Assembled attachment to connect to multimeter in frequency measurement mode (for kits #1-9, 11-14). It works on all brushless motors with exposed rotating magnets.
Please note than this attachment must be connected to multimeter capable of measuring the frequency in Hz; if you do not have one you should consider RPM Measurement Kit #1.
Motor Speed Measurement page provides information on how to use this attachment for RPM measurement.
Uses four standard AA batteries (not supplied).
Additional note:It was recently discovered that while most frequency measurement devices provide satisfactory results, some of them (for example, Radio Shack 42-range multimeter) do not work well with this measurement attachment. They might be not sensitive enough, or require only clean sine/square wave signal (see customer’s review).
We found that some models can register the signal if the output is connected to a load (resistor across the alligator clips), which is now provided with stand alone attachments. However we cannot guarantee that your multimeter will work correctly even with a connected resistor.
Multimeters we sell with the full RPM Measurement Kit #1 were tested extensively and they are guaranteed to work without any additional circuitry.
A. Thomas (verified owner) –
My daughter (4th grade) used the RPM measurement attachment to measure frequency for her motor kit (#13). We had some initial trouble because the multimeter that we had would not register any frequencies. But, the customer service was excellent and helped us to find a solution that worked and saved the science fair project! (In case you were wondering, we put a 150ohm resister in parallel across the multimeter probes, which somehow allowed the frequency measurement to be registered on the multimeter – a more sensitive meter may have done it just fine. I now wish that we had simply ordered the multimeter from this website since it was already confirmed to work properly with the sensor).