| As one kind of gas discharge lamp(HID),metal halide lamp develop very fast since it has many advantages such as long life, good colouration and high photosynthetic capacity. Miniwatt metal halide lamp which is mainly used for interior illumination develop rapidly because it's closely bound up with modern life. The ballast is used with gas discharge lamp,which is changing from inductance ballast that is very cumbersome and ineffective to electronic ballast that is very portable and efficient.The ballast studied in this paper is intelligently controlled by sixpenny 8-bit chip microprocessor.With this method, acoustic resonance which is widely occured in miniwatt metal halide lamp can be avoided easily.The ballast has a good many functions such as reliable igniting and fault detections,and its efficiency is as high as 90%.This paper breake with LCpCs initiate mode which is very widely used,but adopt a sort of new style pulse on circuit.The circuit used here can not only ignitely steadly,but also lower the dash current to protect the circuit. Acoustic resonance is always the shackle of Miniwatt metal halide lamp.This paper presents a new circuit which can change voltage alarm into frequency signal. Low-frequency signal of chip microprocessor is changed into dc signal at first,then the dc signal is changed into high frequency driving signal of half bridge by using change-over circuit.Then the ballst will work in ultra high frequency state,which fight shy of frequency section that can cause acoustic resonance.Light changes function which can be uesd for nonce or ENERGY-SAVING requirement,is always outlying technology for the ballast.This paper will use frequency modulation to change lamp power smoothly in very wide precinct. A sort of clock chip is used in the experiment to distinguish light changes moment,and it can not be impacted by dumo of the ballast.
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