# 9. Output Devices - Angelina Yang and Ryan Zhou¶

## Group Assignment¶

• Measure the power consumption of an output device.

• Document your work on the group work page and reflect on your individual page what you learned.

## References¶

Richard and David’s group documentation

## Measuring Voltage¶

For this group assignment, we decided to test the power consumption of a servo running simple code which allowed it to rotate 180 degrees in both directions. To do this, we used a multimeter to measure the voltage and current (in milliamps). After measuring both of these, we used the formula W = V * A, where W stands for watts, to get the total power consumption of our servo.

To measure the voltage, we turned the dial on the multimeter to the first option from the left, directly above the off button. Then, one probe of the multimeter was put on the power connection of the conn header, and the other was put on ground.

As the video shows, the voltage reading on the multimeter consistentlyy hovers around ~5V, which is what we will use to calculate wattage later.

Next, we switched the multimeter to measure the current in milliamps. Instead of touching the probes to power and ground this time, we needed to check flow of power from our board to the servo. To do this, we disconnected the power wire between those two and instead connected them with the multimeter. One probe was put on the board’s power connection, and the other probe was put on the servo’s power wire.

From this video, we can see that the average current reading hovers around ~50 mA, or 0.5 amps. Now, using the voltage and current readings we obtained with the multimeter, we can multiply them together. 5V * 0.5A = 0.25 W, so we can conclude that this servo has a power consumption of around 0.25 W.

Last update: March 28, 2024