Probably a stupid question but I'll ask anyway

[matt]

I have a couple of projects in mind, the first is to put my pi with hifiberry dac in a nice aluminium case.
I was thinking of using this for the power supplyhttp://www.ebay.com/itm/5V-2A-10W-AC-DC-Universal-Regulated-Switching-Power-Supply-/111476024693?pt=LH_DefaultDomain_0&hash=item19f47d2575
Will it be ok or are there better options?
I also was intending to put a power button on the front panel - http://www.ebay.com/itm/12V-16mm-Auto-Car-LED-Power-Symbol-Push-Button-Metal-Latching-Switch-Aluminum-/111281662724?hash=item19e8e76b04.
The power supply is 5v and the power button is 12v so I'm guessing this wont work?
I'm open to any and all suggestions, I dont really know what I'm doing.
Thanks
matt

[Fishstix]

Hey Matt,

There are never any stupid questions. Least you can do is learn, right?

This power supply looks like the same as someone on these forums who did more or less what you are trying to accomplish. Rating looks correct, anyways, assuming you are going to be using 120v in? If you are using 240, it looks like you'll be working with somewhat less current output.

I think you're right about that switch as well... 5vdc *probably* won't be enough to light up a 12vdc LED set. Did some scrounging, and you can find this classy little thing at Digi-Key. (Lil' pricey, maybe you can find a better deal somewhere else.) But it has a ring that lights up at 2.8vdc. So you should be good there.

http://www.digikey.com/product-detail/en/PV7F2T0SS-341/EG4735-ND/2116214

If you are looking for some ideas, check out http://www.runeaudio.com/forum/tpa3116-runeaudio-project-t319.html.

Skrodahl and a few of the others have been working to do the same thing as you. And the photos coming out of it are *inspiring.* I may do one of these some day.

First page of the thread has what looks like this switch light, and page six has a photo of the power supply in an enclosure. Good ones to see how they laid it out.

Best of Luck!
Fishstix

[matt]

Cheers for that Fishstix.
I have had a look at the other thread you mentioned. Wow some cool stuff going on there.
So I have now found a new 5v switch http://www.adafruit.com/products/482 and as I am on 240v, a different power supply http://www.ebay.com/itm/AC-100V-240V-DC-5V-5A-Adjust-Universal-Regulated-Switching-Power-Supply-25W-New-/350944322084?pt=LH_DefaultDomain_0&hash=item51b5e96224
I'm good to go with these, right?

[Fishstix]

I know, right? Some very clever, talented people here.

A way better price on that switch, and supporting the good folks at Adafruit. I like your style. I am hoping to build an integrated Rune/El84 tube amp at some point, I'll need to keep this switch in mind. So clean! And with 13mm thread length, I could put it through a wood surround.

Power supply looks peachy to me, I am sure folks will pipe up if I've got it wrong, but with 5A to play with, you shouldn't ever have to worry about a brownout on your board. In one of the photos on that thread, you can see that there are solder points on the DAC where you can input 5v directly. My HiFiBerry DAC+ has the same setup. It should feed both boards, negating the need to snake a microUSB cord, and burn precious chassis space. If the spacing is right, you could solder a screw-point jumper instead, making re-work easier. My HiFi DAC+ has 5v pin spacing that looks dead on at 3mm, and the below item is 3.5mm, it's probably what I'll do when I get around to it.

http://www.digikey.com/product-detail/en/OSTTE020104/ED2740-ND/2351816

Anyways, photos as you go along!

-Fishstix

[skrodahl]

I have the same PSU and power button. That the LED is 12V means that it will glow the brightest at 12V. It may very well light up at 5V, I can test it tomorrow if you'd like. I lowered the brightness considerably on the button on my amplifier build. If I hadn't it would be far too bright.

The Adafruit power button is probably better suited anyway, as you can lower a LED but not make it brighter with a given voltage.

I would go with the smaller PSU if I were you. If nothing else, just for space considerations. You might need those extra 4+ amperes for something else. Go with the smaller one if not. Brownouts can be (to some extent) mitigated with a, let's say 1000uF/25V, electrolytic capacitor between +5V and ground. The larger PSU most probably doesn't much larger capacitance on the output than the smaller one.

[Downunder55]

I also was intending to put a power button on the front panel - http://www.ebay.com/itm/12V-16mm-Auto-Car-LED-Power-Symbol-Push-Button-Metal-Latching-Switch-Aluminum-/111281662724?hash=item19e8e76b04.
The power supply is 5v and the power button is 12v so I'm guessing this wont work?matt

I have a very similar one to you also 12v rated LED and just checked it and it lights nicely at 5V

[Peter]

I also was intending to put a power button on the front panel - http://www.ebay.com/itm/12V-16mm-Auto-C ... 19e8e76b04.
The power supply is 5v and the power button is 12v so I'm guessing this wont work?
I'm open to any and all suggestions, I dont really know what I'm doing.
Thanks
matt

Hi Matt

I see skrodahl and Downunder55 have already answered - quick off the mark they are!

I power my pi's with a repurposed ATX computer power supply - this offers the benefit of being cheap, relatively well regulated, and you have access to both 12v and 5v rails, which could solve any issues. However, this necessitates an external supply which might not suit your configuration, but it is an alternative.

[matt]

Thanks everybody for the replies.
skrodahl - i've looked up the capacitor you mentioned, how would i wire this in between the +5v and the ground? Would I only need this for the larger power supply? Am i in danger of "blowing something up" with the larger power supply?
At this point I only intend to have to power the pi and dac, the led switch and possibly a wifi dongle on the pi usb. is the smaller power supply sufficient?
Downunder55 - Hi, from across the ditch . Thats good to hear about the switch lighting up with 5v. I like the symbol and the combination of the green led - green for go. So ill get this one and if it doesn't work out Ive only lost a couple of bucks.
Peter - thanks for that suggestion but I am only wanting an internal power supply, at this point.
Thanks again everyone, I' ll have some more questions soon no doubt.

[skrodahl]

skrodahl - i've looked up the capacitor you mentioned, how would i wire this in between the +5v and the ground? Would I only need this for the larger power supply? Am i in danger of "blowing something up" with the larger power supply?
At this point I only intend to have to power the pi and dac, the led switch and possibly a wifi dongle on the pi usb. is the smaller power supply sufficient?

Hi matt,
Just skip the capacitor, it was just me rambling about brownouts. Unless you have serious brownout issues, just go with the power supply as is. (Yes, the capacitor can blow up )

I've successfully run a Raspberry Pi with both a USB DAC and a USB wireless network card on a 0.8A power supply. 2 amperes will be sufficient. The LED in your switch will require less than 10 milliamperes, I'd call that negligible.

Good luck with your build, and chime in if you need any more help, assistance or suggestions.

Did you already have a case in mind for your project?

[matt]

Ok, so I have ordered a switch, the 2a power supply, and external rj45 and usb plugs with extension cables. The last two items are just to allow all options when I finally put it together and they were cheap so if I dont use them I'm not too concerned.
I am yet to find a case I am happy with. I'm tempted to use the same one a skrodahl has used for his hifiberry build (in the TPA3116 thread) but I would like a little more spare space just to make things a little easier.
I also like the way skrodahl has removed the rca terminals from his dac and just wired them up. I would like to do this if possible, is it easy to remove the rca terminals? Is this a good idea? I can possibly take it to a local electronics guy and have him do it for me if its tricky.
Thinking ahead I have another couple of noob questions.
Whats the best way for attaching the board to the case?
Do I need to isolate (insulate?) the pi from the case, I cant imagine I can have the pi sitting on the case with all the solder points in contact with the metal case. Whats the best way to do this?
Thanks