Can the oscilloscope measure the output of the switching power supply?

As long as the output voltage does not exceed the input voltage of the oscilloscope, the oscilloscope can measure the output waveform of the switching power supply, but pay attention to avoid electric shock when using the hot bottom plate, and it is best to use an isolation transformer to improve safety.

The internal oscillation frequency of the switching power supply is often in the tens of kilohertz to hundreds of kilohertz, and there are also megahertz, but there are more modules.

The oscillation frequency has been filtered to DC at the output of the switching power supply, but there is still a small amount of oscillation frequency remaining, that is, the switching frequency ripple.

If you don't turn on the power supply, you can use an oscilloscope to measure the power supply voltage output, and you can see a relatively faint triangle wave of tens of millivolts or larger. It's not very regular and noisy. However, the shape can still be clearly distinguished, a triangle wave is a period, the switching frequency can be calculated, and if you want to calculate the duty cycle, you can measure the proportion of the ascending part (climbing) and the descending part (downhill).

However, since this triangle wave is usually less than one percent of the output DC voltage, it is almost impossible to see the ripple when measured directly with the DC coupling, that is, only a straight line that you see. So you have to hit the AC AC coupling and turn the voltage selection to a few to tens of millivolts per bar.

Due to the high noise and many spikes, the synchronization is often unstable, so it is necessary to adjust patiently.

If you are using a digital oscilloscope, you can add the "average" function, you can choose to use a larger number of averages, if you have a digital oscilloscope up to 4096, the graphics quality will be greatly improved.

If there is a suitable load, it can be connected, such as 10%, 20% or 50% of the rated load, until the full load, under different loads, the frequency remains the same, but the switching frequency ripple changes greatly, you can choose the easy to measure.

The above refers to the switching power supply controlled by PWM, and the frequency will change with the load if it is controlled by PFM.

When measuring a sinusoidal signal, an oscilloscope.

Here's what you do:

1) Turn on the power switch of the early compass to warm up and adjust the switch knob to the appropriate position.

2) Select the switch to the "AC" position, adjust the brightness, focus, and vertical horizontal position.

3) Send the input signal to the input terminal through the probe and adjust the waveform to the appropriate position.

4) Reading: voltage peak-to-peak, e.g. 2um: 2um= V div number of cells The number of probe attenuations, for example, the peak distance of the waveform peak is a grid, and the V div (voltage value per grid) is:

If the attenuation number of the probe is 1 10, then: 2um = 10 =

5) Calculate the amplitude of the AC voltage.

um=, the RMS value of AC voltage u=<>

When measuring a sinusoidal signal, the oscilloscope operates as follows:

1) Turn on the power supply of the oscillator.

The switch is warmed up and the knobs of each switch are adjusted to the appropriate position, 2) select the switch to the "AC" position, adjust the brightness, focus, and vertical and horizontal position;

3) Send the input signal to the input terminal through the probe and adjust the waveform to the appropriate position;

4) Reading: voltage peak-to-peak, such as 2um:

2um= V div number of tiles The number of probe attenuations.

For example, the waveform peak peak distance is grid, the V div (voltage value per grid) is:, and the probe attenuation number is 1 10, then: 2um= 10 =

5) Calculate the amplitude of the AC voltage um=

RMS value of AC voltage u =

Generally, the input voltage of the oscilloscope is up to 250V, which is attenuated by 10 times on the oscilloscope probe, and then the oscilloscope voltage level is selected at 5V so that the signal less than 250V can be measured, if the signal is greater than 250V, the resistance voltage division can be used to limit the input to 250V, otherwise the oscilloscope is not safe.

Ordinary switching power supply is directly 220V into 300V DC, modulation through less than 30V signal control IGBT or other switches, if you want to test this switch signal, directly with the oscilloscope on the line, after the transformer signal, basically can be directly measured through the oscilloscope, just don't forget to choose the attenuation on the pen on the 10 times.

An oscilloscope is a very versatile electronic measuring instrument. It can transform the invisible electrical signal into a visible image, which is convenient for people to study the change process of various electrical phenomena. An oscilloscope uses a narrow, high-speed electron beam that hits a screen coated with a fluorescent substance to create tiny spots of light (this is how traditional analog oscilloscopes work).

Under the action of the measured signal, the electron beam is like the tip of a pen, which can depict the change curve of the instantaneous value of the measured signal on the screen. The oscilloscope can be used to observe the waveform curves of various signal amplitudes with time, and it can also be used to test a variety of different quantities, such as voltage, current, frequency, phase difference, amplitude modulation, etc.

If you are very clear about the circuit of the power supply, you can also measure it directly, 220V AC, and there is no big problem with ordinary meter pens. But it is very important that the reference grounding point of the watch pen is not wrong. In actual use, we generally add an isolation transformer at the power supply of the oscilloscope, so that there is no need to consider the reference point when measuring, and it is convenient to work, of course, this is also not standardized, and the meter pen and the entire oscilloscope may be at a high potential.

When measuring dangerously high voltages, isolated differential probes are necessary.

No, it doesn't. Plug the test lead to the CHL or CH2 input socket and touch the test probe to the test point to see the waveform on the oscilloscope. If the waveform amplitude is too large or too small, the voltage range knob can be adjusted; If the waveform period display does not fit, adjust the scan speed knob.

Under normal circumstances, the oscilloscope itself has a standard square wave signal output port, when the baseline is obtained, the probe can be connected here, at this time the screen should have a sock string square wave signal, adjust the voltage range and scanning time factor beam Yumeng knob, the amplitude and width of the square wave should change, so far the oscilloscope can be put into use after the basic adjustment.

Basic principle. According to the superposition principle, the result of wave confluence has properties that reflect the original state of the wave. Interferometry is based on this.

When two beams of light of the same frequency are superimposed, they produce fringes that depend on their phase difference: when they are in the same phase, they produce enhanced fringes, and vice versa. Between the two cases, streaks of intermediate strength will occur.

These fringes can be used to analyze the relative phase relationship between these two waves. The vast majority of interferometers use electromagnetic waves such as visible light.

Refer to the above content: Encyclopedia - Oscilloscope.

The oscilloscope cannot be used directly to measure the current, and it will be more troublesome to operate, if you are not an old driver, it is not recommended to do so. It is necessary to pass the conversion method to make the measured current pass through the known shunt resistor, and then take the voltage drop on the shunt pure blind resistor as our current signal, after this step, we can use the oscilloscope to test the current.

The role of the oscilloscope:

1. An instrument used to measure the shape of alternating current or pulse current waves, consisting of an electron tube amplifier, a scanning oscillator, a cathode ray tube, etc. In addition to observing the waveform with air current, it can also measure frequency, voltage intensity, etc. All periodic physical processes that can be turned into electrical effects can be observed with an old grinder.

2. The oscilloscope can transform the invisible electrical signal into a visible image, which is convenient for people to study the change process of various electrical phenomena. An oscilloscope uses a narrow, high-speed electron beam to create tiny spots of light when it hits a screen coated with a fluorescent substance. <>

There is a standard demonstration voltage in the oscilloscope, assuming that the standard demonstration voltage of the oscilloscope is 100 volts, turn the vertical amplitude adjustment knob to make the value of the voltage waveform on the oscilloscope 5 grids, then each grid is 20 volts, so after the adjustment, then measure. If the voltage is too small or too large, you should choose a rotary gear that is magnified by 10 times or reduced by 10 times, and the resulting value is divided by 10 or multiplied by 10.

Note: The maximum voltage measured by the oscilloscope is the peak voltage, and the maximum difference between the positive and negative half-cycles becomes the peak-to-peak. The usual 220 volt AC refers to its effective value, and the peak value is to be multiplied!

414。The multimeter can only measure the alternating current of the sine wave, and is powerless against the various pulses in the TV. It is necessary to know whether the line excitation is enough, the amplitude of the synchronization head is insufficient, and the field scanning is abnormal, etc., only the oscilloscope can easily check out.

To be honest, the oscilloscope mainly looks at the waveform, and the pursuit of accuracy is actually not as good as a multimeter, of course, the oscilloscope can also measure the voltage. Due to the influence of vertical accuracy, first adjust the time base and vertical gear so that the waveform occupies the entire screen (so that the accuracy is the highest), and then open the measurement item and select the one you want to measure, such as amplitude:

In addition to voltage, oscilloscopes can actually measure many other parameters of the signal:

Setup on both sides is required.

1) Probe end:

a.The probe needs to be calibrated.

b.Ensure that the attenuation factor of the probe is consistent with the attenuation factor set by the oscilloscope channel.

c.The impedances of the probe and oscilloscope input channels need to match. For example, the SDS1102X-C web link has an impedance of 1mohm. However, some oscilloscopes also have a 50ohm input impedance.

d.The ground clip of the probe needs to be connected to the same ground as the signal being measured.

e.The probe end of the probe needs to be clamped or spotted to measure the point to be measured.

2) On the oscilloscope side, the vertical gear needs to be set so that the waveform fills the screen as much as possible, so that the peaks and peaks measured by the oscilloscope's measurement function are more accurate.