Recommendations for powering from AC (Canada)

Hello,

I'm working on a project where I have an arduino connected to various pieces of equipment, all on AC through a 4 port relay. We'd like this contained hardware to be all powered from a single power cord from a standard AC wall out let.

In Canada the standard wall outlet is 120V but there is a chance to hit as high as 240V in an odd case such as an oven or laundry dryer.

We don't want to have to wire in an off the shelf adapter to maintain neatness of the electronics. What I've been looking for is a module to convert our ac power to an appropriate DC value for the vin pin.

When looking here: voltage level - What are the 5V and VIN pins for? - Arduino Stack Exchange

It says the voltage should be between 7-12V. For sake of heat and life span I've been looking for 9V solutions.

This seems to be my most appropriate solution: Amazon.com

Am I correct or is there a better solution somewhere else or a better module? This one has no reviews but is literally the only solution I've found. There is this but it's only 5V and less than 1A: Amazon.com

All input is appreciated!

There are a lot of variables, here, so you could help us, to help you, if you followed the guidelines, outlined here:

http://forum.arduino.cc/index.php?topic=149015.0

Especially, a schematic would be nice -- if for no other reason, but to limit ambiguities and misconceptions when attempting to analyze your power requirements.

Pardon my frankness but that Amazon supply is classic Chinese no-brand junk. The real problem is you have zero idea of what you’re buying. The specs are vague and poor, but as expected for these types of rock bottom priced Chinese supplies, there are no agency approvals (CSA, CUL, ETL, etc).

Perhaps you should try looking at a real electronics distributor? Here is a very broad range of supplies that would power an Arduino and accessories. You’ll need to define exactly what you’re powering if you want help on selecting a proper amperage output.

9 volt wall warts on DigiKey

My Uno is powering an Ethernet shield, 4 port relay, SHT-20 temp/humidity sensor, MH-Z16 CO2 sensor, and an LCD 2x16 display.

Unfortunately my boss doesn't want to use wall warts. He's asked me to find a part that will accept an AC input (canada), convert to an appropriate DC value to power through the VIN method.

If 5v@2A is acceptable for a the barrel input, 9V@1A should be acceptable as it is only 1W difference. I could wrong, but now you have my hardware list powered by the Uno.

Other devices running parallel to the Uno off of the AC main line are an inline fan, and LED lights.

More frankness. You are blowing smoke about the standard wall outlet in Canada. The standard for ALL North America and South America is < 125 volts. And 60 Hz. More than that is not a standard wall outlet voltage. More than that requires a very different outlet that will NOT let a standard plug be inserted.

Paul

Thank you for your frankness. Yes I am aware of this. The location for the installation is not going to be in a home and there might be an instance of having larger voltages from standard shaped plugs. Both of the items I linked accept low and high ac values regardless.

So you obviously know the values of ac power in NA, but you intentionally ignored the question I was asking?

Which is, will devices such as the ones I linked provide sufficient power to my Uno over VIN?

The two previous commenters asked for additional information to help answer the question, which I supplied them.

I'd appreciate constructive input over deliberate abrasiveness. Thanks

I still have no clue what this is suppose to do besides to connected to AC devices and be powered by mains AC.

Do you mean what the whole unit and equipment is supposed to do? It's a grow room controlled over LAN

Or do you mean what the items I linked are supposed to do? It's intended to accept AC power (canada) and convert to appropriate vin power input values (7-12V).

Stay away from open frame supplies.
If you do use one, you are responsible to get certification, you will be libel for electrical problems fires etc.

Forget about universal power input.

Get a certified all in one unit with USB 5vdc @ 1-2A unit.

Use a USB terminated cord to power the project.

Unfortunately my boss doesn't want to use wall warts.

Then your boss knows nothing about electrical codes, standards and proper practices. Or, he’s just being obstinate. There is a reason why there are tens of thousands of wall warts on the DigiKey site and just about a hundred or so chassis mount supplies. Let that sink in for before reading further.

So let’s say you install an open frame switcher in your box. Now you have to provide proper grounding, fusing, switching and shielding. A major pain. That’s why they are so few open frame supplies and so many wall warts.

It’s all about meeting applicable codes. Period. There is absolutely no reason, IMO, other than ignorance, to avoid wall warts. Yeah, I know you can’t say that to your boss but maybe you could educate him in the way devices are properly powered in the year 2019.

If 5v@2A is acceptable for a the barrel input, 9V@1A should be acceptable as it is only 1W difference. I could wrong, but now you have my hardware list powered by the Uno.

Yes, you are wrong. Amps are amps. If you need 2 amps at 5 volts, you need 2 amps at 9 volts. A step down voltage regulator does not increase the current.

Thanks Larryd,

Could you link to an example of what you mean?

Do mean just a standard AC/USB cube? Or something that would take raw ac wires as input and have a female usb port as its output?

Thank you WattsThat! Very informative. I wasn't actually aware of grounding, fuses, and other things included in wall warts. I'll actually probably just show him your response.

As for how I'm wrong about my watts=va math.... I'm still unclear. I was under the impression that if you run 5V@2A into the barrel jack, yes you get 2A available to the uno. However if you run 9V@1A to the VIN pin I was assuming (yes I know what they say about assumptions) that the Uno then takes that down to 5V. And so 91=9W, 9W=5V*xA -> xA=9W/5V=1.8A. If this is not the case in how the uno works, is it shedding the extra 1A as heat leaving still just 1A available?

Lots of versions are available.

But there is not anything wrong with a wall wart!

Your math is fine. But, the wattage is not the same thing as amps. Lowering the voltage does not increase the available amps. You still have only 1 amp available from your 9 watt supply.

I know W are not A. Watts are the product of amps and volts. It must be lost to heat then.

Larryd, YES! Unfortunately I looking at the price of those (https://www.homedepot.com/p/Leviton-15-Amp-Decora-Combination-Tamper-Resistant-Duplex-Outlet-and-USB-Charger-Light-Almond-R08-T5632-0BT/205430297) it's much more practical to go with the Digi Key items WattsThat linked.

I'm just looking for the function of one of those usb ports. The two outlets wouldn't be used either.

Thanks! this has put me on the right track.

Is your phone not "neatness" because it has a wall-wart charger?

I have seen kits where the wall-wart is hidden inside. Regular 1/4" spade terminals go right onto the standard prongs of a NA plug. Of course if anyone opens up the enclosure, it doesn't look neat, but there's much worse available in cheap clones of popular equipment.

There's two kinds of voltage converter, if you're going from 9V to 5V. The onboard regulator on most Arduinos is a "linear regulator". That's the kind where a 2A output requires a 2A input. The waste energy is lost as heat. The other kind is a "switchmode regulator", sometimes known as a "buck regulator". That's the kind where 4W output requires only a fraction more than 4W as input, so the output current is higher than the input. Very efficient because it's not wasting power as heat.

Switchmode or "boost regulators" can output a higher voltage than input, so current will be less on the output side.

Thank you for your frankness. Yes I am aware of this. The location for the installation is not going to be in a home and there might be an instance of having larger voltages from standard shaped plugs. Both of the items I linked accept low and high ac values regardless.

This is not generally true. Having higher voltages on a standard wall outlet is not something that manufacturers spec out because it is indicative of a major electrical fault in the buildings wiring. If you were to run into this issue, almost every appliance and light bulb on the circuit would be destroyed...

So you obviously know the values of ac power in NA, but you intentionally ignored the question I was asking?

Also, you should note choosing to input mains power into your project greatly increases your companies liability in the event of a fault. I would make sure your boss is aware of that.

i agree with the comments suggesting use of a wall wart, but failing that I would suggest looking at meanwell power supplies on mouser or digikey.

Yes I have been told repeatedly. The only user to have presented information in a polite and non-abrasive manner has been WattsThat and larryd.

Together they have convinced me, by simply presenting new information, to use a standard adapter and to convince my boss of the same.

I'd like to let you know that the minute you start communicating in a condescending manner the information you are trying to communicate gets thrown out with the tone it was communicated with.

Don't talk down to others because you think you know more. I'm perfectly fine with learning and accepting new ideas, as demonstrated by this thread. However the way you have chosen to try and "help", if you can call it that, is not conducive to constructive input.

Have a good day Paul

so what you growing?

Just to distill this discussion:

  • If you need a solution that will work with multiple input voltages [e.g. 120VAC/24VAC], then you will need a "Switch Mode" power supply, one that outputs the 7-12V required for "Vin" on your Arduino. The lower the voltage the better, as higher voltages will cause more power dissipation, in the linear regulator--thus more heat. Heat can shorten serviceable life. Especially if this will be operated in a higher temperature environment. Look for supplies that either specify an input range that will cover all your cases [typically something like: 100VAC to 250VAC OR one offering the ability to change the wiring to accommodate the various voltages required. In the latter case, though, the supplies, on each delivered unit, will need to be altered in all cases where an input voltage is needed other than the default. This is an extra production step that can decrease throughput.
  • A "USB" supply will NOT provide a proper Vin solution. USB is 5V. Vin needs at least 7V.
  • Use of an external supply ["Wall Wart"/Desktop] is advised, to limit liability. BUT, the assumption has been made that that the OP's "Boss" lacks the facility and/or resources to properly implement an internal supply.
  • The power supply tends to be a "Weak Link" because it tends to be the most likely thing to fail. Thus, it makes sense to pay more for a reliable source.
  • A Linear regulator [like the one fed by Vin, on an Arduino Uno], will not increase available current. A 9V supply that can supply 1A, at 9V, will still only supply 1A at 5V. If the Uno used a Switch Mode Buck-Converter, [like on the Due], then, yes, the current capacity would increase: 9V*I[sub]in[/sub]``[tt][tt][tt]*[/tt]e [/tt]= 5V*Iout[/tt], where I[sub]out[/sub] will be greater than I[sub]in[/sub], tempered by the efficiency [e] of the Converter: Iout = (9V/5V)*Iin*e
    So, if the efficiency is 87%, and the current going into the Converter is 100mA, then the current being drawn by the 5V device being powered, will be: 100mA*(9/5)*.87 = [b]157mA[/b]