The RPM probe is connected directly to the ignition unit's induction sensor or magnet sensor. The unit amplifies and processes the signal in such a way that the output passes accurate rotational speed pulses to the SparkSwitch RS, which in turn makes the rotational speed (rpm) available for the radio control system's telemetry system.

The connecting lead is simply plugged in between the ignition unit and the induction or Hall sensor. DA engines, in particular, utilise an induction pick-up, and this system collects the signal and amplifies it without placing a load on the signals.

The RPM probe draws power from the SparkSwitch RS.