Generating pulses for Stepper Motor without Microcontroller

Thread Starter

ErjonAmeti

Joined Apr 22, 2019
7
Hello
I want to generate 4 pulses with a different time to control a stepper motor but only in Analog way. To simulate the stepper motor, I'm planning to use some Leds. I was thinking to combine to Astable Multivibrator but I don't know if this can work. What do you suggest besides using a microcontroller or a 555 timer ?
 

AlbertHall

Joined Jun 4, 2014
8,330
Four monostables connected in a ring so each one triggers the next.
Do monostables count as analogue?
 

Thread Starter

ErjonAmeti

Joined Apr 22, 2019
7
1572970395584.png
If is it possible to control the frequency with some kind of RLC Circuit, would be great. For example calculating the capacitor value or resistors value to generate a pulse.
 

BobTPH

Joined Jun 5, 2013
2,021
Why are you using a stepper? If you are going to just keep sending step sequences at a constant rate, an ordinary motor would do. Steppers are good when you need to control the position by counting the steps.

Bob
 

MaxHeadRoom

Joined Jul 18, 2013
19,012
A stepper motor controller also controls rotation rate, which an ordinary open loop motor cannot guarantee.
As per post #2, is this a bi-polar or uni-polar type?
The input to the typical drive is just a step signal and either a constant 0 or 1 for the direction.
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
19,012
There are also many App notes out there from ST and Allegro etc, e.g. StepperST.PDF.
Max.
 

crutschow

Joined Mar 14, 2008
23,314
Below is the LTspice simulation of a circuit to generate your 4-phase sequence.
It uses a 555 timer to generate the clock and a CD4017 Johnson decade counter for the sequence.
The 555 timer generates a clock frequency range of about 75Hz to 1300Hz by adjustment of pot U3.
This range can be changed by using a different value for the U3 pot and/or capacitor C2.
Larger values reduce and smaller values increase the frequency range.
Of course you need to add driver stages on the output to power the motor.

1572979822707.png
 
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Thread Starter

ErjonAmeti

Joined Apr 22, 2019
7
Why are you using a stepper? If you are going to just keep sending step sequences at a constant rate, an ordinary motor would do. Steppers are good when you need to control the position by counting the steps.

Bob
I know, I just want to make this electronic control... for fun :p
 

Thread Starter

ErjonAmeti

Joined Apr 22, 2019
7
Below is the LTspice simulation of a circuit to generate your 4-phase sequence.
It uses a 555 timer to generate the clock and a CD4017 Johnson decade counter for the sequence.
The 555 timer generates a clock frequency range of about 75Hz to 1300Hz by adjustment of pot U3.
This range can be changed by using a different value for the U3 pot and/or capacitor C2.
Larger values reduce and smaller values increase the frequency range.
Of course you need to add driver stages on the output to power the motor.

View attachment 190661
Thanks
Im going to try also this with 555 timer.
 

Thread Starter

ErjonAmeti

Joined Apr 22, 2019
7
A stepper motor controller also controls rotation rate, which an ordinary open loop motor cannot guarantee.
As per post #2, is this a bi-polar or uni-polar type?
The input to the typical drive is just a step signal and either a constant 0 or 1 for the direction.
Max.
I just want a constant rate of speed.
Bi-polar type.
 

MaxHeadRoom

Joined Jul 18, 2013
19,012
I just want a constant rate of speed.
Bi-polar type.
If the constant rate is relatively high you require a means of maintaining the motor plate current as the motor inductive reactance increases, this once was done using a simple resistance to control constant current
Now it is common to use a higher than rated voltage for the drive and maintain the rated current by electronic means.
In your case, if using a constant RPM, then you could adjust the supply a fixed voltage accordingly.
Max.
 

shortbus

Joined Sep 30, 2009
6,976
It seems strange to me that some people think steppers weren't viable until the advent of micro controllers.
 

MrChips

Joined Oct 2, 2009
19,270
You can create the drive signals for a 5-lead bipolar stepper using a simple 2-bit Gray Code counter.
The counter cycles through four states: 00, 01, 11, 10 ...
Two windings are fed the signals from the two bits. The other two windings are the complement of the first two signals.
 

MrAl

Joined Jun 17, 2014
6,469
Hello
I want to generate 4 pulses with a different time to control a stepper motor but only in Analog way. To simulate the stepper motor, I'm planning to use some Leds. I was thinking to combine to Astable Multivibrator but I don't know if this can work. What do you suggest besides using a microcontroller or a 555 timer ?
Hi,

Look up "walking ring counter". That is probably the simplest.

You can also use a regular 2 bit counter with a 1 of 4 decoder.

For any of these you need a clock signal also which can be a 555 or just two logic gates set up as an oscillator which then also gives you the option of using a crystal for superb stability.
 
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