Abstract: A circuit is provided to speed up switching of a capacitively coupled power transistor driven with a signal provided from a pulse width modulator. The speed-up circuit is provided across a buffer amplifier which is in series circuit between the pulse width modulator and the coupling capacitor. The speed-up circuit includes a time delay circuit which is activated when the output of the amplifier goes low. The delay circuit is coupled to actuate a clamp circuit at a predetermined interval after activation. The clamp circuit is connected to the input of the amplifier and, upon actuation, pulls up the voltage at the input of the amplifier so that it is at a level intermediate the extreme values of the pulse width modulator output signal. In a preferred embodiment the timer is a series RC charging circuit and the clamp is a transistor with its base connected to the junction between the capacitor and the resistor.

Abstract: In a capacitor of the wound metallized dielectric type, a section of resistive material is provided on a film forming the metallized dielectric, and this resistive material extends across the film's entire width (the axial dimension of the capacitor). A metal contact for one of the capacitor plates is sprayed on either end of the capacitor so as to touch one end of the section of resistive material, thereby creating a resistive shunt across the plates formed on the metallized film. The section of resistive material is preferably carbon-loaded paper which is secured over an unmetallized area to the film used to make the capacitor. The paper projects beyond either lateral edge of the film so that spraying metal on the ends of the capacitor causes the ends of the paper to be connected to respective capacitor plates.