Hello,
wondering what is the cheapest and possibly simpler way to set a fixed speed (precision doesn't matter) on a DC Motor without PWM of Arduino. I am going to use a lot of them (motors) so this could also reduce the overall cost.
Thank you
Hi,
How big is the motor, Watts, Volts, Amps?
How many?
What is the application?
Thanks.. Tom... 
maronid:
set a fixed speed (precision doesn't matter)
Does that mean the actual speed in rpm doesn't matter, as long as it's constant?
But then....
I am going to use a lot of them (motors)
... do they all have to be at the same speed, whether or not the actual speed matters?
The actual speed of a DC motor depends on many factors. That's why the actual speed must be measured and run through a PID before it can be used for a PWM signal controlling the H-bridge of the motor.
With stepper motors it's possible to control the speed immediately, provided that they are not overloaded and loose steps.
Hello again,
I am going to use 16 of them. 5V. Not sure about Amps yet but generally small ones like the ones we can find in small toys. Speed of each one of them deferent but fixed. The precise rpm is indifferent. It is going to be used for musical purposes.
You can try to have a small resistor in series with each motor, in order to make each motor turn at different speed. Find out yourself. No guarantee that it will fit your expectations.