Thanks for the replies!
The device in question is a massage device with an off center weight. It works as follows: I lay down on the bed and put the vibration part between the mattress and my back. It can be operated just by me so I don't need a second person to hold it.
Why are you using an Arduino for this? There do not seem to be any controls to the pwm speed and no control for the motor direction. Will there be a pre-set program for the Arduino to follow?
I got a free Uno when I ordered some other parts, I can get a different one if I need to. The PWM signal is to be controlled with a knob. It's gonna translate the knobs 1024 positions into 255 PWN signal with the code. I just haven't put it into the diagram yet. This is a vibration motor so I don't need to control the direction.
I also want to include a shut-off circuit with an NTC thermistor probe. That was to be my next question. The motor is rated at max 50C so it has to shut off after the 30mins that I need it to run or when it reaches ~45C. I think that's a safe number.
I guess that the motor driver electronic is powered from the motor source, should not cause problems if the Arduino is down or disconnected, or if power is removed from the motor.
But I also wonder what you want to move using a 1.1W motor?
The motor has a built-in driver and it has to move an off-center weight and work against all the forces from the outside, against my back.
Just wondering, what makes you think you can build a more robust one?
Do you know really why those commercial ones broke down, and how to overcome those problems?
My previous devices were not designed for this type of function, they were built from cheap, low quality components, I repurposed them. There are also no medical grade massage units that fit my requirements, that I could buy instead of making them.