hi everyone in this video you will learn what is the block diagram and operation of jewel trace oscilloscope in the previous video we have seen jewel beam oscilloscope and it is jewel trace oscilloscope both are different okay if you see the block diagram and explanation you can understand what is the difference between you will be master scope and you will trace oscilloscope see this is the jewel Trace oscilloscope block diagram. So the first channel A and channel B, these two represents two types of signals which you want to display on the CRT screen. This is signal A and this is signal B. In dual beam oscilloscope also, we have displayed two types of signals, channel A and channel B. But the difference is there we have in dual beam oscilloscope. In the Joule beam oscilloscope, you have taken two vertical deflection plates and one horizontal deflection plates. So two vertical deflection plates, one channel is nowhere related to other channels. So two types of vertical deflection plates are simultaneously coming and one horizontal deflection plate has been used and displaying in the CRT screen. But here in the Joule trace oscilloscope. In dual trace oscilloscope, one vertical reflection plate and one set of horizontal reflection plates we have used. Not two vertical reflection plates as in the case of dual beam oscilloscope. That means three vertical reflection plates, one set of vertical reflection plates is sufficient to display both the waveforms from channel 1 and channel 2. Okay, let us see how it is possible how a single set of vertical frame plates is going to be displayed to waveforms from individual channels. Okay, first the input what you are going to see that is coming from channel A first applied to preamplifier and attenuator. Preamplifier and attenuator this is nothing but vertical amplifier and this is also nothing but vertical amplifier. so vertical amplifier is a wideband amplifier consisting of two types of amplifiers internally one is a set input amplifier followed by BJT main amplifier so here that is written as pre amplifier and attenuator vertical amplifier is nothing but this pre amplifier and attenuator which is a wideband amplifier the output of this one before applying to vertical inflection phase must pass through delay line must pass through delay line this is the delay line here also this is the delay line for the second channel The purpose of delay line canceler also we know. What is the purpose of delay line? In order to stop the signal in the vertical plate when compared to the horizontal deflection system. Horizontal deflection system we have three sets of operations are going to be done. Trigger pulse generator, sweep generator and followed by horizontal amplifier. But whereas in the vertical deflection plates we have only horizontal vertical amplifier directly the output is given to the plates. So, to stop the signal until the horizontal reflection system also reaches the same time period. So, we need to stop the signal in the vertical reflection system by taking a delay line. Now the output of this relay line is connected to electronic switch. This type of switch is the Method we have used in the jewel trace whereas this type of switch was not there in the jewel beam oscilloscope. Because switch is not necessary. Because there are two separate vertical deflection plates we have used. But here we have single set of vertical deflection plates. One time it is connected to channel A and one time it is connected to channel B. So electronic switch is connected to channel A and the same electronic switch is also connected to channel B. okay and the output of this electronics which is now following through vertical amplifier nothing but a second stage of vertical amplifier which is nothing but a main amplifier main amplifier also known as a BJT amplifier if you see the vertical amplifier operation you can understand what is the main amplifier BJT amplifier and this pre amplifier stage okay The entire vertical amplifier section has been divided into two parts. One is the FET input amplifier which is connected before the delay lane and this main amplifier or BJT amplifier which is connected after the delay lane. The output of this one is connected to vertical reflection bits. Okay. Now, We will look for this electronic switch. What is the purpose of this electronic switch and how it is going to be operated. I will tell now. Before going to this electronic switch, let us see what are the different blocks encountered in the horizontal reflection system. In the horizontal reflection system, we need a sweep generator followed by horizontal amplifier see sweep generator we have followed by horizontal amplifier these are okay fine but the sweep generator input should be coming from the trigger circuit trigger circuit it has to take the sync pulse from three ways one is internal signal just discussed in the previous cases it can take the input trigger pulses sync pulses from internal signal and the external signal Another one is line supply. Okay, here how many internal signals are there? How many channels are there? How many input signals are there? Two signals. So channel A, it can be from channel A or the same can be also obtained from channel B. So how many are there now? One, two, three and four. So that's why channel A is there, channel B is there, external trigger impulse is there and line supply is also there. This is line supply. Okay, so these are the four different ways that we can get the synchronous signal to the trigger circuit. The output of this trigger circuit is given to sweep generator followed by horizontal amplifier and then given to horizontal deflection plate. Okay, now coming to this electronic switch how it is going to be operated. Electronic switch basically operated into two modes. Electronic switch. operated in two modes one is alternate mode alternate mode and the second one is chop mode chop mode okay so electronic switch is operated in alternate mode and chop mode What is the purpose of electronic switch? Electronic switch's purpose is to select channel A and channel B continuously or alternatively so that whenever the switch is connected to channel A, channel A is displayed in the vertical reflection plate. Whenever the switch is connected to channel B, channel B is displayed on the vertical reflection plates. So, instead of connecting the electronic switch continuously to only channel A, here we are taking two different modes, alternate mode. Alternate mode means in the sweep generator we have sweeps like this. So, in this particular sweep, channel 1 is going to be selected. In this particular sweep channel 2 is selected. In this particular sweep 1 is selected. In this particular sweep channel 2 is selected. That means alternatively the switch selects channel A and channel B depending upon the switch generator output. Hope you understand. Sweep generator is a sawtooth waveform generator. So for the first cycle it selects channel 1. For the second cycle it selects channel 2. And again 1, 2. Like that it selects alternatively the electronic switch selects alternatively channel A and channel B. That's why it is alternate mode. Next one is chop mode. Chop mode is nothing but within the same cycle it selects the channel A and channel B number of times. It selects the channel A and channel B number of times. So very short duration is there for this Electronic switch mode. Okay, I will tell you in the graphical way then you can understand what is the difference between alternate mode and chop mode So as I said here alternate mode channel A is selected in the rising sweep time see here it is the Here it is sweep time Sweep time is ds from here to here and this is retrace time and the next sweep time up to this one this is TR plus TS and again TR plus TS so if you see here first the channel A is selected whenever there's a second sweep starts it is selecting channel B and again channel A channel B like that it is selecting alternatively and coming to the chop mode within the same cycle of the sweep it selects the channel A and channel B for number of times Okay, channel A is having shortest duration, channel B, then it is going and again channel A, channel B. During the soft periods, channel B is going to be selected. Okay, that means chop is nothing but cutting the signal into small pieces. Chop means small piece, chopping. Chopping is nothing but cutting the signal into very small pieces. So that's why the mode is named as chop mode. So, channel A and channel B are selected at a very fast rate so that the switch alternates between the switch selects A and B continuously like a chopper. So, if you go back to this block diagram, you can understand now how signals are going to be selected A and B by the electronic switch. That is okay. If you see the block diagram, we have one mode mode that is XY mode. What do you mean by XY mode? And when this XY mode occurs, suppose if this switch, here is a switch and here it is a switch. Okay, so if this switch is opened and thus this point is connected to this one, this point is connected to this one and this point is connected to this one. Okay, then what happens? Then what happens? See here, in channel A we have given a sinusoidal signal, in channel B also we have given a sinusoidal signal. However, as this switch is having only one signal because there is no connection here. So as this electronic switch is having only the signal coming from channel A, channel A is directly connected to vertical deflecting plates. So vertical deflecting plates are having the signal from channel A because the channel B is directly eliminated from that path. Now channel B where it is connected, channel B output is directly connected to this horizontal amplifier. That means horizontal reflection plates are connected with a signal that is from channel B. So in this type of case what happens? Channel A and channel B both are having sinusoidal signals. Both are having sinusoidal signals. Then the produced waveforms in the CRT screen are known as lisages patterns. In the starting of this oscilloscope concept, I told you that lesages patterns are generated when both horizontal and vertical inflection plates are applied with sinusoidal signals with different phase shift. Depending upon the phase difference between these two signals between channel A and channel B, different types of patterns may occur. Some may be in circular, some may be in a oval shape, some may be in a rectangular shape, different types of shapes will occur depending upon the phase difference between the channel A and channel B. This is the mode called XY mode. Okay, in XY mode, less charges patterns are generated. In XY mode, less charges patterns are generated. In that mode, what happens, both horizontal and vertical reflection plates are operated with sinusoidal signals. Okay, so in this G-L-Trials oscilloscope what we have to understand only one sets of vertical reflection plates and one set of horizontal reflection plates are used and how a vertical reflection plate single set of vertical reflection plates displays both the signals means by using an electronic switch. So electronic switch operates in two different modes. One is alternate mode and another one is chop mode. In alternate mode based on the sweeps. During first sweep period, channel A signal is selected, second sweep channel B is selected and alternatively it selects like that. But whereas in the chop mode, chopping is nothing but cutting the signal into small pieces. So, the samples of signals are selected and again transmitted to the vertical deflection pencil. This is what the electronic switch mode. So additionally we have one more feature that is the XY mode. In XY mode both the plates are operated with sinusoidal signals. In that mode, lesages patterns are going to be generated on the display. What is the purpose of the Lesage's pattern? We have a separate topic there I will tell you. What is the purpose of Lesage's pattern? Lesage's patterns may be like this or circle like this or like this or like this. Different types of patterns may be there. Lesage's patterns depending upon the phase difference. I will tell you what is the purpose of Lesage's patterns in the coming videos. Lesage's patterns purpose is to measure the unknown frequency. I will tell you in the coming videos when this topic comes. This is what the dual trace oscilloscope, some description is also been added in this next three slides. Thank you.