For a fixed frequency transmitter one commonly used method is to use a resonant quartz crystal in a Crystal oscillator to fix the frequency. For transmitter where the frequency has to be able to be varied then several options can be used. It is often the case for VHF transmitters that it is not possible to operate the crystal controlled or variabl
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e frequency oscillator at the frequency of the final output. Also, for reasons including frequency stability, it is better to multiply the frequency of the free running oscillator up to the final frequency which is required. If the output of a amplifier stage is tuned to a multiple of the frequency which the stage is driven with, the stage is optimised to give a larger harmonic output than that found in a linear amplifier. In a push-push stage, the output will only contain the even harmonics. This is because the currents which would generate the fundamental and the odd harmonics in this circuit (if one valve was removed) are canceled out by the second valve. Note that in these diagrams that the bias supplies and the neutralization have been omitted for clarity. In a real system it is likely that tetrodes would be used as plate to grid capacitance in a tetrode is lower so making the stage less likely to be unstable. The task of many transmitters is to transmit some form of information using a carrier wave. This process is called modulation. There are many types of RF modulation, and the choice of modulation often depends on the type of information being transmitted. For instance, audio information is continuous in time and value, and scaling by a constant (i. e. signal inversion, volume control) is acceptable, so AM and FM transmission work. But for digital communications, the signal is discrete in time and discrete in...
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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