#Marco-Reps #metrology #precision #toread #electronics video on an 0.1-ppb-resolution Guildline Model 9930 direct-current resistance comparator from the 01960s, specifically November 24, 01969, according to the light-beam galvanometer inspection card. At 2'21" there’s a very alarming CERN slide, “The availability of magnetic materials has been declining over the years.
As of 2024 the assembly can be produced, but there is no replacement yet for the obsolete radial shield material (Nanophylm).” #collapse
The key here is that numbers of transformer windings “don’t have temperature coefficients or long-term drifts”, so they’re accurately ratiometric in a way that’s stable until and unless you bend the wire.
Guildline gave him the service manual, SM9930-H-00.
Internally it has an ovenized Weston cell in a test tube, which is used with a second light-beam galvanometer for feedback control of a 50mA current through a critical precision resistor, which is wire wound around a several-kilogram cylinder of brass; the soldered connections to the manganin (?) wires are stuck into a hole deep inside the brass to reduce possible thermal EMFs.
The nanovolt amplifier is a pair of antiparallel photocells powered by a lightbulb whose light is deflected by a third mirror galvanometer, this one 3.6kΩ.
on 02025-09-28Spinogy X30 5kW CNC Spindle + LinuxCNC EtherCAT Rigid Tapping! #Marco-Reps #video #toread
on 02024-11-22#Marco-Reps #video #toread on #precision #metrology power supplies #electronics #hardware
on 02024-11-12#Marco-Reps #video on #precision #metrology for evaluating his open-source ADR1000 voltage standards. He ends up #3D-printing #flexures out of ASA for its low creep to preload copper-on-copper rotary-switch contacts to try to keep oxidation down. His stator contacts are bare copper on an aluminum PCB. #electronics #hardware
on 02024-11-12#Marco-Reps #video of laser engraving with a 60-watt Q-switched ComMarker B4 fiber laser, with working settings for different materials, including color on stainless and titanium. Lots of iridescent colors. He also uses it to remove rust from a steel piston, to cut a stainless WLCSP-16 solder-paste stencil for reballing an ICE40, to weld plastic, to spot-weld stainless sheet, to weld nickel strip onto a lithium-ion battery, to weld a copper ring onto a low-carbon steel hermetic feedthrough (intermetallic laser welding), and most astonishingly, cutting 2mm steel sheet.
on 02024-11-12