Notify me of new posts via email. Yeah, this is just a prototype and I was worried about one transistor “hogging” the current. Hello Phil, did you connect the motor between ground and emitter? As you can see from the waveform of the winding current, the rise time has been dramatically improved. If your load is highly inductive, like motors, care should be used in diodes choice: It’s not like if I move forward 10 steps, back 1, forward 10, etc. Now you want to put current through a coil.

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This one seems to work ok as-is. Using a higher voltage makes the current rising faster. It really needs a proper stepper motor driver that has current limiting and can drive it with a high voltage 24v, maybe 50v supply.

Necessity is the mother of invention. The transistor may burnt. Drive the gate of the mosfets with a small ohm resistor. You will need to go with a microcontroller or with a stepper driver. Hence the drive voltage is “chopped”.


The IRLN can take 36 amps. Does the circuit can run these motors? Great, that is good to know.

MOSFETs for stepper motor control | Electronics Forum (Circuits, Projects and Microcontrollers)

Please help me out. Then you can find the current in the datasheet? At 6 March If you haven’t any high speed diode, best to use slow 1N then none.

I have plenty of torque, and in fact, the thing pinched my thumb from all the torque! As for your stepper motor, it can be used in either bipolar or unipolar mode.

BI-Direction Motor Speed Control Circuit LM324 Mosfet IRF9540 IRF540

Spin the motor shaft at rpm and note the rms voltage from the winding. You are commenting using your Twitter account. Two or three hours spent thinking and reading documentation solves most programming problems. It’s like putting your foot hard on the accelerator in a car, and controlling the speed by how hard you press the brake. Yeah, this is just a prototype and I was worried about one transistor “hogging” the current.

Stepper Motor Driver Problem — Parallax Forums

But to be sure i had a question. This is not the only way to do that, but is the most common.


At 2 January The IRF is a better choice: Much better to use a cheap Darlington transistor then. See the reference below: Bill Of Materials Semiconductors. Now you want to put current through a coil. I’ll be using the PWM hardware from a pic though, so that has adjustable deadband stuff built in.

Thank you very much!!!! I also doubled up on the transistors and just lopped two together in parallel for every one in the schematic. But as StefanL38 said in ird540 thread,”Do you have an oscilloscope Wiring as demonstrated in D: Hi vish, to overcome this problem you should use a linear speed profile, where the step rate should be incremented linearly using constant acceleration.