Method and apparatus for driving neon tube to form luminous bubbles and controlling the movement thereof

摘要

According to the present invention, a portion of an applied commercial AC supply (60 Hz) is rectified, filtered and a controllable oscillator in a pulse width modulator chip serves as a signal generator which has both duty cycle and frequency control adjustments. An output signal is coupled via an impedance matching circuit to the input primary winding of a signal transformer having a pair of secondary windings which drive a pair of tandem connected electronic switches which, in turn, are connected across a second DC supply which has a high direct current voltage derived from the input AC line voltage (110-120 V AC 60 Hz). A pair of tandem connected capacitors is connected across the DC supply and an intermediate point between the tandem connected electronic switches is connected to one end of the primary winding of a high voltage output transformer and a second intermediate point between the two tandem connected capacitors is connected to the opposite end of the primary winding of the high voltage output transformer so that on alternate half-cycles of the input signal coupled to the signal transformer from the impedance matching transistor switches is used to alternately drive the gate electrode of the electric switches. A series of control sequences for the switches is stored in a memory, and a microprocessor is programmed to selectively retrieve one or more control sequences so as to cause one or more neon tubes to go through a predetermined program of movements. A ground-fault sensing shut-off circuit is connected to one of the output terminals of the high voltage output transformer and includes comparator circuitry which is capable of sensing when a person, for example, touches one of the output terminals of the high voltage output electrode and disable the electronic switches.