I have successfully powered the Nano and EasyDriver controller with a 12V wall outlet, letting the 5V Nano lane to power the rest of the stuff.
I read that 12V for a Nano is a bit on the high end and inefficient. It has an AMS1117-5.0 marked to provide the 5V, but being a cheap chinese clone anything is possible. Would it be better to power the EasyDriver and Nano at 9V? Would I lose torque on the stepper mottor doing so (I will be using it at low speeds)? Would it be better keeping the 12V input and adding a few diodes to lower the voltage input to the Nano?
Edit: the motor will be powered off most of the time, engaging maybe 3-4 times a day for a few seconds.
It would be better to power the Nano with a 12V to 5V DC to DC converter (buck converter) connected to the 5V pin. That will bypass the weak onboard 5V regulator.
I think powering off of the 12V is just fine that will give you the best noise immunity. to be way safe be sure the devices you connect consume less than 50 mA in total. The regulator iI think s rated at 800mA but at that point the solder holding it to the board will melt. I would not exceed 100 mA load on the 5V pin. Without the specifications for each item I am only guessing but I expect you to be under 50 mA. Check the temperature of the regulator to be safe.
Your stepper is high-impedance. This means it won't go very fast and needs more than 12V into
the EasyStepper to get its rated torque.
With modern stepper drivers you use low impedance motors (around 0.5 to 3 ohms), since
the drivers are current-sourcing. Having a low impedance motor and a driver running from
a high voltage allows much faster operation of the motor (1000rpm perhaps, rather than
the 100rpm or so you'll probably get with that motor).
The basic issue is that stepper motor performance is governed by inductance, not resistance,
and low impedance motors have far lower inductance.
In general , whenever possible , I would avoid using a motor power supply as an input for a logic circuit 5V regulator. Just bad practice. Motor and logic supplies should always be separate and never shared. (like Eggos)
raschemmel:
In general , whenever possible , I would avoid using a motor power supply as an input for a logic circuit 5V regulator. Just bad practice. Motor and logic supplies should always be separate and never shared. (like Eggos)
Thanks for the insight. What is the problem exactly, noise from the motor into the Arduino? Could you give me some pointers on how to fix it?
Yes, noise , but it consists of spikes on the dc power rail caused by inductive surges .
Only way to 'fix it' is don't do it. You can try large
amounts of capacitance ,like 470uF to 1000uF or
more, even 1 F super capacitor, depending on the motor. I'm not it can be eliminated. You would
have to just keep adding electrolytic caps until
hopefully , at some point, the interference with
logic circuits is eliminated , if ever.
Your LCD ? Forget about it. It's going to go crazy
when the motor starts and stops. Total batshit
crazy. Good luck with that...
sharing a power supply is Not advisable.
Can you eliminate all the noise by adding enough
filter caps ? That's one bet I wouldn't take.
I don't understand how this can be such an impossible task. There are plenty of 3D printers, CNC machines, manipulator robots, etc. using just one plug to power both their stepper motors, electronics and displays.
I might be lucky, but as I said in my first post, I have already built and tested this project on a breadboard with a 12V power supply and I have not detected any issue so far. The LCD also works fine when the motor engages.
I don't understand how this can be such an impossible task
Look at the schematics for those machines !
Not ONE of them has a single DC regulator !
They may have as many as five different regulators
and they ALWAYS have a SEPARATE motor power
supply. Typically they have one rectifier circuit to
supply unregulated filtered DC, either 12V or 24V
or both. These PRIMARY supplies provide the input
voltage for a bank of SECONDARY regulators, +5V, +12V, -12V, or even -5V, depending on wether
they have bipolar op anp sensor signal conditioning
circuits. The motor always has it's OWN motor
power supply for the motor driver. The microprocessor and all the 5V logic ( either TTL or MOS) have their OWN 5V power supply. If you are
(as I strongly suspect) , an electronics newbie, it
behooves you to learn basic electronics BEFORE
messing around with electronic circuits. (Udemy.com). If you want something pkug and play, buy a toaster. A pilot is not going to jump in and take off without flight training. Anyone with
any electronics experience already knows everything I just told you. Why you think you can
use electronics with no electronics experience is a
mystery.
(Just fir the record, I have done many stepper motor arduino projects, always using a separate
12V regulator for motor power) Just get a DC2DC
converter and use your 5V as input to that . It
may provide enough isolation to eliminate the
unwanted noise. Ideally, using the 12V supply
as input for TWO dc2dc converters, one adjusted to the correct output voltage for the stepper and the other adjusted to 9V for the Nano Vin input, would be the preferred approach, providing isolation from the
5V circuits while providing THREE layers of regulation for the 5V:
Layer-1: 12V PS
Layer-2: dc2dc converter adjusted for 9V dc output
Layer-3: Nano onboard 5V regulator
Thank you for the explanation, Raschemmel, I found it very interesting (and everybody else for their suggestions too).
As for my background in electronics, it is mostly theoretical and the reason why I am doing these small projects now is in part to learn how things work in real life and in part because I always had fun with mid level programming.
So maybe you can get away with using one 12V P.S. for motor and microprocessor raw Vin
but it's much more reliable to have the main 12V serve as Unegulated Raw DC and have
separate regulators for logic and motors. It usually eliminates any noise problems.