It is a kind of can adjusting brightness of LED lamps and color simultaneously circuitTechnical field
LED technology field is the utility model is related to, more particularly, to a kind of adjustable LED lamp brightness and the circuit of color.
Background technology
People are directed to diversified research multi-functional to LED always, to meet various increasingly to increase in people's life, workLong demand, although existing many LED color changeables or have multiple color simultaneously it is shinny, LED can not be adjusted simultaneouslyColor and brightness, and the regulation circuit of many LEDs is complex, makes the operation of regulation LED also complex.
Utility model content
In view of the shortcomings of the prior art, the purpose of this utility model is a kind of simple operation, can adjust LED face simultaneouslyColor and the circuit of brightness.
To achieve the above object, scheme provided by the utility model is：A kind of adjustable LED lamp brightness and the electricity of colorRoad, including the first LED light group, the second LED light group, first resistor, second resistance, 3rd resistor and NPN triode, described firstLED light group has multiple LEDs to be composed in series with the second LED light group, and power supply connects the first resistor, the first LED respectivelyGroup and the second LED light group, the first resistor connect the base stage of second resistance and NPN triode respectively, and the second resistance connectsGround, the colelctor electrode of the first LED light group connection NPN triode, the emitter stage of the NPN triode are total to the second LED light groupWith the 3rd resistor is connected, the 3rd resistor is grounded.
Further, the operating voltage of second LED light group is more than the operating voltage of the first LED light group.
Further, first LED light group sends warm light, and the second LED light group sends cold light.
The method of work that the utility model also provides：Power input voltage is Vo, passes through the electricity that resistance is R1 first resistorsPress as V1, be then tapped off, it is R2 second resistances that a part of voltage V2, which flows to resistance, and another part voltage VB flows to NPN triodeBase stage as NPN triode signal input, i.e., the input voltage of NPN transistor base is VB=Vo*R2/（R1+R2）, byActed in first resistor and second resistance, the base stage input voltage change of NPN triode is smaller regard as it is constant；
When input voltage Vo is relatively low, the voltage by the second LED light group is VLED2, because the second LED light group is not up toIt starts voltage, and the first LED light group reaches it and starts voltage, and now the first LED light group has reduced-current ILED1 by through NPNIt is R3 3rd resistors that triode, which flows to resistance, then Vo<VLED2+ILED1*R3, the second LED light group is set not work, the first LED light groupIt is luminous, with input voltage Vo rise, gradually risen by the electric current ILED1 and voltage VLED1 of the first LED light group, make theOne LED light group gradually brightens；
When input voltage Vo rises to median, the voltage VLED2 of the second LED light group reaches startup voltage, makes the 2nd LEDLamp group lights, and now, the first LED light group lights simultaneously with the second LED light group；
Continue to raise with input voltage Vo, gradually risen by the electric current ILED2 and voltage VLED2 of the second LED light groupHeight, the second LED light group is set gradually to brighten, then ILED2*R3 is constantly raised, and the resistance R3 of wherein 3rd resistor is constant, is made byThe voltage V3 of three resistance is constantly raised, and V3=R3（ILED1+ILED2）, then constantly dropped by the electric current ILED1 of the first lamp groupIt is low, make the brightness of the first LED light group constantly reduce, voltage VBE=VB- of emitter stage is now flowed to from the base stage of NPN triodeV3, then voltage VBE constantly reduce, when input voltage Vo is increased to setting value, VBE is less than its operating voltage, makes NPN triodeIt is stopped, so that the first LED light group does not work.
By using such scheme, the beneficial effects of the utility model are：Brightness and the color of LED can be adjusted simultaneously,For this programme in low-voltage, only the first LED light group is shinny, and the second LED light group does not work, as voltage raises, shinny firstLED light group constantly brightens, and the second LED light group continues not working until when voltage reaches startup voltage, and two groups of LEDs are simultaneously shinnyAnd send the light of different colours, voltage continues to raise, and combine NPN triodes effect, make the first LED light group gradually it is dimmed extremelyExtinguish, the second LED light group continues to brighten, realizes while adjust color and the brightness of LED, and this programme is adjusted merely byVoltage can be realized while adjust color and the brightness of LED, simple to operate.
Brief description of the drawings
Fig. 1 is circuit diagram of the present utility model.
Embodiment
With reference to specific embodiment, the utility model is described in further detail：
Referring to shown in accompanying drawing 1, the circuit of a kind of adjustable LED lamp brightness and color, including the first LED light group, the 2nd LEDLamp group, first resistor, second resistance, 3rd resistor and NPN triode, the first LED light group have multiple with the second LED light groupLED is composed in series, and power supply connects the first resistor, the first LED light group and the second LED light group, first resistor difference respectivelyThe base stage of second resistance and NPN triode, second resistance ground connection are connected, the first LED light group connects the colelctor electrode of NPN triode,The emitter stage of NPN triode is connected the 3rd resistor, 3rd resistor ground connection jointly with the second LED light group.
Wherein the operating voltage of the second LED light group is more than the operating voltage of the first LED light group, and the first LED light group sends warmLight, the second LED light group send cold light；The resistance R3 of 3rd resistor is 1.8 Ω, and the present embodiment is by setting the resistance of 3rd resistorSo as to set the magnitude of voltage of the first LED light group extinguishing, the resistance of first resistor and second resistance is more than the resistance of 3rd resistor.
The method of work that the utility model also provides：Power input voltage is Vo, passes through the electricity that resistance is R1 first resistorsPress as V1, be then tapped off, it is R2 second resistances that a part of voltage V2, which flows to resistance,（The voltage for flowing through second resistance is V2）, separatelyThe base stage that a part of voltage VB flows to NPN triode inputs as the signal of NPN triode, i.e. the input of NPN transistor baseVoltage is VB=Vo*R2/（R1+R2）, because first resistor and second resistance act on, the base stage input voltage change of NPN triodeIt is smaller regard as it is constant（The excursion that the input voltage of NPN transistor base is VB is 1.4V~2V）；
When input voltage Vo is relatively low, the voltage by the second LED light group is VLED2, because the second LED light group is not up toIt starts voltage, and the first LED light group reaches it and starts voltage, and now the first LED light group has reduced-current ILED1 by through NPNIt is R3 3rd resistors that triode, which flows to resistance, then Vo<VLED2+ILED1*R3, the second LED light group is set not work, the first LED light groupIt is luminous, with input voltage Vo rise, gradually risen by the electric current ILED1 and voltage VLED1 of the first LED light group, make theOne LED light group gradually brightens, in the continuous elevated stage of the input voltage, because the second LED light group not up to starts voltage,Then the second LED light group does not light, but the second LED light group still has voltage with electric current by the way that NPN triode is in work at this stageState；
When input voltage Vo rises to median, the voltage VLED2 of the second LED light group reaches startup voltage, makes the 2nd LEDLamp group lights, and now, the first LED light group and the second LED light group are simultaneously luminous, but now the first LED light group than the second LED light groupIt is brighter；
Continue to raise with input voltage Vo, gradually risen by the electric current ILED2 and voltage VLED2 of the second LED light groupHeight, the second LED light group is set gradually to brighten, then ILED2*R3 is constantly raised（The electricity of 3rd resistor is input to from the second LED light groupPressure constantly rise）, the resistance R3 of wherein 3rd resistor is constant, makes constantly to raise by the voltage V3 of 3rd resistor, and V3=R3（ILED1+ILED2）, because the resistance R3 of 3rd resistor is constant and the electric current ILED2 of the second LED light group is constantly raised, then pass throughThe electric current ILED1 of first lamp group is constantly reduced, and makes the brightness of the first LED light group constantly reduce, now from the base stage of NPN triodeVoltage VBE=VB-V3 of emitter stage is flowed to, because the voltage V3 of 3rd resistor is constantly raised and learns NPN triode from foregoingBase stage input voltage VB can regard as constant, then voltage VBE is constantly reduced, and when input voltage Vo is increased to setting value, VBE is smallIn its operating voltage（The present embodiment sets VBE<During=0.7V, NPN triode is stopped）, NPN triode is stopped,The first LED light group is set not have electric current by so that the first LED light group does not work.
And after the extinguishing of the first LED light group, the continuation of the second LED light group is shinny, and in the continuous rise of power input voltageTo the process of maximum, the second LED light group constantly brightens to most bright.
Embodiment described above is only preferred embodiment of the present utility model, and any form is not done to the utility modelOn limitation.Any those skilled in the art, in the case where not departing from technical solutions of the utility model ambit, in utilizationThe technology contents for stating announcement make more possible variations and retouching to technical solutions of the utility model, or modification is this practicalityNew equivalent embodiment.Therefore all contents without departing from technical solutions of the utility model, the thinking according to the utility model are madeEquivalent equivalence changes, all should be covered by the scope of protection of the utility model.