Photogate timing does not default to counting RPMs. To set up your software to take the correct readings of a wind turbine, follow the instructions for your software below:

  1. Launch the Graphical Analysis App, then click or tap Sensor Data Collection.
  2. Connect the photogate to Graphical Analysis app.
  3. Set the photogate’s sensor channels. (GDX Photogate only)
    1. Select the Photogate from the list of available sensors.
    2. Once the sensor is connected, click or tap Sensor Channels.
    3. Turn on Gate 1 – Gate State and turn off all other sensor channels.
    4. Click or tap Done.
  4. Set up the data collection mode.
    1. Click or tap the Mode button in the lower left corner of the app.
    2. Change the Photogate Timing Measurement option to Angular Motion (distance, velocity, acceleration)
    3. Change the number of spokes to 6.  (This number is the number of holes in the gear.)
    4. Change the Angle units to Revolutions.
    5. Click or tap Done.
  5. Set up a calculated column to measure revolutions per minute (RPM).
    1. Click or tap Column Option (three dot icon) next to the Velocity column in the data table, and select Add Calculated Column.
    2. Enter Velocity-RPM as the name and rev/min as the units.
    3. Click or tap Insert Expression and select A*X^B.
    4. Change Parameter A to 60. Verify that Column X is Velocity and Parameter B is 1.
    5. Click or tap Apply.
  6. Set up the graph to plot the Velocity-RPM column.
    1. Click or tap the vertical axis label to access the y-axis Plot Manager.
    2. Turn on the Velocity-RPM column and turn off all other columns.
    3. Tap off the box to dismiss the plot manager.

You are now ready to collect data.

  1. Turn on your LabQuest and choose New from the File menu.
  2. Connect the photogate to your LabQuest.
  3. Set the photogate’s sensor channels. (GDX Photogate only)
    1. Tap the photogate sensor meter (GDX: Velocity) and select Sensor Channels…
    2. Turn on Gate 1 – Gate State and turn off all other sensor channels.
    3. Tap OK.
  4. Set up the data collection mode.
    1. Tap the Mode details box in the upper right corner of the Meter screen.
    2. Verify the Mode is set to Photogate Timing, and the Photogate Mode is set to Motion.
    3. Change the object from Vernier Picket Fence to User defined.
    4. Change the User defined distance measurement to 0.166667 rev (≈ 6-1 since there are six holes in the gear making each blocked event 1/6 revolution).
    5. Tap OK.
  5. Set up a calculated column to measure revolutions per minute (RPM).
    1. Tap the Table icon, , to change to the Table screen.
    2. Tap the Table menu and choose New Calculated Column…
    3. Enter Velocity-RPM as the name and rev/min as the units.
    4. Click or tap Select Equation and select AX.
    5. Change Column for X to Velocity.
    6. Change parameter A to 60.
    7. Tap OK.
  6. Set up the graph to plot the Velocity-RPM column.
    1. Tap the Graph icon, , to change to the Graph screen.
    2. Tap the Graph Menu and choose Show Graph > Graph 1.
    3. Tap the vertical axis label and choose the Velocity-RPM column.

You are now ready to collect data.

  1. Connect the photogate your interface, and connect your interface to your computer.
  2. Launch Logger Pro on your computer.
  3. Set up data collection collection.
    1. From the Experiment menu, click Set Up Sensors and select your interface.
    2. Click the dropdown menu button showing the picture of a photogate, and choose the option Set Distance or Length.
    3. Change the Photogate Timing Measurement option to Angular Motion (distance, velocity, acceleration)
    4. Change the object from Vernier Picket Fence to User defined.
    5. Change the User defined distance measurement to 0.166667 rev (≈ 6-1 since there are six holes in the gear making each blocked event 1/6 revolution).
    6. Click or tap OK to exit the dialog box, then close the sensor setup box.
  4. Set up a calculated column to measure revolutions per minute (RPM).
    1. From the Data Menu, choose New Calculated Column.
    2. Enter Velocity-RPM as the name, RPM as the short name, and rev/min as the units.
    3. Enter 60*”Velocity” as the expression.
    4. Click Done.
  5. Set up the graph to plot the Velocity-RPM column.
    1. Click the vertical axis label on the graph you want to show the velocity and choose the Velocity-RPM column.
    2. Delete any unnecessary graphs.
    3. From the Insert menu, choose Meter > Digital Meter to show a meter for the Velocity-RPM column.
    4. Choose Insert select Auto Arrange from the Page menu to quickly adjust the display.

You are now ready to collect data.

If you don’t want to set up the file manually, use this Logger Pro setup file.

KidWind_Turbine_RPMDownload

See also:
How do I measure rotation speed of a KidWind turbine?
KidWind Troubleshooting and FAQs

Published: March 3, 2022. Updated: March 8, 2022.