how many servo motors can be connercted to arduino uno r3 with knob control
At least as many servos as you have knobs (assuming knob means potentiometer)
If knob means potentiometer and you want to control each servo independently then the problem is not how many servos you can connect but how many "knobs" you can connect. There are not many analog pins.
Steve
sanket79:
how many servo motors can be connercted to arduino uno r3 with knob control
The Servo library supports 12 servos for the Uno (not servomotors, you are confusing a servo mechanism
with a servomotor, an altogether different beast). Servomotor - Wikipedia Servo control - Wikipedia
If you want individual knob control for each, an external analog muliplexer like this: SparkFun Analog/Digital MUX Breakout - CD74HC4067 - BOB-09056 - SparkFun Electronics
will allow enough analog channels.