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电路见图。220V交流电经变压器降压,D1～D4整流,C1滤波,获得+13.5V直流电压。单向可控硅SCR和R1、R2、RP1～RP14、C2组成驰张振荡器电路。R2为SCR控制极提供触发电流,直流电源经R1、C2及C2下端的14组可调电阻阵列中的一支到地,向C2充电。当C2端电压上升到可控硅SCR的正向转折电压时,SCR突然导通,C2通过SCR的导通电阻迅速放电。C2放完电,SCR恢复截止状态,电源再
Circuit shown. 220V AC step-down transformer, D1 ~ D4 rectifier, C1 filter, get +13.5 V DC voltage. Unidirectional thyristor SCR and R1, R2, RP1 ~ RP14, C2 composed of relaxation oscillator circuit. R2 provides the trigger current for the SCR control electrode. DC power is supplied to C2 through one of the 14 adjustable resistor arrays at the bottom of R1, C2 and C2. When the C2 terminal voltage rises to the thyristor SCR forward transition voltage, SCR sudden turn-on, C2 through the SCR on-resistance rapid discharge. After C2 is discharged, the SCR is turned off and the power supply is restarted