how to build a drawing machine

[Rksk]

Neo,

I was reading this topic at the start because It is very interesting to me too.

I have some things to say,

1. this project wants some mechanical suffs, so Sheal have to find them from his area.

2. as I think, this will draw a picture wich we select from computer. so the resolution is a problem. if we going to draw high resolution things, it will get much time to complete.

3. I saw Neo have said that, CD-ROMs have stepper motors. But i have never seen any?

4. if Shenal haven't programing knowladge, he has to start learning it soon.

5. shenal has only one month for this project.

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[Rksk]

Also,

I think you all have read the topic Donation of PIC KIT to RkskEkanayaka 26-04-2010.

So, we all have to say "Thank You Very Much" to our great brother/teacher/friend Neo.

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[Rksk]

I found some pics on the topic. they are different,

drawing machine01.jpg (13.69 KiB) Viewed 20350 times

Drawing machine02.jpg (52.47 KiB) Viewed 20350 times

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drawing machine04.jpg (24.56 KiB) Viewed 20350 times

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[Neo]

3. I saw Neo have said that, CD-ROMs have stepper motors. But i have never seen any?

I did say For this, it is easier to use the stepper motor used in CD-ROM tray. The main motor is a BLDC (Brushless DC motor). I was referring the motor which is on a side to open/close disk tray. This is a stepper motor.

I agree with you on all other points. However, when there is a will, there is a way

[Rksk]

3. I saw Neo have said that, CD-ROMs have stepper motors. But i have never seen any?

I did say For this, it is easier to use the stepper motor used in CD-ROM tray. The main motor is a BLDC (Brushless DC motor). I was referring the motor which is on a side to open/close disk tray. This is a stepper motor.

No, it's a normal DC motor. But the motor wich rotates the CD is a stepper motor. Also we can find stepper motors from DC Fans wich used in computers & ect.

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[Neo]

We have discussed about this in How to connect CD-ROM motor to PIC microcontroller?. I guess you missed it?

Anyway, the main motor is a BLDC servo motor for sure. See the wiki article http://en.wikipedia.org/wiki/Brushless_ ... tric_motor. Read Applications -> Consumer electronics and notice the following.

BLDC motors have come to dominate many applications particularly devices such as computer hard drives and CD/DVD players. Small cooling fans in electronic equipment are powered exclusively by BLDC motors.

BLDC.jpg (14 KiB) Viewed 20341 times

The motors with a feedback mechanism is called Servo motors. Usually you can read RPM in real-time (With sensors like hole-effect sensors) which make it possible to control RPM by varying power.

Stepper motor is also a brushless motor but its mechanism is different. Stepper motors effectively have multiple "toothed" electromagnets arranged around a central gear-shaped piece of iron. The electromagnets are energized by an external control circuit, such as a microcontroller. To make the motor shaft turn, first, one electromagnet is given power, which makes the gear's teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are aligned to the first electromagnet, they are slightly offset from the next electromagnet. So when the next electromagnet is turned on and the first is turned off, the gear rotates slightly to align with the next one, and from there the process is repeated. Each of those slight rotations is called a "step", with an integer number of steps making a full rotation. In that way, the motor can be turned by a precise angle.

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All these are taught in full detail for mechanical engineering. I'll ask Magneto to write up something to confirm. He is a mechanical & electronics engineer

[PraveenAlexis]

Neo,

I was reading this topic at the start because It is very interesting to me too.

I have some things to say,

1. this project wants some mechanical suffs, so Sheal have to find them from his area.

2. as I think, this will draw a picture wich we select from computer. so the resolution is a problem. if we going to draw high resolution things, it will get much time to complete.

3. I saw Neo have said that, CD-ROMs have stepper motors. But i have never seen any?

4. if Shenal haven't programing knowladge, he has to start learning it soon.

5. shenal has only one month for this project.

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shenal has a knowledge of programming since hes learning turo pascal, we thought of doing the project with turbo pascal earlier but it wasnt a good idea
ALSO I FOUND THIS ON WIKI

Brushless DC motors (BLDC motors, BL motors) also known as electronically commutated motors (ECMs, ROBOT.LK motors) are electric motors powered by direct-current (DC) electricity and having electronic commutation systems, rather than mechanical commutators and brushes. The current-to-torque and frequency-to-speed relationships of BLDC motors are linear.
BLDC motors may be described as stepper motors, with fixed permanent magnets and possibly more poles on the rotor than the stator, or reluctance motors. The latter may be without permanent magnets, just poles that are induced on the rotor then pulled into alignment by timed stator windings. However, the term stepper motor tends to be used for motors that are designed specifically to be operated in a mode where they are frequently stopped with the rotor in a defined angular position; this page describes more general BLDC motor principles, though there is overlap.

[Rksk]

http://www.rcgroups.com/forums/showthread.php?t=292737

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[PraveenAlexis]

NEW TOPIC
i have a hard disk motor and i need to run it on 7200rpm speed it has 4 connectors,
i need to know "how to connect those ports to the power supply

EDIT:// like this in this link
[media]http://www.youtube.com/watch?v=LabMAEde ... e=youtu.be[/media]
do i have to design a circuit??
i found this on a site

I used this code for my AT89S52 microcontroller. Please remember to use an optocoupler to isolate the microcontroller pins from any direct electric contact with the motors, and also use a current amplifier to avoid toasting your optocoupler.

Code: Select all

#include "reg52x2.h"

/*

* FUNCTION_PURPOSE: This file set up timer 0 in mode 2 

* with a software gate.



duty = (256-RL_OFF)/[512-(RL_ON+RL_OFF)]

*/



#define fCrystal 20000 /* in kilohertz */
#define fPWM 1 /* rotation speed in RPS */
#define Instr_Per_Cycle 12
#define Duty 100 /*percent*/

#define RL_ON_C (256 - Duty * fCrystal / fPWM / Instr_Per_Cycle)
#define RL_OFF_C (512 - RL_ON_C - fCrystal / fPWM / Instr_Per_Cycle)

unsigned char RL_ON = RL_ON_C, RL_OFF = RL_OFF_C; 

bit flag = 0;
unsigned char stat = 1; 

unsigned int count = 0;



void main(void)

{

TMOD &= 0xF0; /* Timer 0 mode 0 with software gate */

TMOD |= 0x02; /* GATE0=0; C/T0#=0; M10=1; M00=0; */

TH0 = RL_ON; /* init values */

TL0 = RL_ON;

ET0=1; /* enable timer0 interrupt */

EA=1; /* enable interrupts */

TR0=1; /* timer0 run */

P2_0 = 0; /* Initialize P2.0 */

while(1); /* endless */

}





void it_timer0(void) interrupt 1 /* interrupt address is 0x000b */

{

TF0 = 0; /* reset interrupt flag*/

if (flag == 1)

{
TH0 = RL_OFF;
if (stat == 0)
{
P2_0 = 1;
P2_1 = 0;
P2_2 = 0;
stat = 1;
}
else if (stat == 1)
{
P2_0 = 0;
P2_1 = 1;
P2_2 = 0;
stat = 2;

}

else if (stat == 2)
{
P2_0 = 0;
P2_1 = 0;
P2_2 = 1;
stat = 0;

}
}

if (flag == 0)

{

TH0 = RL_ON;

}

count++;

if (count == 1000)

{ 

if (P1_0 == 0) RL_ON++;

if (RL_ON >240) RL_ON = 240; // Upper limit

if (P1_1 == 0) RL_ON--;

if (RL_ON < 16) RL_ON = 16; // Lower Limit

RL_OFF = 512 - RL_ON;

count = 0;

}

flag = ~flag;



} 

[Neo]

why cant i post links???

You should be now
https://robot.lk/viewtopic.php?f=36&t=2597&p=7630#p7630

I have also enabled syntax highlighting by using 'syntax' tags instead of 'code'. This was introduced recently and announced under news. Please check Portal -> BBCode help -> Syntax Highlighting.

As you clearly noticed, you need to start a new topic for each different question/article. Have a look at How to connect CD-ROM motor to PIC microcontroller?. I think both are similar.

Rksk,
In you post, it mention as that motor can achieve 30K RPM. This is not usual with Steppers (According to my knowledge).
BLDCs are available in such high RPMs.