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这个电路是以由4个1N4148二极管和两个相同容量的电容器组成的电流控制文式电桥为基础绘出的.电流经电流形放大器LM3900馈入桥路.作为这种放大器,应选用β值达10~6优等晶体管,输入电压Vi的微小变化,就可以产生大的频率变化.这个电路的振荡频率直接与控制电流成比例.可以工作于10C——50KC,其电流与频率之间保持比例关系.这个范围内引起频率变化的电流变化是1—10~4μA.建议C值取700PF.运算放大器电压增益要求R_2/(R_1+R_2)>1/3.
This circuit is based on a current-controlled, bridge-type bridge consisting of four 1N4148 diodes and two capacitors of the same capacity.The current is fed into the bridge via the current-rail amplifier LM3900.As this amplifier, a beta value Up to 10 ~ 6 excellent transistor, the small changes in the input voltage Vi, can produce large frequency changes. The oscillation frequency of this circuit is directly proportional to the control current. Can work at 10C - 50KC, the current and frequency to maintain the ratio The relationship between this range causes changes in the frequency of current is 1-10 ~ 4μ A. Recommended value of C to take 700PF. Op amp voltage gain requirements R_2 / (R_1 + R_2)> 1/3.