《报警警笛电路》word版.doc

报警警笛电路图本文从EEPW电路图中为您整理了单音故障报警器、警察汽笛、玩具警笛、高响度警音发生器、120db扫频式警声电路这5款报警警笛电路图。具体详情见下：一单音故障报警器二警察汽笛This circuit produces a sound similar to the police siren.It makes use of two 555 timer ICs used as astable multivibrators. The frequency is controlled by the pin 5 of the IC.The first IC (left) is wired to work around 1Hz. The 47uF capacitor is charged and discharged periodically and the voltage across it gradually increases and decreases periodically.This varying voltage modulates the frequency of the 2nd IC. This process repeats and what you hear is the sound remarkably similar to the police siren.Two presets VR1 and VR2 are provided to vary the siren period of repetition and the tone of the siren.By varying VR1 you can set how fast the siren changes from high freq. to low freq.VR2 sets the siren frequency. Adjust VR1 and VR2 to suit your taste.三玩具警笛该电路可做得足够小以便放在玩具内。它是一个用单结晶体管组成的多谐振荡器，R2和C2决定音调频率。按下按钮SW1时，C1充电，于是R2、C2连接处的电压上升，使振荡频率逐渐升高。当释放SW1时，C1将缓慢放电，导致振荡频率按比例地下降。每隔2s按一次SW1，即可产生警笛的声音。四高响度警音发生器本警音发生器电路简单，工作性能稳定可靠，工作电压6V-12V，适合在汽车、摩托车上作警笛使用。本电路主要由发声集成电路KD9561和开关集成电路TWH8778组成，工作时，由KD-9561输出警音信号，经TWH8778大电流开关集成电路处理放大后，推动扬声器发出洪亮的报警声。元器件选择：IC用KD-9561发声IC，也可以选用KD-9562发声IC，按要求接线使之发出警音报警信号。IC2选用TWH8778开关电路，当电源电压为12V时，喇叭BL应选择8、3W以上的扬声器或专用号筒式扬声器，限流电阻R1的阻值300510，DW选用3V稳压管，VD为电路保护二极管，可以选用1N4001。五120