Fluorescent lamp circuit with low voltage supply

Claim 2

An electrical circuit for fluorescent lamps supplied from a low voltage direct current power source characterized by its ability to efficiently function at low temperatures and when supplied by full wave rectified, pulsating, direct current comprising, in combination, a transformer having primary and secondary windings, a fluorescent lamp having first and second spaced electrodes, said secondary winding being connected to said first lamp electrode, a two conductor direct current power source, said second electrode being connected to said power source, a power transistor having a first base and a first interrupted current output, said output being connected to said primary winding, first and second resistors connected in series across said power source constituting a first divider network connected to said first base biasing said transistor toward a conducting state, a driver transistor having a second base and a second interrupted current output, third and fourth resistors connected in series across said power source constituting a second divider network connected to said second base biasing said second base toward a conducting state, and a feedback circuit interconnecting said first interrupted current output to said second base, said second interrupted current output being to said first base whereby said feedback circuit is isolated from said first base to insure reliable oscillation of said power transistor.

Claim 3

In an electrical circuit for fluorescent lamps as in claim 1 wherein said first resistor of said first divider network comprises a positive temperature compensated resistor.

Claim 4

In an electrical circuit for fluorescent lamps as in claim 2, a diode in series with the Positive conductor of said direct current power source interposed in the circuit before said divider networks.

Claim 5

In an electrical circuit for fluorescent lamps as in claim 2 wherein said secondary winding includes terminal leads carrying the full potential output of said secondary winding, a capacitor voltage divider network connected across said terminal leads, a pair of fluorescent lamps each having first and second electrodes said terminal leads each connected to a first electrode.

Claim 6

In an electrical circuit for fluorescent lamps as in claim 2, said fluorescent lamp second electrode comprising a second filament spaced from said first electrode and conductors connecting said second filament across said direct current power supply conductors maintaining said second filament in a heated condition during lamp operation.

Claim 7

In an electrical circuit for fluorescent lamps as in claim 2, wherein said secondary winding includes terminal leads carrying the full potential output of said secondary winding, a capacitor voltage divider connected across said terminal leads, a pair of fluorescent lamps each having first and second spaced electrodes and filaments, respectively, said terminal leads each connected to a first electrode, and conductors connecting said second filaments in series across said direct current power source maintaining said second filaments in a heated condition during lamp operation.

Claim 8

In an electrical circuit for fluorescent lamps as in claim 6, a capacitor connected across one of said terminal leads and a direct current power supply conductor to produce simultaneous ignition of said lamps.

Claim 9

An electrical circuit for fluorescent lamps supplied from a direct current power source comprising, in combination, positive and negative direct current supply conductors, a transformer having a primary winding having first and second leads and a secondary winding having third and fourth leads, a power transistor having a first base, a first collector and a first emitter, said first lead being connected to said positive conductor and said second lead being connected to said collector, said emitter being connected to said negative conductor, a first positive temperature compensated resistor interconnecting said base and said positive conductor, a second resistor connecting said base and said negative conductor, a driver transistor having a second base, a second collector and a second emitter, a third resistor connecting said positive conductor to said second base, a fourth resistor connecting said negative conductor to said second base, a feedback conductor connecting said second lead to said second base through a first capacitor, said second collector being connected to said first base through a second capacitor, said second emitter being connected to said negative conductor, a fifth resistor interposed between said second collector and said positive conductor, a pair of fluorescent lamps each having first and second spaced electrodes and filaments, respectively, said third lead connected to one of said first electrodes and said fourth lead connected to the other of said first electrodes, said second electrodes being connected to said supply conductors, and third and fourth capacitors connected in series across said third and fourth leads, said negative conductor being connected intermediate said third and fourth capacitors.

Claim 10

An electrical circuit for fluorescent lamps supplied from a direct current power source comprising, in combination, positive and negative direct current supply conductors, a transformer having a primary winding having first and second leads and a secondary winding having third and fourth leads, a power transistor having a first base, a first collector and a first emitter, said first lead being connected to said positive conductor and said second lead being connected to said collector, said emitter being connected to said negative conductor, a first positive temperature compensated resistor interconnecting said base and said positive conductor, a second resistor connecting said base and said negative conductor, a driver transistor having a second base, a second collector and a second emitter, a third resistor connecting said positive conductor to said second base, a fourth resistor connecting said negative conductor to said second base, a feedback conductor connecting said second lead to said second base through a first capacitor, said second collector being connected to said first base through a second capacitor, said second emitter being connected to said negative conductor, a fifth resistor interposed between said second collector and said positive conductor, a pair of fluorescent lamps each having first and second spaced electrodes and filaments, respectively, said third lead connected to one of said first electrodes and said fourth lead connected to the other of said first electrodes, said second electrodes being connected to said supply conductors, and third and fourth capacitors connected in series across said third and fourth leads, said negative conductor being connected intermediate said third and fourth capacitors.

Claim 11

In an electrical circuit for fluorescent lamps as in claim 8, a fifth capacitor interposed between said third lead and said positive conductor to insure simultaneous ignition of said lamps.

Claim 12

In an electrical circuit for fluorescent lamps as in claim 8, conductor means connecting said second filaments of said lamps in series across said positive and negative conductors to maintain said second filaments in a heated condition during lamp operation.