Utility model content
Present patent application provides the control circuit of one key switching seven-color LED lamp effect, using the characteristic of RC filtering by dutycycleVariable square wave is converted into the analog voltage of voltage variable, the color change lamp effect of control seven, and seven-color LED brightness is with the duty of square waveChange than change, the utility model uses following technical scheme：Including：Button KEY, triode I, triode II, triodeIIIth, LED, filter capacitor C2 and square wave input end, LED negative pole are followed by square wave input end through resistance R7, and LED positive pole connectsPower supply VCC；Power supply VCC output ends are also grounded after the resistance R1, R2, R3, electric capacity C1 of series winding, and resistance R1 two terminates triodeI emitter stage and base stage；The colelctor electrode of the public termination triode II of resistance R2, R3, resistance R3 and the public termination buttons of electric capacity C1The another of KEY, button KEY terminates at the base stage of triode II, and the base stage of triode II connects the colelctor electrode of triode I and electricity through resistance R5R6, another termination base stages of triode III of resistance R6 are hindered, the filtered electric capacity C2 of colelctor electrode of triode III is followed by LED and resistance R7Common port.
Preferably, triode II is NPN type, and grounding resistance R4 is connected between the base stage and emitter stage of triode II.
Preferably, triode I is positive-negative-positive, the emitter stage connecting resistance R1 of triode I high potential point.
Preferably, triode III selects NPN type, and the grounded emitter of triode III, colelctor electrode connect filter capacitor C2 the moonPole.
Preferably, square wave input end is MCU or waveform generator.
The beneficial effects of the utility model：Present patent application utilizes button KEY on off operating mode, control lamp effect drive circuitWith the voltage change of electric capacity C2 negative terminals, PWM ripples and the switching of analog voltage of LED negative pole are realized, so as to switch lighting effectsAnd brightness, the diversity of product is improved, and circuit is carried using conventional component, it is simple and convenient.
Embodiment
This patent includes：LED, filter capacitor C2, square wave input end and lamp effect drive circuit, LED positive pole connectPower supply VCC, LED negative pole is followed by the square wave input end of variable duty ratio through resistance R7, and negative pole passes through with resistance R7 junctionsWire is connected on electric capacity C2 positive pole, forms RC filter circuits, PWM ripples are converted to the simulation of voltage variable using RC filtering characteristicsVoltage, the change of LED brightness is realized, electric capacity C2 negative pole connects controllable lamp effect drive circuit, by controlling electric capacity C2'sNegative pole high-low voltage realizes the switching of RC filtering operations, failure state, realizes the change of lamp effect.
Wherein, square wave input end is MCU or waveform generator, is already belonging to prior art using MCU output PWM ripples, such asDSP, 51 single-chip microcomputers, some circuits such as 555 circuit output PWM ripples can also be used, because the generation of PWM ripples is already belonging to existing skillArt, therefore redundancy introduction is not done.
Wherein, LED includes driving chip and the wicks of RGB tri-, and after LED power supply, internal driving chip can driveThe wicks of RGB tri-, realize seven-color LED light effect, for falling within prior art using the driving chip driving wicks of RGB tri-, herein notMake redundancy introduction.
Above-mentioned controllable lamp effect drive circuit includes：Button KEY, the triode I of positive-negative-positive, NPN type triode II,Triode III, resistance R1, resistance R2, resistance R3, resistance R4, resistance R5, resistance R6, the electric capacity C1 of NPN type, power supply VCC pass throughWire is grounded after resistance R1, R2, R3, electric capacity C1 successively, and the emitter stage of triode I is connected on resistance R1 and power supply VCC connectionPlace, base stage are connected on resistance R1, R2 common point, colelctor electrode connecting resistance R5, R6, and after upper electricity, triode I be in cut-off state, electricSource VCC charges to electric capacity C1.
The base stage of resistance R6 another termination triode III, the grounded emitter of triode III, colelctor electrode connect electric capacity C2'sNegative pole, when upper electric, triode I ends, triode III ends, and equivalent to hanging, the negative pole of seven-color LED is side for electric capacity C2 negative poleRipple, as monochromatic portable lamp effect.
Triode II colelctor electrode connecting resistance R2, R3 common point, base stage connect button KEY and resistance the R5 other end, hairEmitter-base bandgap grading is also connected on grounding resistance R4 both ends, button KEY another terminating resistor R3 and electric capacity C1 common point, when upper with base stageWhen electricity and button KEY access failures, the base stage of triode II, grounded emitter, triode II are also cut-off, and electric capacity C1, which is in, to be continuedCharged state is until capacitance charge is full of；And after upper electric and button KEY is pressed next time, i.e., after button KEY first connects the short timeDisconnecting, electric capacity C1 sparks when button KEY is connected, and the base voltage moment rise of triode II turns on triode II, and threeThe base voltage moment of pole pipe I, which drags down, meets turn-on condition, so the transient switching of triode I, meanwhile, the colelctor electrode electricity of triode IMoment rise, resistance R4, R5 series connection partial pressure rise are pressed, and resistance R3 and button KEY connection will not be by triode II base stageVoltage is dropped to below threshold value, and now the base stage of triode II remains high level, and triode II often turns on；After button KEY disconnects,Resistance R4 partial pressures make triode II base voltage remain high level, and triode I, triode II remain as conducting state, and threeThe base voltage of pole pipe III is high level always, and triode III turns on, so that electric capacity C2 negative pole is conducting to ground, is filtered using RCThe characteristic of ripple is by the square wave of variable duty ratio（PWM ripples）The analog voltage of voltage variable is converted into, the negative pole of LED is the simulationVoltage, the analog voltage level of conversion will not be too high so will not reset seven-color LED, and seven-color LED has seven color change lamps effects and brightDegree changes with the change in duty cycle of square wave, as seven color portable lamp effects.
Under seven color work lighting effects, electric capacity C1 both end voltages are low level, after pressing one-touch KEY again, that is, are pressedKey KEY disconnects after first connecting the short time.After button KEY is connected, due to the characteristic that electric capacity C1 both end voltages can not be mutated, triodeII base voltage moment drops to below threshold voltage, and triode II moments end；The base voltage of triode I rises to electricitySource voltage VCC, triode I end；Due to thering is pull down resistor R4, electric capacity C1 can not now charge, triode II base voltageBelow threshold voltage, triode II often ends；The base voltage of triode III will be moved to below threshold value by resistance R4, R5,Triode III ends；After button KEY disconnects, triode I, triode II, triode III remain in that cut-off state.Electric capacity C2Negative pole equivalent to hanging, the failure of RC filter functions, the negative pole of LED is square wave, and the driving chip inside seven color LEDs can beSquare wave level is high level（I.e. the negative pole of seven-color LED is high level）When, due to positive and negative terminal operating voltage pressure difference is too low can not be normalWork and reset；When square wave level is low level, the driving chip driving first job cColor-cycling inside LED is bright；FromAnd make that seven-color LED is changed into monochromatic burner and brightness changes with the change in duty cycle of square wave, as monochromatic portable lamp effect.
The principle and its effect of above-described embodiment only illustrative present patent application, not for limitation this patent ShenPlease.Any person skilled in the art can all be carried out under the spirit and scope without prejudice to present patent application to above-described embodimentModifications and changes.Therefore, such as those of ordinary skill in the art without departing from the essence disclosed in present patent applicationWith all lamps effect modifications and changes completed under technological thought, the claim that should be asked by this patent is covered god.