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/ Support the EEVblog on: Patreon: http://www.patreon.com/eevblog Odysee: https://odysee.com/@eevblog:7 Web Site: http://www.eevblog.com EEVblog2: http://www.youtube.com/EEVblog2 EEVdiscover: https://www.youtube.com/eevdiscover AliExpress Affiliate: http://s.click.aliexpress.com/e/c2LRpe8g Buy anything through that link and Dave gets a commission at no cost to you. Donate With Bitcoin & Other Crypto Currencies! https://www.eevblog.com/crypto-currency/ T-Shirts: http://teespring.com/stores/eevblog #ElectronicsCreators #Teardown #Keithley