Sooner or later, any novice electronics engineer, if he does not give up his experiments, will grow to circuits where it is necessary to monitor not just currents and voltages, but the operation of the circuit in dynamics. This is especially often needed in various generators and pulse devices. There is nothing to do here without an oscilloscope!

A scary device, right? A bunch of pens, some kind of buttons, and even a screen and nifiga it is not clear what is here and why. Nothing, we'll fix it now. Now I will tell you how to use an oscilloscope.

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In fact, everything is simple here - an oscilloscope, roughly speaking, is just ... a voltmeter ! Only a cunning one, capable of showing a change in the shape of the measured voltage.

As always, I will explain with an abstract example.

Imagine that you are standing in front of a railway, and an endless train consisting of exactly the same carriages rushes past you at a breakneck speed. If you just stand at them and look, then you will not see anything but blurry garbage.

And now we put a wall with a window in front of you. And we begin to open the window only when the next carriage is in the same position as the previous one. Since our cars are all the same, you do not need to see the same car at all. As a result, pictures of different but identical cars will pop out in front of your eyes in the same position, which means that the picture will seem to stop. The main thing is to synchronize the opening of the window with the speed of the train, so that when the car is opened, the position of the car does not change. If the speed does not match, then the cars will “move” either forward or backward at a speed depending on the degree of desynchronization.

A stroboscope is built on the same principle - a device that allows you to examine rapidly moving or rotating horseradish. There, too, the curtain quickly opens and closes.

So, an oscilloscope is the same stroboscope, only an electronic one. And he shows not the cars, but periodic changes in voltage. For the same sinusoid, for example, each next period is similar to the previous one, so why not “stop” it by showing one period at a time.

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This is done by means of a ray tube , a deflecting system and a sweep generator.

In a ray tube, a beam of electrons hitting the screen makes the phosphor glow, and the deflection plates allow this beam to be driven over the entire surface of the screen. The stronger the voltage applied to the electrodes, the more the beam is deflected. By applying a sawtooth voltage to the X plates, we create a sweep . That is, the beam moves from left to right, and then abruptly returns back and continues again. And we apply the studied voltage to the Y plates.

How an oscilloscope works

Then everything is simple, if the beginning of the appearance of the saw period (the beam is in the extreme left position) and the beginning of the signal period coincide, then in one sweep, one or more periods of the measured signal will be drawn and the picture will seem to stop. By changing the sweep speed, you can achieve that only one period will remain on the screen at all - that is, one period of the measured signal will pass in one period of the saw.

Synchronization

You can synchronize the saw with the signal either manually, adjusting the speed with the handle so that the sinusoid stops, or you can use the level . That is, we indicate at what voltage level at the input you need to start the sweep generator. As soon as the voltage at the input exceeds the level, the sweep generator will immediately start and give us a pulse.

As a result, the sweep generator produces the saw only when it is needed. In this case, the synchronization is fully automatic. When choosing a level, one should take into account such a factor as interference. So if you take a level too low, then small needles of interference can start the generator when not needed, and if you take a level too high, then the signal can pass under it and nothing happens. But here it is easier to twist the handle yourself and everything will immediately become clear.

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Also, the synchronization signal can be supplied from an external source.

Oscilloscope selection

If you are just getting started, then any will suit you. It is highly desirable if it is two-channel. That is, it will have two probes and two Gain twists, for the first and second channels, which allows you to simultaneously obtain two graphs.

The second most important criterion for an oscilloscope is frequency. The maximum signal frequency that it can pick up. I still had enough 1 MHz for more. Those oscilloscopes that are sold in stores already have a frequency of 10 MHz and higher.

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