Hi, To enlarge the 3.6 V of PWM wave of MCU to 6 V which control on and off of transistors. But op-amp part never amplifies out . Simulation diagram is shown in the figure. Op-amp is LM368h and 8 v single power supply.The datasheet of LM368h is http://www.kynix.com/Detail/458662/LM368H-2.5.html. During the simulation time, I will adjust R1 of potentiometer to 666 ohm indeed which can amplify voltage to 6V. But in the actual circuit, even if R1 is set to 1 k, it can only be adjusted to about 4.25 V. If I amplify the power supply of op-amp, for example to the 12 v or so, it is 6 v. I thought for a long time, but I don't know what's the problem.Generally op-amp can be amplified to VCC - 0.8 V, which is about 7 V. But actually it cannot meet. Thank you very much!