I thought of connecting a solenoid to a motor board. It will be a DIY motor with one static solenoid and a rotating thing with permanent magnets. And a Hall sensor.
The motor board I'm using accepts a Vcc of 4.5 - 6 V and the max output on one channel is 1.5 A. The voltage drop in the motor output is 0.2 V. So if I connect 4.5 V, I get 4.3 V out. The max current of 1.5 A means that the multimeter measured resistance of the solenoid must be at least 4.3V/1.5A = 2.87 Ohm. Am I on right track here? The 1.5 A would be the stall current. My DIY motor might not even start to rotate by itself, it might need a helping hand. So I have a big concern for not exceeding the 1.5 A.
I am always reluctant to use any piece of electronic equipment close to its stated maximum unless it is clearly stated to be a continuous rating. For most hobby parts the rated values are the absolute max.
A solenoid is different from a motor because it has nothing other than the coil resistance to limit the current. A motor generates a back-emf when it starts to rotate and that acts against the supply voltage. It is why the stall current of a motor is very much higher than the running current.
You may find it difficult to get a solenoid with a low current and a low voltage that has enough force.
Would a small servo be a suitable alternative for the solenoid?
I remember having a salvaged linear actuator somewhere. I took it from an old cd player. It had this moving coil around a stationery iron core. The coil might have enough resistance for this project.
The electromagnet will make a fidget spinner rotate. The fidget spinner will have magnets at its three "wings". I place the spinner on a box. Inside the box is the electromagnet switching poles. N - off - S - off - N - off etc.
