Crystal is piezoelectric device and has a characteristic vibration, and a crystal device is used for the oscillator circuits (Colpitts oscillator or an unstable multivibrator) with frequency accuracy. Colpitts Oscillator. I am doing this with no particular application in mind. The constructional details and operation of a colpitts oscillator are as discussed below. In the last couple days I have been experimenting and learning about crystal oscillator circuits. Firstly, I suggest you to read the article in ARRL Handbook 2015, Chapter 9 – Oscillator Circuits and construction. The crystal in the QCM sensor has a coating for sensing a gas or vapor. Description. Sabaroff’s quartz crystal version of the Colpitts LC oscillator was published in 1937 , and Meacham’s resistance bridge circuit was published in 1938 151. This is a design schematic of a Crystal Colpitts oscillator can be implemented using a transistor and a parallel mode crystal.
The Colpitts oscillator was invented by American engineer Edwin H. Colpitts in 1918.
In this video, I explain how to analyze the Colpitts oscillator, perhaps the simplest single-transistor amplifier. The circuit of Colpitts oscillator is similar to that of Hartley oscillator except the difference that rather than making tapped connection at the inductor junctions, it is made at the capacitor junction. Quartz Crystal Circuit. The circuit shown by the following figure.
Let us first take a look at the circuit diagram of a Colpitts oscillator. Crystal oscillator circuits are generally constructed using bipolar transistors or FETs. This is the figure of the circuit. A Colpitts oscillator consists of two capacitive reactances and one inductive reactance in the tank circuit or feedback network. Colpitts crystal oscillator There is a great number of different types of circuit that can be used for crystal oscillators, each one having its own advantages and disadvantages. Colpitts oscillator works with a combination of inductors and capacitors by forming an LC filter. We can create Crystal Colpitts oscillator using a parallel mode crystal and a transistor. Same as other oscillators Colpitts oscillator consists of a gain device, and the output is connected with an LC circuit feedback loop. One of the most common circuits used for crystal oscillators is the Colpitts configuration as shown below. In this circuit, the crystal is use as an inductance. This project is a Colpitts Crystal Oscillator. Crystal Oscillator Circuit Diagram. in this case also, the frequency od oscillation lies in the range determined by frequencies f s and f p of the quartz crystal. Construction. Figure 2 shows crystal oscillator using Colpitts circuit using BJT. With the Colpitts oscillator the connection between these two capacitors is used as the centre tap for the circuit