The history of a pioneering tube that was developed by Philips Research and that was, next to the magnetron, The most important tube from World War II The radio valve factory of Philips in Eindhoven was the scene of unusual tension and activity in the evening of the 9th of May 1940. The Germans had been building up an enormous armed force near
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the Dutch-German border, and the people in Holland realized that it was only a matter of time before the Germans would invade their country. This threat was in itself enough to give the nice spring evening an almost unreal and un-earthy atmosphere. On top of that, for the past two months the factory had been working frantically to produce an enormous amount of radio valve components for an unknown customer with an unknown application. Duplicates of special machines to make these components had been hurriedly put together and all these components and machines were now loaded into a truck that that same evening left for the Dutch coast with England as destination. When the truck left the gate of the Philips plant nobody knew that hours later, at 5:30 the Germans would indeed invade Holland. Certainly nobody of those workers, who as the sun set waved the truck good-by, could have imagined that that truck was actually carrying components which were vital to their liberation five years later! As by miracle the truck made it to England although the ferry which carried it was bombarded by German airplanes. These dramatic events marked the start of the life of a radio tube that, not only would play an important role in the outcome of the upcoming war, but that also would be the mother of all modern all-glass radio tubes. The EF50 RF penthode constitutes a landmark in the history of the radio tube. Before the EF50, all radio tubes...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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