The E1T tube is a marvel of the vacuum tube era. It was over 40 times faster than the dekatron tube and displayed the result directly. The E1T tubes were used mostly in scalers used in nuclear physics research . If you want to learn more about the tube check this page : http://www.dos4ever.com/trochotron/TROCH.htmlThe tube needs a bit of electronics to work : the reset circuit and the bias and feedback circuits . It also needs high voltage (300V) and the heater voltage (6.3V) . There are several designs of the E1T tube testers on the internet , but all of them require powering them from external , high voltage power supplies. To make it a bit simpler I designed a self contained tester which has all necessary electronics on one board. All it needs is a 20-24V DC power supply.