setpper motor

[abdullahseba]

is there a stepper motor controller that has a switch for making the motor going forwards & backwards without using any programing

[Simon]

You mean you want a forward / reverse pin ? yes I think they do many of them. The pin can be brought high or low by am MCU or a simple switch.

[GeoffS]

Most stepper motor drivers have  STEP, ENABLE and DIRECTION lines as input.
More detail of your intended application may help.

[poorchava]

Stepper motors are typically used when positioning is needed. If you only need to spin motor forwards and backwards, perhaps you should pick a normal DC motor?

[Witention]

I assume that the stepper motor has gears that reduce the 45 degree movement of the armature to only 1.8 degrees of movement on the drive shaft.The gear down ratio is 25 to 1, amplifying the drive force between 20-25 times - including friction loss. Am I correct??

[tjb1]

I assume that the stepper motor has gears that reduce the 45 degree movement of the armature to only 1.8 degrees of movement on the drive shaft.The gear down ratio is 25 to 1, amplifying the drive force between 20-25 times - including friction loss. Am I correct??

No, they work with magnetics.

[Kremmen]

I assume that the stepper motor has gears that reduce the 45 degree movement of the armature to only 1.8 degrees of movement on the drive shaft.The gear down ratio is 25 to 1, amplifying the drive force between 20-25 times - including friction loss. Am I correct??

Like tjb1 stated - no gearbox. The most common type i.e. variable reluctance motor has both rotor and stator equipped with protruding square teeth (looknig along the motor axis). The number of teeth is different such that when one phase the stator coils are energized, say A, some teeth align providing a minimum reluctance magnetic path through the rotor. When the next phase B is then energized, a successive set of teeth is puuled into alignment causing torque on the motor shaft. Next reverse energize A and you get the next step and so on and so on. The number of teeth is cleverly calculated to provide just the desired angular displacement per step.
Read alla bout it here: http://www.pcbheaven.com/wikipages/How_Stepper_Motors_Work/?p=0

[poorchava]

I assume that the stepper motor has gears that reduce the 45 degree movement of the armature to only 1.8 degrees of movement on the drive shaft.The gear down ratio is 25 to 1, amplifying the drive force between 20-25 times - including friction loss. Am I correct??

What you are referring to is called 'a servo'. It's typically a motor with a gearbox, an encoder and a position controller. Type of controller and motor vary. RC servos typically swing within limited range and are driven by pulse train with constant frequency and variable on-time. Industrial servos can typically spin around like a normal motor and they utilze wide variety of motors: DC, AC, brushless. Other types too, but more rarely.