Saturday, June 15, 2013

Stepper Motor Rotation ( 172.5 degree angle ) without any Microcontroller

Stepper motor is an electronics device and a brushless DC electric motor that divides a full rotation into a number of equal steps. It is widely used in robotics, industry, computer peripherals, motion control, business machines and many other purpose. 

There are many techniques for rotating stepper motor. We need to rotate motor any angle that we want. We know that stepper motor is one kind of digital device or digital motor, for rotating this need sequential clock pulse to the specified coil of the motor. For rotating 360 degree angle need specific number of clock pulse which is depends on the number of coil and its mechanism. 
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Most of the people use microcontroller for rotating stepper motor any angle and speed. Using microcontroller, stepper motor’s speed control and any angle rotation is very easy, accurate and flexible work. For microcontroller must need to know assembly or embedded C language. 

The students who are new or beginners, does not know these language is very difficult to make project related to stepper motor rotation. This topics will help them to solve the problem without having microcontroller knowledge. Because the topics is “stepper motor rotation any angle without microcontroller.” 

Though it is quite hard, students will be benefited by this hobby project. This project is fully hardware implemented and design is complicated on the clock IC section. The following project description is given bellow – 

Required instruments:
  1. Timer IC- 555 timer – 1pcs
  2. Flip-flop IC – 74109 - 1pcs
  3. Clock IC – 7490 – 2pcs
  4. AND gate IC – 7408 – 1pcs
  5. Jonson Counter – 4017 – 1pcs
  6. Motor driver IC – 293 -1pcs
  7. Relay – 6 volt – 1pcs
  8. Transistor – BC547 -1pcs
  9. Resistors – 150k, 10k and 1k - 2pcs
  10. Capacitors – 4.7 uF, 10nF
  11. Diodes – 4148 – 1pcs
  12. IC driver voltage – 5 Volt
  13.       Motor driver voltage – 9 Volt
Stepper Motor:
These stepper motor have 4 pin so have 2 coil. Pin-1 and Pin-3 have one coil. Pin-2 and Pin-4 have another coil. Motor have 48 steps so need 48 pulse for 360 degree rotation. So motor rotate 7.5 degree angle per step or per pulse. The stepper motor internal coil configuration is given bellow:
 So the pulse sequence will be Pin-1, Pin-2, Pin-3 and Pin-4. The stepper motor is connected to motor driver IC 293. 

Motor Driver IC:
For driving motor, need huge current. Jonson counter IC cannot deliver huge current to operate the stepper motor. For this reason motor driver ic is needed. IC293 is called motor driver ic which need 2 different voltage one is 5 volt and the other is motor driving voltage 9 Volt or 12 Volt.  Pin-9 will be connected to 9 Volt or 12 Volt and Pin-16 will be connected to 5Volt. Pin-1 and Pin-9 will be short and connected to 5volt with 10k resistor. Pin-4, 5, 12, 13 is connected to ground. Pin- 3, 6, 11, 14 are output and Pin- 2, 7, 10, 15 are input which are connected with 2nd Jonson counter IC 4017. 

Clock Pulse Generator:
This is the 555 timer based clock pulse generator which is called astable(free running) multivibrator. The output frequency is 1Hz which is fed to the Jonson counter (both IC Pin- 14) and clock IC (first IC Pin-14).
2nd Jonson counter (HC4017):
Jonson counter is a decade counter which have ten output pin and one input clock pulse pin. When clock pin-14 get pulse then the counter deliver pulse sequentially to the ten output pin. Here we need only 4 pin so the reset Pin-15 will be connected to Pin-10. So the four output pin of the counter are Pin-3, 2, 4, and 7 sequentially. Which will be connected directly with motor driver ic.
 N.B: Jonson counter ic driving voltage must be 5volt.

1st Jonson counter (HC4017):
Similar to 2nd Jonson counter only the difference is 1st Jonson counter’s output will be connected inversely to the 2nd Jonson counter’s output. Clock Pin- 14 of both ic will be connected to the clock pulse generator IC 555 output Pin-3.
N.B: Pin-16 of both IC are voltage pin connected to the 6 Volt relay. 6Volt relay supply the voltage alternatively to the two Jonson counter IC.

Clock IC (SN74LS90N):
SN74LS90N is mainly counter IC used for making digital clock in laboratory work that’s why it is popular as clock ic. Two 7490 are using here to get 23 pulses for rotating 172.5 degree angle. AND Gate IC (7408) is also used here. This circuit diagram is given bellow:

 N.B: If you need to know how it works please visit here. IC driving voltage must be +5volt if greater ic not work accurately.

Flip-flop (74109):
This is the  flip-flop IC which is configured as a T flip-flop. T flip-flop output depends on the input (which is come from the 7409 ic). Pin-2 and 3 is connected to the output of the SN74LS90N IC. And the output pin-6 is connected to the transistor BC547.
When input is 1 the output is 1 and when input is 1 the output is 0. Again
When input is 1 the output is 1 and when input is 1 the output is 0.

 If is most important that every 23th pulse clock IC(SN74LS90N) give one pulse. So the output of the Flip-flop will be 1 and 0 alternatively on every 23th pulse. Using this technique transistor will be ON and OFF according to Flip-flop output. And also active and de-active the relay alternatively.

Relay:
The main function of relay is to supply the positive voltage (+5volt) alternatively to the Jonson counters (Pin-16). When 1st Jonson counter (HC4017) will get the voltage, the motor rotate 172.5 degree clockwise direction and when 2st Jonson counter (HC4017) will get voltage, the motor rotate 172.5 degree anti-clockwise direction. 


Any Angle:
By changing clock IC pulses we can change the angle of the motor rotation.

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