We explain how Cathode Ray Tubes (CRTs) were invented and how they work, and hook up a few to light them up. They are as intimidating as they are awesome. But did you know that they led to the discovery of the electron, and the birth of a new field, electronics? And of course the invention of the oscilloscope and modern TV! Link to Eric's scope clock design info: https://github.com/schlae/crt-driver Our 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/ Support the team on Patreon: https://www.patreon.com/curiousmarc Buy our merch on Teespring: https://teespring.com/stores/curiousmarcs-store Get more info on the companion site: https://www.curiousmarc.com/ Contact info: null 00:00 Recap of previous episodes and high voltage warning 01:06 High voltage equipment and CRT basics 02:54 Geissler's discovery of the gas discharge tube 03:32 Crookes' discovery of the Cathode Ray Tube 04:41 J.J. Thomson's CRT explanation, electron discovery 06:22 Braun and Whenelt's development of a practical CRT 08:18 Main electrodes of our T527 tube 09:45 Why the cathode is at -4kV below ground 10:35 Why we need a cathode isolation transformer 11:26 First power on 12:04 Deflection plates 13:46 All the electrodes in a modern tube 15:01 How focusing works 16:30 Hooking up brightness 18:04 Displaying shapes! 19:40 Making an oscilloscope 20:57 Powering up a miniature tube 22:00 Large tube, Eric's CRT clock