Hi, I’m Hus.

In this video, we will measure the power supply of the AC Pracbox, first using the onboard meter and then use the oscilloscope and then measure the RMS value, peak value, peak-to-peak value, period and frequency. First, let’s connect our power supply to this AC meter, so we can see what sort of voltage we’re getting from the power supply. Right now, the power supply is set to 12 volts and the power is turned off. Let’s connect the circuit. When we turn on the power supply, we can see that our meter is reading 13 volts and the frequency of about 50 hertz. It’s not showing anything else because there is nothing connected to the power supply. So it’s not drawing any current. Let’s now connect our oscilloscope and see what sort of signal we get.

With our oscilloscope connected, we can see that there is a sine wave signal on the screen. It’s not a perfect sine wave. It is getting chopped a little bit at the top. But we are getting a sine wave signal. Let’s now measure the different values of this power supply. I have already set some measurements at the bottom, so you can see right at the bottom here it says RMS of 13.0, sometimes 13.1. So that matches our power meter on the AC Pracbox. The frequency also matches about 50 hertz, which is what we got from the meter, and that’s what we would expect. Now, I have the max reading here, which is our voltage peak reading, and that’s showing 18.2. Now, this digital oscilloscope, it measures a few things directly. But we’ll also use the cursor in a minute to do these measurements. It’s also showing us peak-to-peak, which is usually just the double of the peak value, which we’re getting 36.4. And the period is showing 20 milliseconds, which if we do the calculation of one over time, we’ll get 50 hertz in frequency.

Let’s look at the horizontal and vertical scales on the oscilloscope, so we can calculate the peak value and the peak-to-peak value, and also the period using the scales. So the voltage scale, or the vertical scale, we’re seeing five volts per division. And we have this grid here, so that’s five, that’s 10, that’s 15, and it’s almost in the middle. So I would say about 17.5, 18 volts for the peak value. If we double that, we can go from top to bottom and that’ll give us the peak-to-peak value. So that’s our vertical scale. If we look at our horizontal scale, that’s five milliseconds per division. So if we start off from this one here, that’s five, 10, 15, and 20. And then the signal starts again. So that’s our 20 milliseconds, which then gives us the period of 20 milliseconds. One divided by 20 gives us the frequency of 50 hertz. Let’s now activate the cursors so we can measure the peak value and the peak-to-peak value and the period, using the cursors on the oscilloscope. Right now, our vertical cursor is active, so if I move the cursor, it’s tracing our signal.

So I’ll start off where the signal is zero. And then I’ll pick the other side, which is going to full sine wave, which is here. And right here, that’s showing us 20 milliseconds. And over here as well, it’s showing us 20 milliseconds. If I want to measure half the cycle, I can move one of the cursors on half the cycle, and I’m getting about 9.9 milliseconds or about 10 milliseconds, which is our half cycle. Let’s now shift to the horizontal cursors. Right now, I am on the middle cursor, which is set to zero volts. So that’s now set to zero volts, cursor A, and if I then activate cursor B, I can then move that to wherever I need. So if I go right at the top, that will give me the peak reading.

So if I go to the top, I’m getting roughly 18 volts, which is what our measurement was, about 18.4. I can also change that to peak-to-peak. So let’s try and change that to peak-to-peak. And my peak-to-peak measurement is showing 36.3 volts, which is what our measurement is, about 36.4. I hope you enjoyed this video of measuring the power supply of the AC Pracbox using the oscilloscope. If you have any questions or feedback, please feel free to contact us. Thanks for watching.