The diagrams below detail the development of a simple modular radio receiver based entirely on circuits and devices studied during the Part IA course on Linear Circuits and Devices. This receiver may not take the market by storm! However, we hope it will help illustrate how the circuits and principles we are studying all c
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ontribute to the art of electronic circuit design. A crystal set does not have a battery. It runs completely from the energy extracted from radio waves it picks up from the antenna. A resonant LC (or tuned) circuit coupled to a large aerial or antenna was used. Many amateur experimenters constructed crystal sets, often with the tuner inductor coil wound on a tubular box or a drinking glass. At this time the semiconductor diode had not been invented, so extracting the audible modulation signal from the transmission relied on the non-linear electrical properties of the `crystal`, typically a piece of coke or galena. In early sets a "cat`s whiskers" - a fine piece of wire - was adjusted by trial and error to make a suitable contact with the crystal. There were many limitations to the crystal set: it needed a big aerial (antenna), an earth connection, the clumsy cat`s whisker, and the weak signal could only be listened to by one person at a time with headphones. Very quickly the crystal set began to be replaced by valve radios with loudspeakers, powered by batteries. In World War II, crystal sets were used by prisoners of war in prison camps to listen to news from home. Much ingenuity went into improvising the necessary components. The design shown here is a little more complex than strictly necessary, but some of the adaptations incorporated make it easier to develop the design, adding amplifiers and other stages as we meet...
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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