Tachometer Part 2

After using my bicycle speedometer-tachometer for a while, I decide to test the Schwinn speedometer that I saw on Amazon for $10. Although it uses the same programming values that I show in the table from my earlier Low-cost Tachometer article, it has some differences that I thought I should point out. The maximum “speed” […]

Flywheel Spin-down work measurements

One way to measure the friction on a rotating machine such as an engine or motor is to spin it up and record the appropriate data while it slows down without power. By measuring the time elapsed between two RPM measurements and knowing the moment of inertia, you can compute the lost energy from the […]

Low-Cost Tachometer

  If you need to measure RPM in experimental setups but don’t want to invest a lot of money, consider using a bicycle speedometer. You can get reasonably accurate measurements digitally displayed using an inexpensive ($15) bicycle speedometer. All you need to do is attach a magnet to the rotating part of the device, position […]