[delta67]

Hi all,
I've a stepper motor and I want to power it with 35V @ 1A.
Is it possible to control the motor's current without using a special chopper IC like SLA7024M?
If we control (with a fast microcontroller) the time the winding is energized perhaps we can limit the current, No?
Thanks

[grg12]

Yes. That's exactly what chopper chip does. Just make sure you have a fuse - should the microcontroller crash due to program error (or the electronic is designed in a way that guarantee coil won't be energized forever)

Wysłane z mojego GT-N7100 przy użyciu Tapatalka

[delta67]

Thanks grg12 for the quick reply!!
Have you, please, any ideas to optimise code?
How to calculate the necessary time to energize the coil to reach the wanted current?
Is there a solution to build a chopper with op-amp + logical gates ? What you think about the attached circuit?

[grg12]

What you think about the attached circuit?

Attached schematic schows basic idea how chopper circuit work - not a practical device. The only reason to build it will be school exercise - and even then it will require many additional components.

Is there a solution to build a chopper with op-amp + logical gates

um... yes, but WHY?

Have you, please, any ideas to optimise code

No

[delta67]

um... yes, but WHY?

In fact, I'm from a country (3rd world) where it's difficult to find such a special control ICs !!
Once I salvaged an SLA7024M and a unipolar stepper from an old printer.
Can we use the UC3843 (SMPS controller)? It has a PWM and current limiting functionality.

[grg12]

In fact, I'm from a country (3rd world) where it's difficult to find such a special control ICs !!

Ok, that explains a lot

Can we use the UC3843 (SMPS controller)? It has a PWM and current limiting functionality.

I looked dataschet of this chip - i think you can use it to drive unipolar motor. But it won't be easy

[delta67]

OK, I think the project Mardus-kreutz is very interesting since kreutz has developed a chopper without special IC.