General purpose Oscilloscope

A general purpose oscilloscope consists of following parts.
 1. Cathode ray tube
2. Vertical amplifier
3. Delay line  
4. Time base circuit
5. Horizontal amplifier
 6. Trigger circuit
7. Power supply.  

1. Cathode Ray Tube
It is the heart of the oscilloscope. When the electrons emitted by the electron gun strikes the phosphor screen of the CRT, a visual signal is displayed on the CRT. 

2. Vertical Amplifier
The input signals are amplified by the vertical amplifier. Usually, the vertical amplifier is a wide band amplifier which passes the entire band of frequencies. 

3. Delay Line
As the name suggests that, this circuit is used to, delay the signal for a period of time in the vertical section of CRT. The input signal is not applied directly to the vertical plates because the part of the signal gets lost, when the delay Time not used. Therefore, the input signal is delayed by a period of time. 

4. Time Base Circuit
  Time base circuit uses a uni junction transistor, which is used to produce the sweep. The saw tooth voltage produced by the time base circuit is required to deflect the beam in the horizontal section. The spot is deflected by the saw tooth voltage at a constant time dependent rate. 

5. Horizontal Amplifier
 The saw tooth voltage produce by the time base circuit is amplified by the horizontal amplifier before it is applied to horizontal deflection plates   

6. Trigger Circuit
The signals which are used to activate the trigger circuit are converted to trigger pulses for the precision sweep operation whose amplitude is uniform. Hence input signal and the sweep frequency can be synchronized. 

7. Power supply:
The voltages require by CRT, horizontal amplifier and vertical amplifier are provided by the power supply block. Power supply block of oscilloscope is classified in to two types 

(1) Negative high voltage supply
(2) Positive low voltage supply 

The voltages of negative high voltage supply is from -1000V to -1500V.The range of positive voltage supply is from 300V to 400V

 Advantages of General Purpose Oscilloscope
 
1.  It provides a graphical display of the amplitude of a signal as a function of time. Hence, it is used to     measure various electrical parameters.
2.  Amplitude of signals like voltage, current, power etc., can be measured by the oscilloscope.
3. Apart from amplitude measurement, it can measure frequency, phase angle, time delay of the signal,      time between two events, and relative timing of two related signals.          
 4. It has an advantage over electro-mechanical measuring devices that it can respond very well to high     frequency signals because it is completely an electronic device.
5.  General purpose CRO's are used for maintenance of electronic equipment and laboratory work.
6.  It can also be used to measure capacitance, inductance, etc.