Hi all,
The following circuit is meant for driving a stepper motor. Now I have a unipolar stepper motor( 6 leads) with 5 v and 1.6 amps rating. What are the modifications I need to do so that this circuit can drive the motor. I know I need to use 5 v inplace of 12 v for supply to the motor. Do I need to use some other transistors ( more powerful)? The parts list is as follows
R1, R2 ,R3, R4 4 1K 1/4W Resistor
D1, D2, D3, D4 4 1N4002 Silicon Diode
Q1, Q2, Q3, Q4 4 TIP31 NPN Transistor (See Notes) TIP41, 2N3055
U1 1 4070 CMOS XOR Integrated Circuit
U2 1 4027 CMOS Flip-Flop
S1 1 SPDT Switch
I am new to this field. So any help in this regard is highly appreciated.
Samik

 

The 1N400x series diodes are very slow to recover, and will hurt performance.
Consider a fast recovery diode rated for 2A or more, something like a PS200R, PS201R, PS202R etc.

The TIPxx and 2N3055 will require far more base current than the 4027 flip-flop can provide. Consider using N-ch power MOSFETs instead, like IRLD024's. If you are using less than a 10v supply for your logic, you will need to use logic-level N-ch power MOSFETS; the IRLD024 is logic level. You will need to provide large traces on the board for heat sinking with that MOSFET.

As an alternative, consider IRLU8721 MOSFETs. These are pretty cheap, can sink up to 30A, and have a low gate charge. They are also smaller than TO-220 packaged devices, as they are in an I-Pak package. You probably will not need to provide heat sinking for these MOSFETs in your application.

The gate terminals get connected to the outputs of the 4027 via the resistors (use ~200 Ohm resistors instead of 1k).
The source terminals get connected to ground.
The drain terminals sink current from the stepper motor wires.

 

Thanks for your reply.

 

Hi SgtWookie,
The following schematic shows how the motor needs to be connected to the transistor circuit. Given this diagram, I think the +12 V supply to the motor ( which goes to the negative terminal of the diodes) in the previous figure (stepper.gif) needs to be changed to ground.
Kindly give your suggestion. I have ordered the MOSFET's.Hopefully the circuit will work as you told
Thanks
Samik