Technology Research On Low Interference To AM-Band For Optiphone With Wide Voltage

Compared with general signal lamp, burst-flashing signal lamp is widely applied to special vehicle (mobile machinery shop,police wagon, fire engine, etc.),road traffic, aviation lamp,etc.because of its small volume,emitting strong flashes in a short time, good signal transmission effect.Switch DC-DC converting part is the core of burst-flashing signal lamp, its design determines various parameters such as operating frequency, voltage range, power dissipation, EMI etc. So it is the emphasis of this research how to realize wide input voltage, low power dissipation, low interference to AM-band.To reduce the interference to AM-band to the greatest extent, one way is to select suitable frequency, the other way is to reduces interference that caused by variation frequency.. Two grades converting is adopted on researching 10-100V wide input DC voltage of signal lamp. The first grade adopts series switching power supply based on synchronous operating mode, greatly reducing variation of frequency. The second grade adopts fly-back booster of autotransformer to supply enough energy to signal lamp bursting, which has simple structure, small volume and fast boosting voltage. The operating mode based on synchronous of frequency and according to period multiple N effectively ensures synchronous of two grades converting and reduces interference that caused by variation frequency. To reduce system power dissipation, the paper research to adopt new patent technology that utilizes on-resistance of diode to detect current,omits power resistance, meanwhile improves precision of current detection.When being light alarm, mode of single capacitor timing is proposed to overcome the disadvantage. For getting many pulse sequences, it is adopted that set many comparative points on saw-tooth waveform, then generate pulse sequences after comparing successively, which increases the accuracy of control mode.When being audio alarm, the design of power amplifier adopts 2×10W TDA2004, which can acquire bigger output power under low input voltage, good low frequency characteristic, high stability, low noise, low distortion. Alarming audio source adopts HT36A4 which is an 8-bit high performance microcontroller specifically designed for music applications.The research of signal lamp has the characteristic of low interference, wide input voltage, stable operation, low power dissipation, etc, which can be applied to various location of needing alarm. These advantages expand the range of the application and the international market, enhance the market competition ability.