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Simple way(s) to run a bipolar stepper motor?

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sorveltaja:
This should rather be "how not to use this or that to achieve this or that".

Anyways, I have few bipolar stepper motors, one from old printer and another from HP scanner and also Nema 17 ones, which I used to test as hand-cranked generators.

I think I'll stick with Nema 17, as it's easier to find specs for them.

Specs that are in the motor itself:

Made by Joy-It
Model Nema 17-04
Holding torque 0,5 Nm
Phase resistance 2.20 Ohms
Rated voltage 3.3V
Rated current 1.5A
Step angle 1.8 deg

As I don't have Arduino or any other such devices, I started to look for simpler ways to run a stepper motor. I mean, how were those buggers controlled before Arduinos and such software controlled hardware?

So far, as a starting point, I've managed to find rather simple schematic, which uses 4017(decade counter) and audio amplifiers(TDA2030): https://electronicscheme.net/stepper-motor-controller-using-tda2030/

As I don't have 2030's in my shelf, I decided to use what I have, as a leftover from past project - LM386's.

Anyways, that gave me an idea to test a schematic of 4017-386 based circuits to get a working sequence to run the this bipolar stepper - it's been (again) like a guessing game - like building something out of Lego blocks - whatever produces desired result, is a keeper.

It was positive surprise to see, that by using those wimpy audio amps, it is possible to drive this bipolar stepper(Nema 17-04) with 400mA at 5-6 volts without burning out involved components.

So far, this is the simplest circuit after some testing. 4017 uses function generator for supply and signal, and 386 uses bench psu (For clarity, I have omitted supply connections and spike-reducing diodes):



Signal rate/frequency, where the torque is most notable is from about 1-150 hz(or probably half of that, as that 4017 acts like a flip-flop), though. Above that the motor just jitters.

But that might well be more than enough for the purpose I have in mind, as it doesn't require as much torque/speed as that circuit provides.

But there is this serious issue of vibration when using full-steps (I guess this circuit  uses such).

Obvious solution - why not use microstepping? That's where I am at this point - trying to figure out how to approach it from an uneducated position.

Another (and perhaps a lot easier) possibility could be to just use something to absorb/dampen the vibrations.

efrench:
So do you just want to run the stepper as a dc motor or do you want to do indexing as well?

Arduinos, stepper drivers, and lcds can be had on AliExpress for less than $5 each. 

sorveltaja:
I'm just looking for running the stepper at a certain, stable speed. That's pretty much what I have already achieved.

I had two A4988-based drivers, but it's way too easy to fry them by accident.

What I'm also trying to find out, if I can make something, that produces a half-step sequence using only discrete, analog components. If I manage to do that, it's fine. If I don't, that's also fine. Be it either way, next step is to see what plan B has to offer.

I just like to test things and find out what I don't know, and perhaps learn thing or two, while at it.

From previous projects I learned how to make stepped voltage waveforms/sequences.

But here we have current, and difference between the two phases involved:


 
If memory serves, I haven't had projects before, which use that much(400-500mA) current.

I already tested one voltage-to-current converter schematic on a breadboard, and yeah, included transistor and resistor got really hot. Now I know at least one thing, of what not to do to melt a breadbord.

efrench:
I have a stepper driver from 2002 which doesn't need a microprocessor.  It's Kit #109 from kitsrus.com.

BillTodd:
Just make a sine oscillator and add a 90 degree phase shifter for the second phase. The motor doesn't have to step.

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