Transformer tap switching power supply for LED traffic signal

A power supply and an array of light emitting diodes (LEDs (36)), the assembly comprising;

• a transformer (T1) having a primary winding and a secondary winding each having a plurality of turns (12 and 14),
• a plurality of taps (16, 18, 20, 22 and 24) for changing the number of effective turns (12 and 14) of one of the windings,
• an array of LEDs (36) for producing a luminous output in response to power supplied by said transformer (T1), and
• a controller (38) for automatically selecting one of said taps (16, 18, 20, 22 and 24) in response to an operating parameter of said LEDs (36) for maintaining the luminous output of said LEDs (36) above a predetermined level,
• said controller (38) including a measurement device (40) for measuring luminous output of said LEDs (36) as said operating parameter.

A power supply and an array of light emitting diodes (LEDs (36)), the assembly comprising;

• a transformer (T1) having a primary winding and a secondary winding each having a plurality of turns (12 and 14),
• a plurality of taps (16, 18, 20, 22 and 24) for changing the number of effective turns (12 and 14) of one of the windings,
• an array of LEDs (36) for producing a luminous output in response to power supplied by said transformer (T1), and
• a controller (38) for automatically selecting one of said taps (16, 18, 20, 22 and 24) in response to an operating parameter of said LEDs (36) for maintaining the luminous output of said LEDs (36) above a predetermined level,
• said taps (16, 18, 20, 22 and 24) being associated with said primary winding and including a voltage regulator (48) between said secondary winding and said controller (38),
• a resistor (50) in parallel with one of said taps (16, 18, 20, 22 and 24).