Glowing mercury thyratrons: inside a 1940s Teletype switching power supply

1 · Ken Shirriff · Sept. 7, 2018, 4:23 p.m.
We recently started restoring a Teletype Model 19, a Navy communication system introduced in the 1940s.14 This Teletype was powered by a bulky DC power supply called the "REC-30 rectifier". The power supply uses special mercury-vapor thyratron tubes, which give off an eerie blue glow in operation, as you can see below. The thyratron tubes in the Teletype REC-30 power supply give off a blue glow. The orange light is a neon bulb used as a voltage reference. The power supply is interesting, sinc...