The Clapp oscillator is an LC oscillator which has one inductor and three capacitors in its tuned circuit that selects the frequency of oscillation. The oscillator was designed by James Kilton Clapp in 1948. It is also known as the Gouriett oscillator. This oscillator has a very good frequency stability.
Clapp Oscillator Testing
Working of a Clapp Oscillator
The Clapp oscillator is similar to the Colpitts oscillator except that it has an additional capacitor in the tank circuit. This additional capacitor is connected in series with the inductor. The capacitors C1, C2 and C3 form the voltage divider network that determines the amount of feedback, which is given to the input of the transistor. It also provides the 180 degrees of phase shift needed for sustained oscillations. The frequency of the Clapp oscillator is varied by changing the value of capacitor C1. The frequency can be varied only over a narrow band of frequencies.
The Clapp oscillator is similar to the Colpitts oscillator except that it has an additional capacitor in the tank circuit. This additional capacitor is connected in series with the inductor. The capacitors C1, C2 and C3 form the voltage divider network that determines the amount of feedback, which is given to the input of the transistor. It also provides the 180 degrees of phase shift needed for sustained oscillations. The frequency of the Clapp oscillator is varied by changing the value of capacitor C1. The frequency can be varied only over a narrow band of frequencies.
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Clapp Oscillator Circuit
Frequency of the Clapp Oscillator
The frequency of the Clapp oscillator is determined by the series resonance of the inductor L and the capacitor C1. The capacitor C1 is almost 4 times smaller than the capacitors C2 and C3. This combination of the voltage divider network improves the stability of the oscillator more than the Colpitts oscillator. The C1 forms a series tank circuit with the inductor and the capacitance becomes smaller with increase in frequency and vice-versa. It forms the dominant frequency determining component along with the inductor. The C1 is selected according to the frequency of choice and the amount of net capacitive or inductive reactance produced.
The frequency of oscillation in a Clapp oscillator is determined by the formula,
F0 = 1/2π✓1/L(1/C1+1/C2+1/C3)
The frequency of the Clapp oscillator is determined by the series resonance of the inductor L and the capacitor C1. The capacitor C1 is almost 4 times smaller than the capacitors C2 and C3. This combination of the voltage divider network improves the stability of the oscillator more than the Colpitts oscillator. The C1 forms a series tank circuit with the inductor and the capacitance becomes smaller with increase in frequency and vice-versa. It forms the dominant frequency determining component along with the inductor. The C1 is selected according to the frequency of choice and the amount of net capacitive or inductive reactance produced.
The frequency of oscillation in a Clapp oscillator is determined by the formula,
F0 = 1/2π✓1/L(1/C1+1/C2+1/C3)
Frequency of Clapp Oscillator
Advantages of Clapp Oscillator
The Clapp oscillator has higher frequency stability than the other types of LC oscillators.
It provides a higher Q factor, high L to C ratio and lower circulating currents.
It can be finely tuned to a specific frequency, although the tuning range is limited.
It is similar to the Colpitts oscillator and can be easily implemented.
The Clapp oscillator has higher frequency stability than the other types of LC oscillators.
It provides a higher Q factor, high L to C ratio and lower circulating currents.
It can be finely tuned to a specific frequency, although the tuning range is limited.
It is similar to the Colpitts oscillator and can be easily implemented.
Applications of Clapp Oscillator
It is widely used as an LC oscillator in communication receivers.
It is used as a variable frequency oscillator in radio transmitters.
It is used as a carrier oscillator in radio toys and gadgets.
It is widely used as an LC oscillator in communication receivers.
It is used as a variable frequency oscillator in radio transmitters.
It is used as a carrier oscillator in radio toys and gadgets.
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