These application areas include broadband communications, spectrum spreading, signal masking, etc.We use water pump motors to draw groundwater and fill it in our tanks. These are used in chaotic circuits which are capable to generate oscillations from audio frequency range to the optical band.A surface acoustical wave (SAW) resonator.
Colpitts oscillators are used for high frequency range and high frequency stability.Where Ceq = C1 C2 / (C1 + C2) Applications of Colpitts oscillator The oscillating frequency of the Colpitts oscillator using op-amp is given by
It is then amplified and keeps the network oscillating strongly. The part of the signal across the capacitor C2 is fed to the inverting amplifier. This makes the both capacitor to starts charging and discharging. When the power supply is given to the circuit, there is no signal, but the small noise voltages are amplified by the op-amp. The LC network is placed in a positive feedback of the operational amplifier In the given circuit the op-amp is connected as an inverting amplifier with a high gain as compared with transistor circuit. The figure below shows the circuit diagram of Colpitts oscillator using op-amp. Thus the op-amp provides the basic amplification needed while the feedback network is responsible for setting the oscillator frequency. The tank circuit remains the same as above discussed circuit. In this type of circuit the op-amp is used in amplifier stage instead of transistor. L = 1.25 µH Colpitts Oscillator using Op-amp Therefore the operating frequency equation becomes We know that, for a Colpitts oscillator the operating frequency is equal to the feedback network resonant frequency, i.e., Also determine the value of the inductance if the operating frequency is doubled. Example of a Transistorized Colpitts OscillatorĬalculate the frequency of oscillations of a Colpitts oscillator using a transistor having C1 = C2 = 0.001♟ and L = 5µH. Therefore, for generating fixed frequencies of signals these oscillators are employed in general. This is a difficult task which requires a special large value of variable capacitor. However, it is difficult to get a smooth variation using inductance L, so the capacitances C1 and C2 must be tuned simultaneously in the ratio of 100: 1 to get the variable frequency. Usually these oscillators are tuned by varying inductance or capacitance of the circuit.
The frequency of oscillations in the Colpitts oscillator is given byįrom the above equation we can observe that the Colpitts oscillator is similar to the other LC oscillators except the tank circuit. Thus, at the amplifier output, sustained undamped oscillations are produced. These oscillations are amplified and phase shifted in the transistor amplifier. The oscillations across the capacitor C2 are applied to the transistor at base-emitter junction. Therefore, an AC voltage is developed across the combination of capacitors. Once these are fully charged, they start discharging through the inductor L by settling up damped oscillations in the tank circuit. This causes the collector current to grow up thereby the capacitors C1 and C2 starts charging. When the power supply is given to the circuit, transistor is turned ON by the small noise voltage as a biasing voltage. Each section is responsible for producing 180 degrees phase shift of the AC output voltage so the waveform at the output of this oscillator is like a standard sine wave when the time it leaves from the oscillator.
Similar to the Hartley oscillator, the Colpitts oscillator consists of two major sections namely amplifier section and tank section. Hence the total capacitance of the tank circuit is found by the product over sum rule as applied to the values of the capacitors.
Use tank circuit as timer series#
The C1 and C2 values are selected such that their ratio of the values produces the desired proportionate feedback signal.ĭue to the series arrangement of these capacitors, the ratio of voltage across this arrangement is inversely proportional to their ratio values. This sine wave oscillator tank circuit composed of a single inductor and two series connected capacitors that are grounded at their common connection as shown in figure.
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