Control Systems & PLC's

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Regulator Transistor

Self regulating, no load protected electronic ballast system

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Referring to the FIGURE, there is shown improved self-regulating, no load protected electronic ballast system 10 having power source 12 for actuation of at least one gas discharge tube 66. Gas discharge tube 66 may be a standard fluorescent type system having first and second filaments 68 and 70, respectively. Self-regulating, no load protected electronic ballast system 10 is provided to maintain the output and input power of gas discharge tube 66 at a predetermined value which is substantially constant during operation and substantially constant and independent of electrical component tolerances from one electronic ballast system 10 to another.

In overall concept, improved self-regulating, no load protected electronic ballast system 10 is provided for maximization of efficiency of light output from gas discharge tube 66 with respect to power input from power source 12. Additionally, improved self-regulating, no load protected electronic ballast system 10 provides substantially constant light output within a narrow tolerance range. The light output of gas discharge tube 66 is maintained at a predetermined level which is insensitive to voltage variations, as the output to the gas discharge tube is responsive to a pulsating driving current, the magnitude of which is regulated. As will be seen in following paragraphs, the output voltage of improved electronic ballast system 10 is limited and substantially reduced when gas discharge tube 66 is electrically removed from the circuit.

Of particular importance, electronic ballast system 10 provides a regulation control 17 which eliminates the need for adjusting or pre-selecting transistors of specific gain, in order to provide a relatively constant light output substantially independent of manufacturing tolerances associated with the manufacture of electronic components which form the ballast system. Additionally, the regulation control circuit 17 limits the maximum output voltage to gas discharge tube 66 in response to voltage increases from power source 12 by maintaining the driving current at a predetermined value.

The output voltage is further controlled by the no load protection circuitry 99 which functions to reduce the output voltage below its normal operating voltage when the gas discharge tube 66 is electrically removed from the circuit, either by its failure or by its physical removal from the system. Load protection circuitry 99 also provides isolation between the regulation control circuitry of ballast system 10 and the high voltage discharge of the gas discharge tube 66.

Additionally, the improved self-regulating, no load protected electronic ballast system 10 provides for a frequency control mechanism using the inductive characteristics of inverter transformer 40 and the tank circuit formed by the center tapped secondary winding 160 of transformer 100 and capacitors 132 and 134. This circuit arrangement for frequency control allows for frequency stabilization with the advantage of permitting electronic ballast system 10 to operate in a normal manner without bothersome visual flickering.

Particularly, operation of the gas discharge tube 66 is maintained at minimum current levels, due to the higher efficiency obtained by improved self-regulating, no load protected electronic ballast system 10, thus improving its life characteristics. Of importance to the reliability of system 10 is the minimumization of electrical components coupled with the simplicity of the circuitry associated with ballast system 10. This concatenation of elements has the effect of increasing reliability of improved self-regulating, no load protected electronic ballast system 10 while simultaneously maximizing the operating lifetime for gas discharge tube 66.

Referring now to the FIGURE, electronic ballast system 10 is coupled to a power source 12 for actuating gas discharge tube 66, such includes rectification circuit 16 coupled to power source 12 for establishing a pulsating direct current voltage signal. The output from rectification circuit 16 is coupled to filter circuit 11 for establishing a substantially smooth direct current voltage signal.

The improved self-regulating, no load protect electronic ballast system 10 further includes induction circuitry 15 which is electrically coupled to filter circuit 11 for establishing the magnitude of a pulsating driving current established by switching network 13. As will be detailed in following paragraphs, induction circuitry 15 includes no load protection circuit 99 for generating a voltage across gas discharge tube 66 responsive to the pulsating driving current, and for maintaining the output voltage at a predetermined value when gas discharge tube 66 is not electrically connected to ballast system 10. Induction circuit 15 is coupled to regulation control circuit 17 for maintaining a gain value of switching network 13 to a predetermined level.

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Can I use a transistor to reduce 12~15v to 3v?

something like this?

Sure, you could (with some additional components),
However would probably be easier to use something like a LM317 (which is mentioned in the article you linked to) adjusted to 3volts. Note that a linear regulator drooping from 12-15 to 3 is not going to be very efficient, I hope you don't need much current.

HAM INTERNATIONAL JUMBO - PSU REGULATOR REPLACEMENT - TIP3055