31. In an ECO, The screen grid acts as a plate for the triode oscillator. 32. Before 1915, triode vacuum tubes were spherical or shaped like an incandescent light bulb. 33. The triode , however, was a fragile device that consumed a substantial amount of power. 34. This particular example uses six triodes . 35. This eliminated the need for a preamplifier triode in radios, making them cheaper to produce. 36. The first product produced under the trade mark " Eimac " was the 150T power triode . 37. This was driven by a pair of type 4015-A triode valves cooled by air. 38. Lee de Forest placed a screen, added a " grid " electrode, creating the triode . 39. The electronics revolution of the 20th century arguably began with the invention of the triode vacuum tube. 40. Impedance of 1000 to 2000 ohms was common, which suited both crystal sets and triode receivers.
