Controlling a motor using a 12V line , and using arduino to vary resistance

Using Arduino Project Guidance
1

I recently finished a project to control a DC motor with the L298N module with arduino, however one of the main problems i have encountered is that when using a low duty cycle (when the pulses are short) it does a high pitched whine noise till i get it to about 25% duty cycle then itl will jerk slightly and start spinning slowly. I Want to completely eliminate this problem by instead providing full 12V to the Motors, and instead make the arduino control a resistor to the motors so that way it can operate smoothly from 0-12V, aka no pulses. Just pure 12V DC, 9V DC, 8V DC, etc. I believe i need to use a relay but any sort of guidance on what parts to get would be greatly appreciated. Thank you

2

These are very old and inefficient drivers.

Try a proper MOSFET driver from Pololu.

3

No, no, no. That's crazy.
Please post links to the datasheets for the motor and the power supply.
The symptoms You tell about are surely due to a kind of mismatched devices.
A pen and paper schematics could be valuable for solving the issue.

1 Like
4

I see your name is railroader! im actually trying reactivate an old busted O scale train, when i used the L298N it had alot of whine before starting to move, but im trying to get it to move slowly with out the whine noise.
The motor in question: https://datasheetspdf.com/pdf/1236558/MABUCHI/RS-385SH/1
L298N module: https://components101.com/sites/default/files/component_datasheet/L298N-Motor-Driver-Datasheet.pdf

Ive asked this question also on other hobby shops and they pinpoint the L298N module as the main culprit

5

any guides out there on how to intergrate it with arduino?
these look like they can get the job Done Pololu - Mini MOSFET Slide Switch with Reverse Voltage Protection, LV

6

Let’s make some assumptions.

Say your Arduino UNO gets the engine to start moving (without whining) when you do analogWrite(motorPin, 48);

The solution then is to never use less than 48. :thinking:

You can also experiment using the timer one library to generate a higher PWM frequency.


#include <TimerOne.h>

#define pwmRegister OCR1A const int outPin = 9;

long period = 10000; long pulseWidth = 1000;

// the logical pin, can be set to OCR1B // the physical pin

// the period in microseconds // width of a pulse in microseconds

int prescale[] = {0,1,8,64,256,1024}; // the range of prescale values

void setup() { Serial.begin(9600); pinMode(outPin, OUTPUT); Timer1.initialize(period); setPulseWidth(pulseWidth); }

void loop() { }

// initialize timer1, 1000 microseconds

bool setPulseWidth(long microseconds) { bool ret = false;

int prescaleValue = prescale[Timer1.clockSelectBits];

// calculate time per counter tick in nanoseconds long precision = (F_CPU / 128000) * prescaleValue ; period = precision * ICR1 / 1000; // period in microseconds if( microseconds < period) {

int duty = map(microseconds, 0,period, 0,1024); if( duty < 1)

duty = 1;

if(microseconds > 0 && duty < RESOLUTION) {

Timer1.pwm(outPin, duty);

ret = true; }

} return ret;

}

But get a better motor driver too.

7

The L298 is stone age technology wasting 2 - 4 volts due to the Darlington transistors. Go for MOSFET based H-bridges.
Polulu (?) is said to sell such ones.

Make sure the bearings are lubricated? If they are dry they will produce a screaming noise.

Trust @ LarryD

8

Try this to see at what PWM DC the motor starts to move.

You need to install the TimerOne.h library.

This line set the PWM frequency:

  Timer1.initialize(100);  //100us = 10khz

Pin 9 goes to ENA
Set your IN1 and IN2 pin levels to set the direction.

//Arduino UNO

#include <TimerOne.h>

void setup()
{
  Serial.begin(9600);
  
  pinMode(9, OUTPUT); //Use pin 9 or 10
  Timer1.initialize(100);  //100us = 10khz
  Timer1.pwm(9, 750);      // 50% DC
  // You can use 2 to 1023
  // 0 & 1 gives a constant LOW
  // 2     gives ~125ns HIGH pulses
  // 512   gives 50us (50%)
  // 1023  gives ~125ns low pulses
  // 1024  gives a constant HIGH
}

void loop()
{
  for (int x = 200; x <= 1024; x++)
  {
    Timer1.pwm(9, x);
    delay(100);
    Serial.println(x);
  }

}
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