beginner building wired robot

[kaushik]

I wish to know the circuit to control right left reverse forward movement
of the 2 MOTOR robot without using a microcontroller and only 2 switches(DPDT).
Is it possible using gates like EX-OR or NAND gates

[Admin]

Without a microcontroller?

Well the circuit would be the H-bridge:
http://www.societyofrobots.com/schematics_h-bridgedes.shtml

But you need 4 switches for each motor . . .

[Handmixer.com]

Assuming you wish to have an umbilical cord running between you and the robot, the two switch scenario actually IS possible. What you have to do, is wire up a DPDT switch as explained below. one switch per motor.

Firstly, solder a wire diagonally from the bottom left pin of the DPDT switch, to the top right pin of the same.

Secondly, solder another wire on, this time from the bottom right to the top left.

Thirdly, solder the motor to the two central pins and two wires from a power source to the top left and top right pins.


This setup is most effective if you use momentary centre off DPDT switches.

[Admin]

hmmm ok DPDT is technically 2 switches . . . but yea handmixer is right, you only need two DPDT's . . .

[EngineerGG]

Assuming you wish to have an umbilical cord running between you and the robot, the two switch scenario actually IS possible. What you have to do, is wire up a DPDT switch as explained below. one switch per motor.

Firstly, solder a wire diagonally from the bottom left pin of the DPDT switch, to the top right pin of the same.

Secondly, solder another wire on, this time from the bottom right to the top left.

Thirdly, solder the motor to the two central pins and two wires from a power source to the top left and top right pins.


This setup is most effective if you use momentary centre off DPDT switches.

Hello everyone.
My name is GG. I'm a second year Electrical and Electronics Engineering student. This is my first ever post. And i've brushed into robotics a little (attened an orientation program)

Handmixer, i couldnt quite understand your 3rd point. I'm going to use the method stated above for my robot. Its going to be wired. I'm using differential drive (obviously). and like u said, one DPDT switch with the spring for one motor (stepper motor, thats what i'm using.).

Basically, if i thrust the DPDT to the upper pair of terminals, i want the wheel to spin in one direction and if i thrust it to the lower pair i want it to move in the opposite direction, how will doing what you said give me that effect?

Could you please explain with a diagram?

PS- sorry for the long post. This is my first robot ( i know its crap )and i have to finish it in 5 days ( 5 days left)

Thanks in advance
^_^
GG

[Conscripted]

I found these links that may help
http://www.instructables.com/id/HOW-TO:-Wire-a-DPDT-rocker-switch-for-reversing-po/
http://www.instructables.com/id/How-to-make-an-H-bridge/

Conscripted

[EngineerGG]

Thank you Conscripted. I found the video link for the H-Bridge cool

And few more major questions. What happens when you connect a supply directly to a stepper motor? Can it be run directly run like a DC motor or is it compulsory to have the stepper motor controller circuit. and I have an IC called the ULN 2003 AN. Is that the stepper motor driver? Can you tell me how to use it?

Now i'm really worried. My foot-ball robot has to have a supply of 12V 3A (D.C). It should be <= 25cms x 25cms.

and finally, what is an RPM motor? what does it do?

Thanks

GG

[SmAsH]

stepper motors have poles, google it.
you cannot run it like a dc motor, it requires a driver circuit.
no idea google for a datasheet on that part "ULN 2003 AN".
rpm is a measurement of speed. it stands for revolutions per minute.

[EngineerGG]

stepper motors have poles, google it.
you cannot run it like a dc motor, it requires a driver circuit.
no idea google for a datasheet on that part "ULN 2003 AN".
rpm is a measurement of speed. it stands for revolutions per minute.

Well smash, i know that much about steppers, but thats my whole point, i've never used it. Is there a tutorial on how to MAKE a driver circuit.
Correct me if i'm wrong.
1. The driver circuit will have a 555 timer to send signals to the motor uC that runs the stepper.
2. Everytime we press a movement key on the remote control(if there is one). The timer send the signal to the motor driver to drive the stepper.

lastly, i know what RPM is, but what is an RPM motor.( not RPM OF a motor). and i think they might be called geared motors. what are they?

Thanks
GG 

[jka]

I haven't heard the term RPM motor before, but a geared motor is a motor with a built in gearbox (or a motor+gearbox). What you get is a lower RPM from the gearbox, but a higher torque. The result is, that the motor with a gearbox will have enough power to move your robot, but if you put the wheels directly on a non-geared motor, the wheels will spin fast in free air, but they will not have enough torque or power to move the robot.