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Virtual Lab

VanessaG
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The main objective of this project is to allow users to be able to make measurements on the circuits connected to the Red Pitaya. In order to achieve this, the Red Pitaya would be connected to the internet, whereby users can access the Red Pitaya anywhere, as long as they are connected to the internet.To read more about how this was achieved, click here.

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Like any other oscilloscope and generator, the Red Pitaya offers those functions as well, as shown in the picture above. For both input and output of the Red Pitaya that is used, channels 1 are used for both the input options in this virtual lab.

  • To start off, access the Red Pitaya by the link right here.
    If you cannot access the link, please copy this into your address bar: http://internshipprojects.ddns.net:90

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You will first come across this index as shown above.

  • Click on ‘Generator & Oscilloscope’ like presented in the picture, then click on run.

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You will then see this interface.

  • Here you should first handle the signal input into the circuit, click on ‘Signal generator’ on the bottom right. Where you will then find the settings:

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  • Like mentioned previously, using Channel 1, click on the box right beside it to prompt this channel.
    Here you should enter the values you want, from the signal type, amplitude, frequency, DC offset and Trigger mode.
    An example of an input wave that you can input into the filter would be:

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Bear in mind that the maximum output signal available is 2V peak to peak.

Now to observe the output of the circuit, since it is connected to a band-pass filter with the cut-off frequencies of 2.341 kHz and 1.421 MHz, and a gain of 4 V/V, there are different options of the output, which are stated right below.

Now considering how this is a filter, there is two options depending on the type of signal you have chosen, which are either:

  1. If the input signal you have selected has a frequency in between that range of the cut-off frequencies, the output wave observed will pass through with no problem. Then the measured amplitude should be multiplied by the gain 4, so expect the amplitude to be 4x the original value.
  2. If the input signal you have selected has a frequency outside of the range of the cut-off frequencies, the output wave observed would be close to a flat line, since the frequency will not pass through the filter. 

If you fall into the option 1, feel free to explore with the functions of the ‘Generator & Oscilloscope’, especially make utitlese of the measure function so that you can clearly see the values of the amplitude to verify if the filter had worked correctly.

You can also adjust the range of the graph to alter your view of the wave, just by clicking on the ‘+’ or ‘-‘ button for the X axis and Y axis, which can be seen in the picture below.

 

Another important note to take note of, the probes are set to an attenuation of 1x, so make sure to keep the values of the gain settings as:

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Just to ensure that the readings are accurate

For further understanding, below are some examples of using the virtual lab, there is also a video to show how it is to be used:

  • For an input wave which has a frequency within the pass-band gain:

With a Sine wave, using a voltage of 0.5 Vpp, and a frequency of 100,000 Hz (100kHz)

 

The expected output should thus have a voltage of 2 Vpp, (0.5 * 4) and be a clear sine wave, as shown in titlethe pictures below, you can see that the output voltage is close to as expected, with a value of 1.915 Vpp.

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  • For an input wave which has a frequency outside the pass-band gain:

With a Sine wave, using a voltage of 0.5 Vpp, and a frequency of 1,500,000 Hz (1.5MHz)

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The expected output in this case, should not have a voltage 4x the input value as the frequency will cause the wave to be cut off, and the amplitude would me minimal. As you can see in the picture below. 

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If you would like to find out more about how this project was made click here and here.

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