Hello, I want to use a stop motor to rotate a a circuit board continuously, the problem is not the step motor, but the light weight circuit board to put on top of the step motor for rotation. It is too heavy to put the power source with circuit board, so the circuit board has to get power else where, not to be attached to it. The problem arises, the circuit board need to attached to the + and - wires of the power source, are there some sort of rotation contact available for the rotation with getting the two wires tangle up? Thanks.
The normal way to do that is to use "slip rings", do a search for them.
Powering rotating circuits is either expensive or unreliable 
Another normal way is moving everything into the stationary part. Why do you need electronics on the turning PCB?
Or think of a RC model with wireless control, that acts on top of the motor without any external power source.
DrDiettrich:
Powering rotating circuits is either expensive or unreliableAnother normal way is moving everything into the stationary part. Why do you need electronics on the turning PCB?
Or think of a RC model with wireless control, that acts on top of the motor without any external power source.
I agree it is likely to be a source of failures. The issue here does not seem to be control, which could be done wirelessly as you suggest, but the power supply.
This slipring is not too expensive and is rated for 2A
https://www.robotshop.com/uk/slip-ring-flange-736.html?gclid=EAIaIQobChMI27_4y8_e2AIVbL7tCh3orgwOEAYYASABEgJL5_D_BwE