报警器电(dian)路(lu)图

如图所示(shi)为电(dian)源(yuan)电(dian)压高(gao)、低限报(bao)警(jing)电(dian)路(lu)。该报(bao)警(jing)器(qi)由高(gao)限报(bao)警(jing)电(dian)路(lu)和低限报(bao)警(jing)电(dian)路(lu)两部分(fen)组(zu)成。右侧为低限报(bao)警(jing)电(dian)路(lu)：在电(dian)源(yuan)电(dian)压接近低限(但(dan)仍为正常)情况(kuang)下(xia)，调(diao)节电(dian)位(wei)器(qi)Wz，使556 8脚电(dian)位(wei)稍大于1/3VDD。

当电源电压向(xiang)下偏移使⑧脚(jiao)电位降到小于l/3VDD)时，556 ⑨脚(jiao)便发(fa)生翻转，输出高(gao)电平(ping)(ping)，从(cong)而使低(di)限(xian)告警发(fa)光二极管LED2发(fa)光。同(tong)时，因晶(jing)体(ti)管BG与⑨脚(jiao)相(xiang)连，故(gu)管子饱(bao)和导通，相(xiang)应又使8脚(jiao)钳位于低(di)电平(ping)(ping)。

稳压(ya)管Dw的(de)稳压(ya)值应选择为(wei)(wei)稍(shao)低于2/3VDD值。左侧(ce)为(wei)(wei)高(gao)限(xian)报警电(dian)(dian)(dian)(dian)(dian)(dian)路：调节(jie)电(dian)(dian)(dian)(dian)(dian)(dian)位器(qi)W1，使电(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)在接(jie)近高(gao)限(xian)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(但仍为(wei)(wei)正常)情况(kuang)下，556⑥脚(jiao)(jiao)电(dian)(dian)(dian)(dian)(dian)(dian)位稍(shao)高(gao)于l／3VDD值，此时(shi)(shi)左侧(ce)电(dian)(dian)(dian)(dian)(dian)(dian)路输(shu)出(⑤脚(jiao)(jiao))为(wei)(wei)低电(dian)(dian)(dian)(dian)(dian)(dian)平。当电(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)瞬间(jian)升高(gao)时(shi)(shi)，因(yin)C1两端(duan)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)不能(neng)突变(bian)，即C，的(de)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)相对于556的(de)基准电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(1／3VDD)变(bian)低，则电(dian)(dian)(dian)(dian)(dian)(dian)路发生翻转，⑤脚(jiao)(jiao)输(shu)出为(wei)(wei)高(gao)电(dian)(dian)(dian)(dian)(dian)(dian)平，此时(shi)(shi)高(gao)限(xian)告警二极管LED1发光，告知超限(xian)。

图中A为复(fu)(fu)位开关。按下时(shi)，强(qiang)制(zhi)复(fu)(fu)位，使电路输出(chu)低电平。本电路适用(yong)于在电源(yuan)电压波动时(shi)及时(shi)发光(guang)报警、进(jin)行监视，从而保证(zheng)直(zhi)流(liu)电压稳定度比较高的场合(he)。

报警器电路图