Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: mohamed on February 02, 2008, 05:12:15 AM

Title: can i use stepper instead of servo?
Post by: mohamed on February 02, 2008, 05:12:15 AM
can i use stepper instead of servo coz i already have a stepper?
Title: Re: can i use stepper instead of servo?
Post by: benji on February 02, 2008, 06:48:30 AM
check your torque requirements, steppers with the same torque are much much more expensive
Title: Re: can i use stepper instead of servo?
Post by: SmAsH on February 02, 2008, 06:53:46 AM
but arent servos usially cheaper than steppers? or can you get them for cheap?
Title: Re: can i use stepper instead of servo?
Post by: mohamed on February 02, 2008, 07:06:35 AM
i have this problem that i cant ind servo in my country and i didnt also find this ESC motor thing
i only have a normal dc motor with two wires so anyone can tell me how to connect it to the 50$ robot i'll be thankfull to him
Title: Re: can i use stepper instead of servo?
Post by: SmAsH on February 02, 2008, 07:08:10 AM
what country are you in?
Title: Re: can i use stepper instead of servo?
Post by: Rebelgium on February 02, 2008, 07:45:18 AM
i have this problem that i cant ind servo in my country and i didnt also find this ESC motor thing
i only have a normal dc motor with two wires so anyone can tell me how to connect it to the 50$ robot i'll be thankfull to him

So what do you want to do now? use a stepper motor (4 or more wires) , or use a DC motor (two wires)?
anyway, to use a DC motor you'll need a motor driver, to use a stepper motor you'll need a stepper controller.
Do some research.

using a modified servo is much easyer, but if you really cant find it, then use a DC motor or a stepper
Title: Re: can i use stepper instead of servo?
Post by: ed1380 on February 02, 2008, 09:41:35 AM
a stepper motor is harder to use than a regular dc motor.

check admins tutorial on h-bridges. I'm sure you can get 8 transistors or mosfets. and then make it yourself
Title: Re: can i use stepper instead of servo?
Post by: benji on February 02, 2008, 12:03:42 PM
if you need the capabilities of a servo its really hard to make it out of a dc motor yourself,its a total project cuz you have to do a decent driver.
using a stepper with big torque would cost yo a lot,,so try to buy the servos from a different country and have em shipped to you
Title: Re: can i use stepper instead of servo?
Post by: mohamed on February 02, 2008, 12:18:55 PM
i heard that the atmega32 has a built in motor driver so i think this will solve the problem for me as i can have a dc motor and put it on the atmega32 so if there is any problem with that plz let me know
but i dont know if i have to change the programming code or not
Title: Re: can i use stepper instead of servo?
Post by: ed1380 on February 02, 2008, 12:21:01 PM
dc motor will suck too much current and fry the atmega
Title: Re: can i use stepper instead of servo?
Post by: paulstreats on February 02, 2008, 12:37:47 PM
Quote
i heard that the atmega32 has a built in motor driver

I think you heard wrong.

What is probably meant is "the atmega 32 has built in pwm for use with a motor driver"
Title: Re: can i use stepper instead of servo?
Post by: SmAsH on February 02, 2008, 04:44:06 PM
Quote
i heard that the atmega32 has a built in motor driver

I think you heard wrong.

What is probably meant is "the atmega 32 has built in pwm for use with a motor driver"
yes you are correct.
Title: Re: can i use stepper instead of servo?
Post by: mohamed on February 02, 2008, 04:58:23 PM
now i think thati dont have a solution except that i have to get the servo right?
Title: Re: can i use stepper instead of servo?
Post by: benji on February 02, 2008, 05:09:54 PM
right
Title: Re: can i use stepper instead of servo?
Post by: ed1380 on February 02, 2008, 06:33:21 PM
or an ESC and dc gearmotor
Title: Re: can i use stepper instead of servo?
Post by: SmAsH on February 02, 2008, 06:58:28 PM
well you can get servos for pretty cheap now. me? i use dc motors. lol ;)
Title: Re: can i use stepper instead of servo?
Post by: benji on February 03, 2008, 05:19:04 AM
Quote
well you can get servos for pretty cheap now. me? i use dc motors. lol

did you make your own driver?(capable of imitating the hobby servos capabilities?)
Title: Re: can i use stepper instead of servo?
Post by: Rebelgium on February 03, 2008, 07:03:42 AM
no smash just much he uses dc motors for continuous rotation. He doesn't use them as servo's.
Title: Re: can i use stepper instead of servo?
Post by: mohamed on February 03, 2008, 02:13:45 PM
ok smash do u know how to use the dc motor with the 50$ robot i mean can u really coonect it to the microcontroller like the servo? ???
Title: Re: can i use stepper instead of servo?
Post by: SmAsH on February 03, 2008, 02:18:31 PM
i havent built the $40 robot and if i did i probibly would use servos
Title: Re: can i use stepper instead of servo?
Post by: Rebelgium on February 03, 2008, 02:55:21 PM
mohamed read some tutorials and read the replies better. you can find this info everywhere on SoR.

To use DC motors you'll need a motor driver. You can't connect them directly to a microcontroller.
Title: Re: can i use stepper instead of servo?
Post by: mohamed on February 03, 2008, 09:19:03 PM
i do read the replies well but all i ment that if anyone did use the dc motor with the 50$ robot coz it will be i think and im not sure another programming code for the microcontroller that all im asking
Title: Re: can i use stepper instead of servo?
Post by: benji on February 04, 2008, 11:12:48 AM
you can never use a dc motor instead of servo if you want to use it as a servo unless you build the driver which is kind of impossible for a non-electronics engineer to do(its a big project itself)
in case you only want to turn the motor (left or right) you can hook up a dc motor driver ic with the micro and the dc motor
Title: Re: can i use stepper instead of servo?
Post by: mohamed on February 04, 2008, 11:17:54 AM
thank u benji for ur help as i already get the L293D motor driver ic but i dont know how to connect it to the micro so if u can help i'll be greatfull to u  ;D
Title: Re: can i use stepper instead of servo?
Post by: Rebelgium on February 04, 2008, 11:42:27 AM
just search google.
http://www.8051projects.net/_L293D_schematic
http://www.me.umn.edu/courses/me2011/robot/technotes/L293/L293.html
Title: Re: can i use stepper instead of servo?
Post by: benji on February 04, 2008, 04:37:06 PM
its all in the datasheet