PASCO Capstone Scope and 850 Signal Generator

See these PASCO Capstone features in action as we use the 850 Universal Interface's output to drive an LRC circuit through a range of frequencies in search of resonance:
- Signal Generator with a frequency sweep
- Fast Monitor Mode
- Scope display
- FFT display

Hi. My name is Andy Spoone.

In this video, we are going to take a look at an LRC setup

with PASCO Capstone and the 850 Universal Interface.

Let's begin by taking a look at our LRC circuit setup.

I am going to be using the UI-5210 circuit board.

On the circuit board I am going to be using the first inductor component,

the first capacitor component, and the second resistor component.

Connected to my 850 interface, in Channel A I have a Voltage Sensor

measuring the voltage across the entire circuit.

In Channel B, I have a Voltage Sensor measuring the voltage across my second resistor.

And my signal generator is attached across the entire circuit.

Now let's take a look PASCO Capstone and getting set up inside of our software.

I am going to begin by going to my Hardware Setup and adding my two Voltage Sensors.

I can do that by clicking on the channel, typing the first few letters of the sensor,

and then confirming it with the Enter button.

So I am going to add my two Voltage Sensors.

I am now ready to go set up my signal generator.

So I am going to click on my Signal Generator, and I will be using Output 1.

I am going to create a single sweep sine wave

that's going to be looking at a range of frequencies across the circuit,

hoping to find the resonating frequency for the LRC setup

somewhere approximately in the middle of my time range.

So let's go and turn on the single sweep.

We are going to be using an amplitude of 3 V.

We are going to start our initial frequency at 1000 Hz,

our final frequency is going to be at 70000 Hz,

over a duration of 25 seconds, in steps of 1 Hz.

Once your signal generator is set up, we can now go ahead and pin that to our screen,

and open up a full-screen Scope beside it.

So let's go ahead and get our Scope set up.

I am going to begin by adding Channel A to my left axis.

I am going to insert a second y-axis and add my Channel B Voltage Sensor.

I am going to go ahead and turn on my trigger.

This will trigger on voltage from Channel A.

I am also going to go ahead and adjust my axis.

So I know that my amplitude max is 3 V.

So I am going to go ahead and adjust both of my y-axis ranges

so that they max out near 3 V.

I am also going to go ahead and adjust my time axis.

Now notice whenever I start adjusting my time axis,

my sample rate is automatically changing along with it.

And what Capstone is trying to do is adjust the sample rate,

so you are getting the maximum number of points to fill up your oscilloscope display.

Now for this particular set up, I am going to be using components that are resonating

approximately around 30-35000 Hz.

So I am going to go and get a sample rate of approximately 5 MHz.

So, as you can see -- approximately there -- I am at a scale of 0 to 0.00008 seconds.

So that's approximately the scale I am going to be using.

The last thing I want to do is change my Record mode from Continuous to Fast Monitor.

This will change the Record button to a Monitor button.

I am now ready to begin monitoring my voltages, so I am going to press the Monitor button,

and I am going to turn my signal generator on.

You'll notice that I instantly have two different waves that come in to view in my oscilloscope.

They begin out of phase with each other. As I approach the resonating frequency,

they go in to phase.

As I go beyond the resonating frequency, they go out of phase with each other,

and my amplitudes begin to decrease.

And we will just wait a second and watch the signal generator run through the entire 25 seconds.

Afterwards there is no signal produced, so you shouldn't see anything in your oscilloscope.

So let's go ahead and turn off our signal generator and stop our monitoring.

I'm going to run through that one more time.

And this time I am going to try to stop it approximately where the resonating frequency is.

So let's begin monitoring and turn it on.

And right as the waves come right in phase with each other, I am going to try to stop it.

And by clicking on the Stop monitor button, that will freeze the data in my oscilloscope display.

So let's go ahead and stop our signal generator also.

Now, ideally, I would be able to also get the information about what frequencies

I am looking at that's causing that resonation.

So I am going to use my FFT display to identify exactly what frequency that is.

So let's open up a second FFT window.

I am going to add Voltage from Channel A to that.

The first thing I want to do is go ahead and tell it to manually adjust the frequency range.

This will disconnect the link between the sampling rate and the frequency range of my FFT display.

By doing that I can now manually zoom in on my frequency axis,

and I want to get that so that it covers the full range of my signal generator.

So 0 to approximately 100000 Hz should do it.

I am also going to go ahead and zoom in on my y-axis,

once again knowing that 3 V is going to be my maximum amplitude.

Now, as you can see, my bin size right now is fairly large,

and it's covering a lot of frequency range.

So it's going to be hard for me to identify exactly what frequency the resonation is happening at.

So I am going to go in to my FFT properties and change my bin size.

So the maximum number of bins is currently 2048.

I am going to increase that to 8192 and confirm that by pressing OK.

I am now able to go ahead and manually increase the number of bins that it's using

by using the Increase and Decrease Number of Bins buttons in the FFT toolbar.

Notice we can also scale the FFT display to fit.

OK, now as you can see, I am starting to have some clear symbol of

exactly where my resonating frequency is.

To confirm what that bin is, I am going to use my Smart tool.

Notice the Smart tool will try to automatically snap to the closest data point.

So, let it go, let it snap to the data point. All right.

So there it tells me that my frequency that I am currently looking at from channel A is 30500 Hz.

If I want to see a couple of extra decimal points there, I can also right-click on the tool,

open up its tool properties, and increase its number of significant figures.

And I can see that it's actually 30518 Hz.

That's pretty close to what I am expecting for this setup.

Obviously, I can try to go through it again.

I can adjust my bin sizes, if we want to try to use that to get a clearer idea

of exactly where that resonating frequency is.

Notice, as I increase my number of bins, I have now got it to a 32300 Hz,

and that's very close to what I expect the theoretical resonating frequency to be for this setup.

Thanks for joining us in this video.

I hope you learned how to set up an LRC circuit for your classroom.