Connecting power supply

Newbie question, I'm working on a project that involves motors and I'll need to use a wall plug power supply for the first time. How do I go about connecting the power supply to the rest of the electronics?

The power supply has a 5.5mm jack, giving me 19V/6.5A. From that I need to power 2 stepper motors, 2 servos and possibly the Arduino (though I may power that via USB). I'll use a step down module to give me 5V for the servos.

What's a sensible way to hook all this together? (I'm talking about the physical aspect here)

I'm looking on eBay for a female power jack, but most of them are rated at 12V/1A. I'll keep looking.

From the female jack, I'll need to split the cable to send power to the stepper drivers (EasyDriver) and to the step down module. Any advice on how to do that? Is there any particular gauge of wire I should use?

vaspoul:
The power supply has a 5.5mm jack, giving me 19V/6.5A. From that I need to power 2 stepper motors, 2 servos and possibly the Arduino (though I may power that via USB).

It's a laptop power supply.

vaspoul:
I'll use a step down module to give me 5V for the servos.

And the Arduino. The on-board regulator is pretty much useless.

vaspoul:
What's a sensible way to hook all this together? (I'm talking about the physical aspect here)

I'm looking on eBay for a female power jack, but most of them are rated at 12V/1A. I'll keep looking.

You won't find one.

That is because that is the standard rating for that connector. Laptops have for better or worse, utilised these for way more current - the voltage rating is irrelevant. They are frequently flaky; I have on more than one occasion resorted to disassembling the laptop and wiring the power cable directly to the PCB, so you could well consider cutting off the connector and doing likewise.

Otherwise just use these:

Or if you are building it into a box, these:

That is as good as it is going to get.

Actually, these look more rugged:

Thanks for the replies!

I decided to use an Arduino CNC shield as this simplifies a few things. This at least answers my power adapter question. From what I can see, people using this shield don't seem to use any step down board. They hook up the 12V input of the shield onto the Vin of the Arduino. Is that what you were advising not to do? i.e. I should go from power supply (12v) -> step down module (5V) -> Arduino?

The shield also has a 5V output, but I suspect that's just the Uno's 5V output. Provided I'm powering the Uno from an external power supply, am I ok to use that to drive 2 servos? From what I can see it should be able to provide 1A.

vaspoul:
I decided to use an Arduino CNC shield as this simplifies a few things. This at least answers my power adapter question.

In fact, many of the people providing advice here have not used more than one or two of the available "shields" for the UNO form factor. And that would include myself. So when you refer to something like "an Arduino CNC shield", you need to provide a link to the full description of the module to which you refer.

vaspoul:
From what I can see, people using this shield don't seem to use any step down board. They hook up the 12V input of the shield onto the Vin of the Arduino. Is that what you were advising not to do? i.e. I should go from power supply (12v) -> step down module (5V) -> Arduino?

Well, 12 V is the absolute safe limit of what you can supply to Vin, but you cited a 19 V power supply.

vaspoul:
The shield also has a 5V output, but I suspect that's just the UNO's 5V output.

Which would indeed be pretty useless.

vaspoul:
Provided I'm powering the UNO from an external power supply, am I ok to use that to drive 2 servos? From what I can see it should be able to provide 1A.

This external power supply is supplying a regulated 5 V? Two servos have a stall current near 2 A, so you really need a 5 V 2 A supply. A switchmode converter of that output rating should be able to deliver that from 19 V (or 12 V).

Sorry, yes, I was going to use a 19V power supply until I decided that using a shield and following other people's examples is a better match to my (in)experience!

The shield I'm planning on using is this : Arduino CNC Shield – 100% GRBL Compatable | Protoneer.co.nz

People seem to connect a 12V power supply to it and use that to drive both the Arduino and a servo.

I'm not sure how they get away with using the 5V pin to drive the servo. As far as I can tell (and I don't have one in my hands yet) the 5V pin on the shield is just an extension of the one on the Uno.

I'll give it a try and see what I get. (my project uses 2 servos but I'll try powering one to start)

I've also ordered a step down module (https://bit.ly/2n9Q3lA) which should give me 5V 3A from a 19V power supply. I'll try using this to power both the servos and the Arduino and drive the steppers at 19V (which I read is better in some way).

In terms of physically connecting the output of the step down module to the servos and the Arduino, how should I do it? Do I solder multiple wires on the output? Use some kind of connector (e.g. https://bit.ly/2M1jZOU)? Use a power distribution board (e.g. https://bit.ly/2OIGTJn)? Splice the wires (e.g. How To Splice Wires to NASA Standards - YouTube)?

vaspoul:
Sorry, yes, I was going to use a 19V power supply until I decided that using a shield and following other people's examples is a better match to my (in)experience!

The 19V supply is entirely fine if the CNC shield, the motor drivers on it and the steppers will handle that voltage.

vaspoul:
The shield I'm planning on using is this.


This certainly has no electronics. You would want to check the capacitor voltage ratings. I haven't checked to make sure that it does not connect "Vin" to the UNO.

vaspoul:
People seem to connect a 12V power supply to it and use that to drive both the Arduino and a servo.

I'm not sure how they get away with using the 5V pin to drive the servo. As far as I can tell (and I don't have one in my hands yet) the 5V pin on the shield is just an extension of the one on the Uno.

Well, they would need to provide a 5 V supply with sufficient current capacity to drive the servos. The on-board regulator on the UNO does not even count for such a consideration.

vaspoul:
I'll give it a try and see what I get. (my project uses 2 servos but I'll try powering one to start)

Give what a try?

vaspoul:
I've also ordered a step down module which should give me 5V 3A from a 19V power supply. I'll try using this to power both the servos and the Arduino and drive the steppers at 19V (which I read is better in some way).

The switchmode regulator is slightly more efficient at the higher voltage, and requires less current. That one should be OK.

vaspoul:
In terms of physically connecting the output of the step down module to the servos and the Arduino, how should I do it?
Do I solder multiple wires on the output?

Perfectly fine. Note that you need to connect both ground and supply from the same source, running as a pair to each device.

vaspoul:
Use some kind of connector?

Fine, but not too easy to connect more than one wire to each terminal! Need to twist and tin the wires (if using multi-strand) before connecting. The better quality (than that pricey one) "chocolate block" strips have a metal tongue under the screw to protect the wires from crushing.

vaspoul:
Use a power distribution board?

If it is convenient. Grossly over-priced at that site!

vaspoul:
Splice the wires?

Interesting video. Didn't get to the end (yet - got to go to work now :astonished: ) but need heatshrink over each splice.

Thank you for all your replies!

What I meant is that I'll try the 12V route, powering one servo off the 5V pin on the shield and see how it goes. Then I'll probably look at trying with 19V.

As far power distribution boards go, I've designed one myself and sent it off for fabrication via the service Fritzing provides (Your Fritzing Sketch manufactured by AISLER). I found them to give pretty good rates.

Paul__B:
Actually, these look more rugged:

Physically rugged, probably. But a pain to solder a wire to the center pin. You must insert the plug before soldering to hold the pin in place while soldering because the plastic is low melting point stuff and allows the center pin to move. Really a POS.

Paul

Just like doing RF connectors, eh?