Servo Motor&Op Amp&MOSFET circuit

Thread Starter

rmirayk

Joined Sep 3, 2019
3
I made a circuit and my aim was creating an Op Amp circuit with changeable voltage(MOSFET) for driving 12V & 24V servo motors. But I know my circuit is not good. I should use voltage divider and I should be able to change voltage to 24V from 12V with a switch and MOSFET. Can you please help me?
 

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dendad

Joined Feb 20, 2016
2,989
You need to be a bit more specific.
"Servo" is a fairly wide definition.
Can you post a picture of your servo?
If you are referring to the type of servo used in RC models, you need to produce a pulse train PWM signal that varies between fixed limits.
https://learn.sparkfun.com/tutorials/hobby-servo-tutorial/all
Or, if you are talking about a servo motor driven by a PWM signal, the PWN can go from 0 to 100%.
https://en.wikipedia.org/wiki/Servomotor
Either way, your circuit is not really suitable.
Have you read up on servos and servo motor systems?
 

Thread Starter

rmirayk

Joined Sep 3, 2019
3
You need to be a bit more specific.
"Servo" is a fairly wide definition.
Can you post a picture of your servo?
If you are referring to the type of servo used in RC models, you need to produce a pulse train PWM signal that varies between fixed limits.
https://learn.sparkfun.com/tutorials/hobby-servo-tutorial/all
Or, if you are talking about a servo motor driven by a PWM signal, the PWN can go from 0 to 100%.
https://en.wikipedia.org/wiki/Servomotor
Either way, your circuit is not really suitable.
Have you read up on servos and servo motor systems?
https://www.servocity.com/servos/futaba-servos I want to use a commercial servo unit like one of these. I know that my circuit is set up as a linear regulator. The circuit should generate a pulse train. But I don't know how to provide these requirements.
 

dendad

Joined Feb 20, 2016
2,989
The easiest way to do your job is to use an Arduino.
There are plenty of examples around.
A linear reg will not work.
Also, the PWM must be in a specific range,
This is a pretty good intro I think, after just a quick browse through...
Code:
/*
Controlling a servo position using a potentiometer (variable resistor)
by Michal Rinott <http://people.interaction-ivrea.it/m.rinott>

modified on 8 Nov 2013
by Scott Fitzgerald
http://www.arduino.cc/en/Tutorial/Knob
*/

#include <Servo.h>

Servo myservo;  // create servo object to control a servo

int potpin = 0;  // analog pin used to connect the potentiometer
int val;  // variable to read the value from the analog pin

void setup() {
  myservo.attach(9);  // attaches the servo on pin 9 to the servo object
}

void loop() {
  val = analogRead(potpin);  // reads the value of the potentiometer (value between 0 and 1023)
  val = map(val, 0, 1023, 0, 180);  // scale it to use it with the servo (value between 0 and 180)
  myservo.write(val);  // sets the servo position according to the scaled value
  delay(15);  // waits for the servo to get there
}
as an example.
 

MaxHeadRoom

Joined Jul 18, 2013
19,014
You show an output to a 'servo' is this a drive for a commercial servo?
You can obtain commercial servo drivers that accept either ±10vdc (analogue) or step/dir type command signal.
If not RC type, more info is required and what you are trying to achieve?
A servo, other than RC infers a closed loop that includes PID feedback.
The other alternative is open loop control.
The other open loop servo that requires no feedback loop is a stepper motor.
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
19,014
https://www.servocity.com/servos/futaba-servos I want to use a commercial servo unit like one of these. I know that my circuit is set up as a linear regulator. The circuit should generate a pulse train. But I don't know how to provide these requirements.
There are many examples of controllers for RC servo's out there from 555 IC's to Picmicro, complete with program.
The requirements for RC is not run of the mill PWM.
Op amp won't cut it.
Max.
 
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