Crystal radios have been around for over 100 years and exist in many different shapes, sizes and complexities. Some are definitely better than others, but wired correctly and connected to a good Antenna and Ground wire system, this simple little AM radio receiver should pull in at least one strong local radio signal for you to listen in to. In dia
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gram 1 you can see the basic layout of the `crystal set`. They are called crystal sets, as the original designs used a special material called galena or pyrite, as the detector element, which picks out the sound wave from the radio wave. These crystals have been replaced with a modern component called a diode, and we`ll get to use one of those as we put this kit together. Signals from your local AM radio stations are traveling through the atmosphere at the speed of light, and they pass through just about everything. These signals hit your antenna wire and induce a small signal current that flows down into the radio`s tuned circuit, and out through the ground wire, to Earth. The coil, L1 and fixed capacitor, C1, form the `tuned circuit` in our project, in conjunction with the antenna/ground wire system, which enables the receiver to select one station`s frequency and reject the rest. This may seem like a limitation on the radio, but once you`ve got this simple receiver going, you can add one or two more parts in order to make a `tunable` version that can tune across part or all of the AM radio band, for just a couple of dollars more. All you have to do is swap several parts of differing values around, (included in your kit, ) until you receive a reasonably strong local AM radio station! Experimenting is half of the fun with these circuits. The frequency selected by this process is comprised of two parts - the `carrier wave`...
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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