ir2101 application
Hi max_imum2000,
You are right the TIP120, 122 etc.. does have body diodes in them. But the recovery time for these diodes may be too slow for this type of application so you might want to put some faster diodes around them for protection against reverse voltage flyback. Now as for the resistor pair I started to think that they were using them to help prevent an overlap of conduction for q1 & q2 or q3 & q4 but this would also work against you on turn off as well as turn on so I am not sure. I have recently been doing some stepper motor drive using hbridges and have been controlling them with a basic stamp. I have been using the IR2101 high side and low side drivers with good success. I am also using simple IRF530 fets in place of the transistors ... also with success. No resistors on the gates just straight drive .. Works for me.....
Good luck
dfullmer