Hey guys,
I have a few questions. In this schematics of a mosfet h-bridge, http://www.cadvision.com/blanchas/hexfet/np-s.htm
he has a 47k resistor connected to the base of the npn bipolar transistor, and 33k to the pnp bipolar. Why is it designed like that? Can't both values be the same? What differences does it make?
Also, I've read about using opto-couplers to connect a h bridge to a microcontroller to eliminate noise from the motors. I have a nand logic circuit that takes two inputs, enable and direction, and outputs it into the A, B, C, D terminals in that h bridge. Should i put the opto-couplers between the h bridge and the nand circuit, or the microcontroller and the nand circuit?
Thirdly, I want to do PWM for the h bridge. would it be better to keep one mosfet on the whole time it's going in one direction, while switching the other, or swtich both mosfets at the same time, on and off. Does it make a difference? If so, should i send the pwm signal to the N channel or P channel?
Thank you guys so much!
I have a few questions. In this schematics of a mosfet h-bridge, http://www.cadvision.com/blanchas/hexfet/np-s.htm
he has a 47k resistor connected to the base of the npn bipolar transistor, and 33k to the pnp bipolar. Why is it designed like that? Can't both values be the same? What differences does it make?
Also, I've read about using opto-couplers to connect a h bridge to a microcontroller to eliminate noise from the motors. I have a nand logic circuit that takes two inputs, enable and direction, and outputs it into the A, B, C, D terminals in that h bridge. Should i put the opto-couplers between the h bridge and the nand circuit, or the microcontroller and the nand circuit?
Thirdly, I want to do PWM for the h bridge. would it be better to keep one mosfet on the whole time it's going in one direction, while switching the other, or swtich both mosfets at the same time, on and off. Does it make a difference? If so, should i send the pwm signal to the N channel or P channel?
Thank you guys so much!