当电源的滤波电阻坏了,一时又找不到大功率的电阻,或临时需要大功率的可变电阻,那么用一支强放管来代替是最方便的,其电路可按图1来接. 调整电位器R,就改变了电子管的栅压,于是电子管的内阻也随之改变.图示的电路,电子管用6V6或6L6时,调节R,内阻可从3千欧到6千欧间变化;若采用其它型号的电子管,或用几只管并联使用,阻值还 When the power of the filter resistance is broken, sometimes can not find high-power resistance, or temporarily need high-power variable resistance, then use a strong tube to replace the most convenient, the circuit can be connected according to Figure 1 Adjusting the potentiometer R changes the gate voltage of the tube, so the internal resistance of the tube also changes.If the circuit shown in the figure, when the tube with 6V6 or 6L6, adjust R, the internal resistance can be from 3 kΩ to 6 kΩ Between changes; If other types of tubes, or use a few tubes in parallel, resistance also