Full wave low flicker LED light string

Abstract

A split bridge circuit for rectifying the alternating current house supply into direct current (D.C.), using hi-polar transistor as rectifying devices. Using specified terminals of the bi-polar transistors results in a high forward voltage drop across the transistors (particularly as compared to the voltage drop across diode rectifiers in the prior art circuits), which reduces ripple significantly and lessens, or even eliminates, the need for a series limiting resistor in the circuit.

I claim: 
     
       1. A series wired light string comprising:
 (a) at least 30 light emitting diodes (LED's) connected in electrical series; and 
 (b) a split bridge rectifying circuit for powering the series connected LED's, the split bridge rectifying circuit comprising:
 (i) a first half bridge rectifying circuit formed of two transistors as rectifying devices, using only the emitter and collector terminals of the transistors, with the base terminal not connected, and 
 (ii) a second half bridge rectifying circuit formed of two transistors as rectifying devices, using only the emitter and collector terminals of the transistors, with the base terminal not connected; 
 wherein the series connected LED's are connected between the first and second halves of the bridge rectifying circuit, and 
 wherein the first half bridge rectifying circuit is connected to a first AC plug and the second half bridge rectifying circuit is connected to a second AC plug. 
 
 
     
     
       2. The light string of  claim 1 , comprising 40 LED's connected in electrical series. 
     
     
       3. The light string of  claim 1 , where 35 LED's are connected in electrical series and an optional series resistance of approximately 750 ohms is included in the series light string. 
     
     
       4. The light string of  claim 1 , where the two transistors of the first half bridge rectifying circuit are mounted inside first AC plug and the two rectifying transistors of the second half bridge rectifying circuit are mounted inside the second AC plug. 
     
     
       5. The light string of  claim 1 , wherein the transistors of the first and second split bridge rectifying circuits have a Vcbo of at least 180 volts. 
     
     
       6. The light string of  claim 1 , wherein the transistors of the first and second split bridge rectifying circuits are bi-polar junction transistors. 
     
     
       7. The light string of  claim 1 , further comprising a third pair of rectifying transistors disposed in the middle of the light string, using only the emitter and collector terminals of the third pair of transistors, with the base terminal not connected. 
     
     
       8. A series wired light string comprising: (a) a plurality of light emitting diodes (LEDs) connected in electrical series; and (b) a split bridge rectifying circuit for powering the series connected LED's, the split bridge rectifying circuit comprising: (i) a first half bridge rectifying circuit formed of two transistors as rectifying devices and (ii) a second half bridge rectifying circuit formed of two transistors as rectifying devices; wherein the series connected LEDs are connected between the first and second halves of the bridge rectifying circuit, and wherein the first half bridge rectifying circuit is connected to a first AC plug and the second half bridge rectifying circuit is connected to a second AC plug. 
     
     
       9. The light string of claim 8, comprising 40 LEDs connected in electrical series. 
     
     
       10. The light string of claim 8, comprising at least 35 LEDs connected in electrical series. 
     
     
       11. The light string of claim 8, where the two transistors of the first half bridge rectifying circuit are mounted inside first AC plug and the two rectifying transistors of the second half bridge rectifying circuit are mounted inside the second AC plug. 
     
     
       12. The light string of claim 8, wherein the transistors of the first and second split bridge rectifying circuits have a Vcbo of at least 180 volts. 
     
     
       13. The light string of claim 8, wherein the transistors of the first and second split bridge rectifying circuits are bi-polar junction transistors. 
     
     
       14. The light string of claim 8, further comprising a third pair of rectifying transistors disposed in the middle of the light string.