Impedance matching circuit for switched alternating current power supplies
AssigneeSingapore Technologies Electronics, Ltd.
InventorsKoh Hock Tan, Kay Keow Quincey Poon, King Pok Lee, Kheng Joo Yeo, See Tee Tan
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Abstract
A traffic light system (10) with an impedance matching circuit (14) for electrically coupling an optical assembly (12) to a switched AC power supply (26) is described. The impedance matching circuit (14) has a matching transformer (20), a first resistor chain (22) and a second resistor chain (24). Each resistor chain (22,24) has an input and an output. Each of the inputs is common with a respective electrical node of the matching transformer (20). Each of the outputs is common with a respective supply node provided by the primary windings (18a) of an input transformer (18) of the optical assembly (12).
Claims17
An impedance matching circuit for matching a switched alternating-current (AC) power supply to an optical assembly, said impedance matching circuit comprising:
- at least one matching transformer electrically coupled to said switched AC power supply;
- a first resistor chain comprising at least one resistor connected in series and having an input and an output, said input being common with an electrical node of said matching transformer, said output being common with a supply node of said optical assembly;
- and
- a second resistor chain comprising at least one resistor connected in series and having an input and an output, said input being common with another electrical node of said matching transformer, said output being common with another supply node of said optical assembly.
An optical assembly for traffic light signaling, said optical assembly comprising:
- a plurality of lighting elements;
- an input transformer having primary windings and secondary windings, said secondary windings being electrically coupled to said plurality of lighting elements;
- and
- an impedance matching circuit electrically coupled to said input transformer, said impedance matching circuit comprising:
- at least one matching transformer;
- a first resistor chain comprising at least one resistor connected in series and having an input and an output, said input being common with an electrical node of said matching transformer, said output being common with a supply node of said primary windings;
- and
- a second resistor chain comprising at least one resistor connected in series and having an input and an output, said input being common with another electrical node of said matching transformer, said output being common with another supply node of said primary windings.
A traffic light system to provide traffic light signals, said traffic light system comprising:
- at least one optical assembly comprising:
- a plurality of lighting elements;
- and
- an input transformer having primary windings and secondary windings, said secondary windings being electrically coupled to said plurality of lighting elements;
- and
- at least one impedance matching circuit electrically coupled to said optical assembly, each of said impedance matching circuit comprising:
- at least one matching transformer;
- a first resistor chain comprising at least one resistor connected in series and having an input and an output, said input being common with an electrical node of said matching transformer, said output being common with a supply node of said primary windings;
- and
- a second resistor chain comprising at least one resistor connected in series and having an input and an output, said input being common with another electrical node of said matching transformer, said output being common with another supply node of said primary windings.
Dependencies are inferred from the claim text.