I adopted the following link's circuit to build 4 set drivers. Two sets run fine. The other two have much noise, or the steps loss. One of them has malfunctioning in microstepping. Since the circuits are all identical and were checked thoroughly. I think the circuit doesn't have problem. Instead, I am now wondering if there are some down grade ICs were mixed in batch that I purchased. Does anyone has such experience?
Dual Chopper Stepper Driver