I have a DC Servo motor (12V) with only two inputs, when i connect the 12V at its inputs, then it moves in one direction, and when i reverse the polarity, then it moves in the opposite direction. My question is that what are the types of servo motor, is there any servo motor with two inputs, if yes, then what is the difference b/w this servo motor and DC motor? Reply plz. Excuse my english.
Servo is a motor application, not a motor type. In your case, it's obviously a brushed DC motor.
I agree with the Wikipedia definition: "A servomotor is a motor which forms part of a servomechanism". In principle, any motor type can be for it, depending on the speed, power, and control precision requirements.
As i have no idea of shelf servo, so it will be a little bit difficult for me to use it in my project, and the above stated motor is like a dc motor, that's why i want to use it. if you have some to the point supporting material, programing techniques and some pictures and diagrams, then please mail me or send me a link. i will use shelf servo. thanks
You didn't provide the necessary design requirments (tourqe, speed, temperature etc...) for your valve actuator so it's hard to recommand a servo.
Please review this link for an of the shelf HOBBY GRADE servo. **broken link removed**
Hobby grade actuators (like the one in the link) have the motor/power electronics/feedback/controller all integrated in a single case with only cables connected to it (Vcc, Ground and PWM control signal.
It's typical rotation range is +90 to -90 degrees. I've seen some kits that can convert them to linear movements though.
Please remember that these are HOBBY GRADE and shouldn't be considered for high reliability uses such as: Life supporting devices, cold fusion reactors, putting a man (or dog) on Moon/Mars, etc...