operated as switches i e either off or fully conducting or as loads partially conducting to limit the discharge current through lamp 19 small switching transistors having a relatively large on resistance can be used instead it is preferred to limit the charging current and the discharging current to reduce noise in el lamp 19 an el lamp should not be driven from 50 60 hz line current because the frequency is too low for optimal operation of the lamp fig4 illustrates an inverter powered by line current for driving an el lamp at the proper voltage and frequency bridge 41 is a full wave rectifier bridge for converting line current represented by sinusoidal waveform 42 into direct current that is applied to series connected capacitors 43 and 44 the positive side of capacitor 43 is coupled to high voltage rail 45 and the negative side of capacitor 44 is coupled to common rail 46 transistors 47 and 48 conduct alternately under the control of signal generator 49 to produce an alternating current through el lamp 19 each of the embodiments of fig3 and 4 require no more than five pins per packaged die as represented by the circles around connection points in the figures in fig4 the circuit could be implemented with three pins if the rectifying bridge were external this greatly reduces die size and packaging costs power for the signal generator on the order of microwatts for a cmos circuit is derived from the voltage on the series capacitors lamp 19 is floating not resistively grounded the series capacitors provide an ac ground but not a resistive or dc ground note too that one end.