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贵刊1996年第1期刊出的《给3V收音机加装触摸开关》一文,经笔者试验电路完全可进行正常工作,但美中不足的是:电池耗电量较大。因为收音机打开时,V2向V3 提供的基极电流约5mA(假设V2的β=100, V2的基极电流为3V-3个二极管正向压降/ 20kΩ=0.05mA,所以V2的集电极电流为 100×0.05=5mA),这一种的损耗太大,实际上这一路电流降至0.5mA甚至更小电路仍能稳定工作。所以笔者为减小这一电流给 V2加一集电极电阻Rc=3.2kΩ,从而有效地防止了电能的不必要的消耗。
Your first issue in 1996 published “to 3V radio touch switch installed” article by the author test circuit can be normal work, but the fly in the ointment is: a larger battery power consumption. Since the base current V2 provides to V3 is about 5mA when the radio is on (assuming V2 of V2 = 100 and V2’s base current is 3V-3 diodes forward voltage drop / 20kΩ = 0.05mA, the V2 collector current 100 × 0.05 = 5mA), this type of loss is too large, in fact, the current down to 0.5mA or less circuit is still stable. So I reduce the current to V2 plus a collector resistance Rc = 3.2kΩ, thus effectively preventing unnecessary consumption of electricity.