PCB mounted mains power supply for arduinos.

Hi,

Up till now, all my arduino projects have been battery powered. My latest needs to be mains (240v) powered and I want the power supply to be PCB mounted rather a mains adapter. Can anyone tell me if this is suitable?

I'm not sure if its a regulated supply, or just a small transformer with a rectifier and capacitor?

thanks

That appears to be a complete (AC to DC) power supply. The only thing that makes me nervous is that they call it a "transformer".

The [u]datasheet[/u] properly identifies it as a power supply.

or just a small transformer with a rectifier and capacitor?

A switching power supply is a bit more complicated than that... It's got a high-frequency oscillator that "switches" (oscillates) in a feedback-loop, regulating the output voltage. The high frequency allows them to use a physically smaller transformer and a smaller-value filter capacitor.

There is a schematic in the datasheet, and that doesn't show any security measures at all. No fuse, no MOV ...

I should make a template for this: - Don't do it, you will kill yourself and your beloved ones - Use a USB charger instead - If you REALLY have to do it: o Care for proper strain relief, nobody wants a ripped out mains cable hanging around o Care for proper touch protection an protective earth o Look at this. I belief it is similar to the thing you found there - Don't do it, you will kill yourself and your beloved ones. And no insurance will pay. There is a reason why most devices have external power supplies.

Use a USB charger instead

The reason I wanted to use this was because I wanted to avoid using a USB power supply - they're notorious for bursting into flames, also they rarely include fuses which I had intended to include with the above component.

There is a reason why most devices have external power supplies

As I look around my office, the printer, computer, radio, desk lamp, stereo and telly all plug directly into the mains. Only my laptop and phone use an external power supply. Are they really so dangerous?

no MOV

What is a MOV?

thanks

Fulliautomatix: Hi,

Up till now, all my arduino projects have been battery powered. My latest needs to be mains (240v) powered and I want the power supply to be PCB mounted rather a mains adapter. Can anyone tell me if this is suitable?

I'm not sure if its a regulated supply, or just a small transformer with a rectifier and capacitor?

thanks

This is a subject that if you have to ask relativly basic questions, its more than likely you dont have the experience to put all the bits together in a way that is safe.

Which is why the recommendation will often be to buy a ready assembled external power supply that meets all the required safety and insulation requirements.

ElCaron: There is a schematic in the datasheet, and that doesn't show any security measures at all. No fuse, no MOV ...

That's a block diagram, they don't show the schematic because its their intellectual property.

This is a properly rated supply from a reputable supplier with all the relevant safety standards: "Meet all requirements of UL/CUL60950, EN60950, EN60335, EN61558‐2‐16,CE,VDE, and ENEC Mark"

I should make a template for this: - Don't do it, you will kill yourself and your beloved ones - Use a USB charger instead - If you REALLY have to do it: o Care for proper strain relief, nobody wants a ripped out mains cable hanging around o Care for proper touch protection an protective earth o Look at this. I belief it is similar to the thing you found there - Don't do it, you will kill yourself and your beloved ones. And no insurance will pay. There is a reason why most devices have external power supplies.

The point is you have no defence in law if you use this in a piece of kit you make, but its way better than using a knock off unsafe chinese USB supply, because it won't catch fire or electrocute you unless you do something really dumb. A properly rated external USB supply is going to be the best of all worlds because you don't touch the mains and its a safe supply.

its way better than using a knock off unsafe chinese USB supply, because it won't catch fire or electrocute you unless you do something really dumb.

that's what I thought.

A properly rated external USB supply is going to be the best of all worlds because you don't touch the mains and its a safe supply.

Perhaps I ought to have mentioned that the project involves turning on and off a mains voltage fan - so I will be playing with mains voltage (which I do have some experience of)

This is a subject that if you have to ask relativly basic questions, its more than likely you dont have the experience to put all the bits together in a way that is safe.

The fact that the proposed part appears to be correct for the described purpose suggests some relevant experience. If the OP had proposed using a (insert random component here) then I would be a lot more worried.

OhMyCod: The fact that the proposed part appears to be correct for the described purpose suggests some relevant experience. If the OP had proposed using a (insert random component here) then I would be a lot more worried.

Well although the part is well described and pictured in the link provided, the OP did say;

"I'm not sure if its a regulated supply, or just a small transformer with a rectifier and capacitor?"

Which did rather suggest a lack of knowledge in this area.

For me I gave up using my own internal mains setups some years back, these days its just so much easier to power stuff from an 12V external supply. These are available at low cost, as are internal stepup\down switching regulators.

That's a block diagram, they don't show the schematic because its their intellectual property.

THEY title it with schematic. Allow me the inaccuracy to do the same. In any case, I would expect the mentioned components listed there, if they WHERE there.

MarkT: This is a properly rated supply from a reputable supplier with all the relevant safety standards: "Meet all requirements of UL/CUL60950, EN60950, EN60335, EN61558‐2‐16,CE,VDE, and ENEC Mark"

Safety standards for what? To be a part of a power supply, or to BE a power supply?

MarkT: The point is you have no defence in law if you use this in a piece of kit you make,

If your 400k€ house burns down, some defense in law for your insurance is a very good thing.

MarkT: but its way better than using a knock off unsafe chinese USB supply, because it won't catch fire or electrocute you unless you do something really dumb. A properly rated external USB supply is going to be the best of all worlds because you don't touch the mains and its a safe supply.

When someone wants to built a power supply and asks what a MOV is, I dispute that. Of course, YOU can find a less safe supply. But if you go for some at least vaguely reputable manufacturer (I feel those who sell stuff that works with things like quick charge tend to be reasonably engineered) you will be much better off.