Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revision | |||
test-and-measurement:analog-discovery-pro-3x50:power-measurement-demo [2022/09/12 15:22] – changed forum.digilentinc.com to forum.digilent.com Jeffrey | test-and-measurement:analog-discovery-pro-3x50:power-measurement-demo [2023/10/18 19:24] (current) – Alyssa Holzer | ||
---|---|---|---|
Line 1: | Line 1: | ||
+ | ====== Power Measurement with the Analog Discovery Pro (ADP3450/ | ||
+ | ~~TechArticle~~ | ||
+ | {{ reference: | ||
+ | |||
+ | ===== Overview ===== | ||
+ | This demo uses the Analog Discovery Pro's Oscilloscope to measure the power of an RC circuit. Because the oscilloscope only measures voltages, a sensing resistor is used with the Oscilloscope' | ||
+ | |||
+ | ---- | ||
+ | ===== Inventory ===== | ||
+ | * Analog Discovery Pro with: | ||
+ | * 3 BNC oscilloscope probes | ||
+ | * A BNC to minigrabber clip cable | ||
+ | * Analog parts and wires (found in the Analog Parts Kit): | ||
+ | * A 470 Ω resistor | ||
+ | * A 4.7 nF capacitor | ||
+ | * A 1 Ω resistor (sensing resistor) | ||
+ | * A breadboard | ||
+ | * WaveForms Installation, | ||
+ | * [[https:// | ||
+ | |||
+ | ---- | ||
+ | ===== Demo Setup ===== | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | == Hardware Setup == | ||
+ | Assemble the circuit under test shown in the image to the right and connect the Oscilloscope probes and Wavegen grippers at the labeled nodes. Because the BNC probes are single-ended and don't support differential voltage measuring, care must be taken to ensure each probe ground clip is connected to the ground of the circuit. | ||
+ | |||
+ | This demo assumes the analog parts listed in the inventory are the ones being used, but it can be recreated with components of different values with adjustments made to the windowing and Math functions. Note that the sensing resistor needs to be small enough to have minimal impact on the behavior of the overall circuit. | ||
+ | |||
+ | </ | ||
+ | <WRAP column half> | ||
+ | |||
+ | {{reference: | ||
+ | |||
+ | {{reference: | ||
+ | | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | ---- | ||
+ | |||
+ | ==Software Setup== | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | Open the //Wavegen// instrument, configuring it to output a 5 V, 20 kHz Sine wave as shown in the image to the right. | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | **Open** the //Scope// instrument. Enable Channels 1, 2, and 3 and adjust the ranges to match the image to the right. Adjust the ranges of each channel to 5 mV/div, 1 V/div, and 1 V/div respectively, | ||
+ | |||
+ | Clicking the " | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | Without leaving the //Scope// instrument, **Run** All Instruments by clicking the button in the upper right corner of WaveForms, which will start the //Wavegen// and the //Scope// instruments at the same time. | ||
+ | |||
+ | What should be seen at this stage, is the voltage drop across the sensing resistor (Ch 1), the voltage drop across the entire circuit (Ch 2), and the voltage drop across the two resistors (Ch 3), as seen in the image to the right. The current across each component can be calculated using the Scope' | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | Because oscilloscopes only measure voltage, some work needs to be done in order to measure power. The // | ||
+ | |||
+ | To add a math channel, click "Add Channel" | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | The power across the resistor can be calculated as well. To do so, the voltage across the sensing resistor is subtracted from the voltage across both resistors (Channel 3), and the result multiplied by the current passing through the resistor. | ||
+ | |||
+ | **Add** another Math channel, this time with the calculation of " | ||
+ | |||
+ | Note: Scope measurement and math channels can be renamed and relabeled in order to clarify what they represent. This can be done by expanding the channel options (the gear icon) and editing the Name and Label properties of the channel. | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | The capacitor power can also be calculated, by subtracting the voltage across both resistors from the total voltage across the circuit and multiplying the result by the current passing through the circuit. | ||
+ | |||
+ | **Add** one last Math channel with the calculation "(C2 - C3)*C1/ | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | Math3 is noisy but by averaging the signals across multiple measurements this can be reduced. To do so, expand the " | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | To see the average value of each power measurement, | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | In the Wavegen, adjust the frequency of the Sine to 50 Hz, adjust the time base of the Scope instrument to 5 ms/div to accommodate the frequency change. Note the changes in the averages in the Measurements panel. | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | ---- | ||
+ | ===== Other Resources ===== | ||
+ | |||
+ | For more guides and example projects for your Analog Discovery Pro, please visit its [[start|Resource Center]]. | ||
+ | |||
+ | For technical support, please visit the [[https:// | ||