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电路见图。220V交流电经变压器降压,D1～D4整流,C_1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,直流电源经趴、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,电源再次向C2充电……电路形成振荡。振荡频率由RP1～RP14调节。将电键K依次接触各
Circuit shown. 220V AC step-down transformer, D1 ~ D4 rectifier, C_1 filter, get + 13.5V 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. The DC power is supplied to C2 via one of 14 adjustable resistor arrays at the bottom of 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. C2 discharge, SCR return to the deadline, the power supply to C2 again ... ... circuit oscillation. The oscillation frequency is adjusted by RP1 ~ RP14. The keys K are sequentially contacted with each other