The present invention relates to a support frame for a cathode-ray tube which is capable of preventing damage of a corner portion of a support frame circumference in forming of the support frame. The unit includes a receiver for receiving the signal indicative of a speed limit from the transmitting device. A stepped-up voltage during the first phase, in turn, gives an extra boost to, and thereby forces additional charge into, the cardiac tissue cells, and thereby transfers more charge to the membrane of the excitable cardiac cell than if the capacitors were continuously discharged in series.