The world`s first practical crystal amplifying device, in 1948, and the dawn of the commercially available Transistor Radio in Britain. If I had been an average radio enthusiast or constructor at that time then I would have been coming to terms with the new miniature all glass valves, learning about the possibility of new TV channels or reading
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about how to incorporate strange FM circuitry into the Domestic Wireless set. However, if I had also followed the accounts from America, since its introduction, of this exotic device called a Germanium Triode and had been further tantalized by snippets in the radio press referring to its experimental production by British companies and also harboured a desire to build a circuit using it, what would have been available to me in terms of circuits or guidance First let us put down a few mile posts so we can see exactly where we are in the scheme of things. What had been officially announced in June 1948 by Bell Telephone Laboratories was a Point Contact Transistor. Journals subsequently referred to it quaintly as a Germanium Triode or a Crystal Valve. It had many drawbacks and wayward characteristics but it worked and it paved the way for other devices. Amongst early contenders in the field in the U. K. were British Thompson Houston and G. E. C. both of which appear to have produced point contact transistors in 1948 and there is new evidence from France to challenge the Bell claim that they were the sole inventors (see postscript). In 1951 Shockley at Bell announced a working junction transistor and the following year they were available commercially in pilot quantities in the United States. The junction transistor was a much more predictable beast but its Achilles heel initially was its poor frequency response. However...
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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