2171S Speed Sensor Kit

The 2171S Speed Sensor is a hall effect sensor embedded in a bracket with a matching magnet. Its open collector output provides four pulses per motor revolution at a 50% duty cycle as utilized by the Hairball.

The Zilla/Hairball combination does work without a speed sensor, but we strongly recommend installing one and configuring the Hairball to use it in order to help protect your motor from damage.

The Hairball requires a speed sensor such as this one in order to enable the tachometer drive output, motor over-speed and/or the stall detect motor protection options. If you are using reversing contactors then a sensor like this one is required to insure that the Hairball inhibits direction changing when rolling too fast for safe reversing.

Most motors will require drilling and tapping the end of the shaft and some machining of the end bell or a custom support bracket to make this sensor fit. Despite the work required, we feel this is the best and most reliable solution for a speed sensor on your motor. This is the same sensor that came on the Sparrow EV and will fit Sparrow motors with no modification.

This kit comes with 6 feet of cable, connector, cable clip, mounting screws and magnet.