In this blog we will experiment with vacuum tube logic gates. We will be using low voltage so it is totally safe.
We will use a 6al5 twin diode tube. In the circuit below shows how to use it as semiconductors diodes but it’s very same as for vacuum tubes.
Single diode tube symbol 
circuit diagram
Simply wire positive and negative 5v through 6.3v ac or dc to the heaters. Use plate pins as the anode.
Circuit Simulator