The rotation rate of the electrode may be read from the LCD display on the front panel, and the rate may be adjusted using the knob located just below this display . The rotation rate is adjustable over a range from 50 to 10,000 RPM and is accurate to within 1% of the reading on the display. A voltage output signal that is proportional to the rotation rate is available on the front panel. This signal may be used to monitor the rotation rate using an external voltmeter or data acquisition system.