A low cost aluminide process for moderate temperature applications. The scrubber may be mounted to the shearer via a compensation mechanism such as a double hinge and link arrangement which maintains relatively static position andor orientation of the scrubber despite the pivoting of the shearer arm in operation. The impulse signal generator, which is electrically linked to the vehicle connector for receiving an impulse signal from the electrical source of the vehicle, includes a signal integral circuit stably generating a rectangular impulse signal. The structure forms a composite diode and provides a high impedance.