OUCH!

Forum: https://www.eevblog.com/forum/blog/eevblog-1476-keithley-515a-wheatstone-bridge-teardown-tutorial/

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