How to do a speed meter (rpm counter) for a regular NSD Powerball:
- Check that your Powerball has a magnet inside. You only have to put it close enough to another magnet.
- Look for an unused jack plug (the one used to connect the phones to the computer) with a long wire.
- Attach the audio cable to the wrist band hole. Leave the majority of the cable at the plug side.
- Make a coil with the enamelled copper wire. Stick it around the top of the Powerball using some tape.
- Strip the audio cable and remove the enamel from the wire. Sold them or join them with some tape. It should look like this.
- Connect the jack plug to the microphone hole.
- Lanch the Matlab code and start your Powerball. (You can download it from Sourceforge)