We repair a classic HP 3478A 5-½ digit voltmeter, and admire its ultra complicated A to D converter.

HP Multislope II ADC patent: https://patents.google.com/patent/US4...

Ian Scott Johnston video on HP 3457 backlight mod:    • No.042 - HP3457A Backlighting Mods  

Blacklight display mod: https://www.eevblog.com/forum/testgea...

LCD protocol reverse engineering: https://www.eevblog.com/forum/project...

OLED mod: https://www.eevblog.com/forum/testgea...

Ken Shirriff's Nanoprocessor reverse engineering: http://www.righto.com/2020/09/hp-nano...

Ken Shirriff’s reverse engineering of the hybrid in Marco Reps’ HP 3458: https://x.com/kenshirriff/status/1448...

Jeff Peletz amazing HP instrument pictures: http://hparchive.com/wallpaper

Stuff that supports the channel:
- Amazon links for the tools I use in the lab: https://www.curiousmarc.com/amazon-links
- Channel merch on Fourthwall: https://curiousmarc-shop.fourthwall.com
- Legacy channel merch on Teespring (I don't have everything transferred to Fourthwall yet): https://teespring.com/stores/curiousm...
- Support us on Patreon:   / curiousmarc  

"Elevator Music" Credit: Crinoline Dreams by Kevin MacLeod

Our lovely sponsors
- PCBWay: fast turn PCBs, https://www.pcbway.com
- Electro-Rent: https://www.electrorent.com
- Keysight: test instruments: https://www.keysight.com
- Samtec: connectors: https://www.samtec.com
- R&D Microwaves: https://rdmicrowaves.com

Get more technical info on the companion site: https://www.curiousmarc.com
Contact info: https://www.youtube.com/curiousmarc/a...