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这个定时器不能工作,至少工作不可靠。本定时器终端负载为继电器J。因此晶体管V1、V2无需静态偏置。其驱动信号取自电子表峰鸣器的输出,它是一个交变的功率电压音频信号。晶体管V1发射结工作在整流状态,电容器C2为信号耦合电容。C2通过R2/be结正向电阻充电,通过R2//be结反向电阻放电。由于V1发射结的正向电阻≤R2,故C2充电快,放电慢。充电时间常数很
This timer can not work, at least work is not reliable. The timer terminal load for the relay J. Therefore, transistors V1 and V2 do not need to be statically biased. The drive signal taken from the electronic watch buzzer output, it is an alternating power voltage audio signal. Transistor V1 emitter junction work in the rectified state, capacitor C2 is the signal coupling capacitor. C2 through the R2 / be junction forward resistance charge, through the R2 / be junction reverse resistance discharge. Since the positive resistance of V1 emitter junction ≤ R2, so C2 charge fast, slow discharge. Very constant charging time