These are resonant circuit or tank circuit oscillators. They are commonly use to produced high frequencies as ranging from I MHz to 500 MHz Hence they are also known as RF oscillators. These oscillators are used in RF generators, radio transmitters and receivers. Some popular IC feedback oscillators are of the following types. Hartley oscillator i
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s very popular and is commonly used as a local oscillator in radio receivers. The main advantages of this oscillator is wide range of frequencies and easy to use. Figure shows the circuit of Hartley oscillator. Its tank circuit consists of two coils L1 and L2. The coil L1 is inductively coupled to coil L2 and the combination works as an auto transformer. A coil called radio frequency choke RFC is connected between the collector and the Vcc supply. It acts as load for the collector and also permits an early flow of D. C current but blocks AC current. The feedback between the output and input circuit is accomplished, through auto transformer actions which also introduces a phase shift of 180o. The phase reversal between the output and input voltage occurs because they are taken from the opposite end of the coil L1 and L2 with respect to the tap, which is grounded. It may be observed that the tap on the combination L1 and L2 coils is actually connected to the transistor emitter terminal via ground and through the capacitor CE. As the transistor also introduces a phase shill of 180 °, therefore the total phase shift is 360 ° and hence the feedback is positive. As the capacitor Cc connected between the collector and the tuned circuit permits only the A. C currents to pass to the tank circuit. It means capacitor Cc blocks the D. C current. The capacitor CB is called blocking capacitor it further blocks the D. C current from...
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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