first of all I will explain my situation:
I am developing a project in wich we need to be able to control the vibration frequency of a motor. In our first approach we intended to use an Excentric Rotating Mass motor, but then I saw this Motor:
I thought I could control it´s vibration frequency using pwm and a precision potentiometer. Not knowing how to measure the intended vibration I asked in an electronics forum but then someone answered my questions saying that coin vibration motors only operated at certain frequencys. After that, I have done better research and found out that this motors only operate at a small specific range of frequencys and also that it is recommended to use them at resonant frequency... My problem is that I contacted the support team of gearbest and they told me that I was able to drive the motor at the frequencys I intended.
Does someone know if I can put the motor to vibrate in a frequency range between 30~150 Hz with the motor mentioned above and if so, do you know how can I measure the frequency of vibration?
It is not possible to "set" a certain frequency with those. They can run slower and faster, but the range is indeed limited. At low speed they vary a lot. For higher speed you need to overvolt them.
Another problem is the PWM frequency. That will interfere with the motor.
It is hard to get a single vibration frequency.
What is it for ?
If you want a resonator at a specific frequency, perhaps a solenoid can be used.
We are very thankful to your reply! We are making a device with biomedical application. We really need to produce a vibration in wich we can modify it´s frequency. We do not know yet what frequency is best but we know it is between 50 and 125 Hz more or less. I think we will need to go back to our initial idea of using an ERM motor. What do you think?
An other thing I forgot to mention: If the vibrating motor runs slower for a lower frequency, the vibration is weak. With higher voltage the vibration is strong. The 150 Hz could be 10 times stronger than the 30 Hz. This is just a guess, I have used them in the past but I forgot most of it.
There are very small tube-alike ERM motors. They have the same problems.
You could try to buy a number of different types and test them.
Search AliExpress for: vibrating motor
A larger ERM motor, for example for massage cushions, are easier to control.
The surface transducer mentioned by @Wawa is a good idea when you are developing a project and don't know the best frequency yet.
It is the same idea as the solenoid that I mentioned. If you want to make a mechanical frequency, then use a component that can do that.
