| The same concept led to his creating almost complete vacuums in thermionic tubes. |
| The basic thermionic tube with three electrodes is called a triode in view of the number of electrodes. |
| The other device was a type of proximity fuze using a photoelectric cell and thermionic amplifier. |
| It consists of a thermionic tube with a cathode, an anode and a third electrode which is called the collector or counter electrode. |
| In the West transistors had long replaced the thermionic tube in audio circuits. |
| This is the fundamental operating principle of vacuum tubes, once called thermionic tubes. |
