Please bear with me, I am new to electronics so my question may be stupid, but I want to make sure that the system is safe and won't catch fire.
I am trying to use an A4988 driver to power a stepper motor. The system is currently working pretty well, the stepper motor is rotating when I tell it to, but I have a safety concern over the use of a capacitor in the circuit.
This is the A4988 driver https://www.amazon.co.uk/gp/product/B0793K9KF8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I've been following tutorials such as this one https://www.makerguides.com/a4988-stepper-motor-driver-arduino-tutorial/ and they all mentioned the capacitor between VMOT and GND.
The DC source in this picture is regular 12V adapter plugged into a wall socket.
The stepper motor and the A4988 driver are rarely used in the project and I am hoping to completely turn them off when I am not using them.
My questions are:
- If I am not using the motor, is it safe to have the capacitor there while electricity still flows through the wires? Won't it create a short circuit?
- When I am not using the motor, won't the capacitor draw power from the adapter? I'd like to minimize power consumption as much as possible. Especially since the motor will only be used 2-4 times a day tops. The answer provided here Is it acceptable to leave a capacitor across batteries even when turned off? makes me think that the capacitor will draw a little bit of power. I would like to eliminate this completely, if possible.
- Should I just add a relay to this to cut the flow of electricity completely when I don't need it? If so, does it matter if I put it before the VMOT and the capacitor(point A in the diagram), or after the capacitor and the GND of the A4988 (point B in the diagram)?
Best Answer
A or B technically don't matter in most cases but A is best since B is being used as the reference. It matters more for high voltage when everything is earthed to B so disconnecting B would make everything float and be unsafe.