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振荡电路工作过程如下: 按下电源开关ISW1后,+300 V的直流电压经开关变压器TR1的初级绕组(⑥～④脚)加至开关管BG1的源极;同时该电压经过启动电阻R3(130 kΩ/2W)加至UC3842⑦脚,为其提供启动电压;当UC3842得到启动电压后(该电压必须高于16 V,电路才被启动),内部的振荡器即进入工作状态。R3(130 kΩ/2 W)、C12组成延时电路,只有当C12充电0.5～1 s(秒钟)后,UC3842的启动电压才会达到16 V。UC3842开始工作后,从其⑥脚输出方波信号(如图3所示)通过R7
The working process of the oscillation circuit is as follows: After the power switch ISW1 is pressed, the DC voltage of +300 V is applied to the source of the switch BG1 through the primary winding (⑥ ~ ④) of the switch transformer TR1; meanwhile, the voltage passes through the start resistor R3 kΩ / 2W) to the UC3842 ⑦ pin to provide the starting voltage; when the UC3842 get the starting voltage (the voltage must be higher than 16 V, the circuit was started), the internal oscillator into the working state. R3 (130 kΩ / 2 W), C12 form the delay circuit, only when C12 charge 0.5 ~ 1 s (seconds), UC3842 start-up voltage will reach 16 V. UC3842 began to work, from its ⑥ foot output square wave signal (shown in Figure 3) through the R7