Crystal Oscillator

jojo March 28, 2011 3 Comments
In crystal oscillators, the usual electrical resonant circuit is replaced by a mechanically vi­brating crystal. The crystal (usually quartz) has a high degree of stability in holding con­stant at whatever frequency the crystal is originally cut to operate. The crystal oscillators are, therefore, used whenever great stability is needed, for example, in communication trans­mitters, and receivers, digital clocks etc. A quartz crystal exhibits a very important property known as piezo-electric effect. When a mechanical pressure is applied across the faces...
read more

Hartley Oscillator

jojo February 4, 2014 16 Comments
Hartley oscillator circuit. Hartley oscillator was invented in 1915 by the american engineer Ralph Hartley while he was working for the Western Electric company. The original design was tube based and he got a patent for it in the year 1920. In a Hartley oscillator  the oscillation frequency is determined by a tank circuit comprising of two inductors and one capacitor. The inductors are connected in series and the capacitor is connected across them in parallel. Hartley oscillators are...
read more

Clapp Oscillator

jojo March 28, 2011 3 Comments
  The Clapp oscillator shown in figure. is a refinement of the Colpitt’s oscillator. The single inductor found in the Colpitt’s oscillator is replaced by a series L-C combination. Addition of capacitor Ca in series with L improves the frequency stability and eliminates the effect of transistor parameters on the operation of the circuit. The op­eration of the circuit is the same as that of the Colpitt’s oscillator. As the circulating tank current flows through C1, C2 and C3 in...
read more

Colpitts Oscillator

jojo August 13, 2018 16 Comments
Colpitts Oscillator An oscillator is used to produce electronic signal with oscillating periods. Eg: Sine wave, square wave etc.. Oscillators are broadly classified into two – linear oscillators and non-linear oscillators. As the name implies, linear oscillators are used to produce linear or sinusiodal waveforms. Whereas, non-linear oscillators are used to produce non-linear (non-sinusoidal output waveforms). All types of electronic oscillators use their input voltage to control the oscillation frequency. Linear oscillators are of many types like Negative Resistance...
read more

Tuned Base Oscillator

jojo February 4, 2014 1 Comment
Tuned base oscillator. Tune base oscillator is another type of transistor based LC oscillator where the tuned circuit (tank circuit)  is placed between the base and ground of the transistor. The tuned base oscillator is also called “Armstrong oscillator” after the name of its inventor. The tuned circuit essentially consists of a transformer and capacitor connected in parallel. The circuit diagram of a typical tuned base oscillator is shown in the figure below. Circuit diagram. In the circuit diagram,...
read more

Tuned Collector Oscillator

jojo February 4, 2014 5 Comments
Tuned collector oscillator. Tuned collector oscillation is a type of transistor LC oscillator where the tuned circuit (tank) consists of a  transformer and a capacitor is connected in the collector circuit of the transistor. Tuned collector oscillator is of course the simplest and the basic type of LC oscillators. The tuned circuit connected at the collector circuit behaves like a purely resistive load at resonance and determines the oscillator frequency.The common applications of tuned collector oscillator are RF oscillator...
read more

LC Oscillators and Types

jojo February 4, 2014 2 Comments
LC oscillators. LC oscillator is a type of oscillator where a LC (inductor-capacitor) tank circuit is used for giving the required positive feedback for sustaining the oscillations. The LC tank circuit is also termed as LC resonant circuit or LC tuned circuit. According to the Barkhausen criterion for sustained oscillations, a circuit will sustain stable oscillations only for frequencies at which the loop gain of the system is equal to or greater than 1 and the phase shift between...
read more

Transistor Oscillators

jojo March 28, 2011 7 Comments
Essentials of Transistor Oscillators An oscillator must have the following three elements Oscillatory circuit or element. Amplifier. Feedback network. The oscillatory circuit or element, also called the tank circuit, consists of an inductive coil of inductance L connected in parallel with a capacitor of capacitance C. The frequency of oscillation in the circuit depends upon the values of L and C. The actual frequency of oscillation is the resonant or natural frequency and is given by the expression f...
read more

Oscillator Operation

jojo March 4, 2011 6 Comments
How an oscillator operates ? Related Articles BASIC OSCILLATORY CIRCUITS TRANSISTOR PHASE SHIFT OSCILLATOR NEGATIVE RESISTANCE OSCILLATORS HARTLEY OSCILLATOR To know the basics of oscillators, its frequency stability, types of oscillations, different types of oscillators and so on, use the tag link – OSCILLATORS A feedback amplifier having closed-loop gain, Af greater than unity can be obtained by the use of a positive feedback. This result also satisfies the phase condition and thus results in the operation of an...
read more

Frequency Stability of Oscillators

jojo March 2, 2011 No Comments
Related Posts OSCILLATOR OPERATION BASIC OSCILLATORY CIRCUITS CLAPP OSCILLATOR WIEN BRIDGE BRIDGE OSCILLATOR LC OSCILLATORS AND TYPES Even if an oscillator is set at an initial frequency, it cannot be maintained throughout. They keep on changing either in a uniform way or sometimes erratically.  the term “frequency stability” is used to define the ability of the oscillator to maintain a single fixed frequency as long as possible over a time interval. These deviations in frequency are caused due to...
read more