74—1型离心机一次可制备较多的化验标本,但该机的可控硅很容易损坏。针对这个问题,我们对原机作了某些改进,取得较好效果。可控硅损坏原因从图1可见,在市电电压的一个周期中,两只可控硅在触发电压作用下轮流导通。触发电压取自阻容移相桥电路。改变W_1电位器的阻值即可改变移相角的大小,从而改变加在电机上的电压,使电机变速。 74-1 centrifuge can be prepared more laboratory specimens, but the machine SCR can easily be damaged. In response to this issue, we made some improvements to the original machine, and achieved good results. SCR damage causes Can be seen from Figure 1, in a period of mains voltage, the two thyristors turn on the role of trigger voltage turns. The trigger voltage is taken from the resistor-capacitor phase-shift bridge circuit. Change the resistance of the W_1 potentiometer to change the phase shift angle, thus changing the voltage applied to the motor, the motor speed.