12v and 5v power supply

[peeg]

Hi guys,

Back again, got most of the supplies for my first build, just figuring out the electronics part now.

The led buttons I have require 5v power, and the coin mechs I will order require 12v.

I'm attaching a molex/daisy chain for the buttons to my old pc's power supply which I guess will do the 5v ok? For the 12v, do I need a separate power source or can I use the same PSU and the wires or something regulate the voltage?

 Just want to check and order if so so I have it ready after I've finished the other stuff.

Cheers!

[big10p]

... or can I use the same PSU and the wires or something regulate the voltage?

What do you mean by this?

[peeg]

Haha not too sure, I have zero electrical knowledge.  Was wondering whether something in the wires or the actual cable connector or whatever that plugs into the PSU can change the voltage from 5 to 12v or vice versa, or a power supply basically outputs one or the other and there's no way to change it?

Like if a PSU outputs 12v, is that ok for 5v and 12v things? Does it automatically downgrade or change to 5v rather than pump 12v into a 5v thing (does that even matter?) 

[big10p]

If you have a switching PSU (one that outputs more than one voltage), you need to connect the positive (+) input terminals of your 12v devices to the 12v output on the PSU, and connect your 5v devices to the 5v output, separately. You can however connect all the negative terminals of your devices to a single ground (GND) on the PSU, if you wish.

[aldub516]

I hope im understanding your problem and i hope this makes sense.. if you have a power supply with an extra molex plug, the red wire is 5v, the yellow wire is 12 volts. just trip them down, and run the red to the 5v, the yellow to the 12 v and all the black wires are ground

[Titchgamer]

I hope im understanding your problem and i hope this makes sense.. if you have a power supply with an extra molex plug, the red wire is 5v, the yellow wire is 12 volts. just trip them down, and run the red to the 5v, the yellow to the 12 v and all the black wires are ground

^ This.
A PC PSU outputs several voltages but the ones you require are as stated above.
Yellow for 12V and Red for 5V.

Just plug in or butcher a molex and you will be fine.

[Mike A]

Please take the time to learn some basic electronics before you mess with this. You will save yourself money, aggravation, and possibly a nasty shock.

[peeg]

Please take the time to learn some basic electronics before you mess with this. You will save yourself money, aggravation, and possibly a nasty shock.

Cheers guys. Understand Mike, last thing I want. Asking simple questions like this hopefully to understand it all better and know what I'm doing before I attempt anything.

So as I understand it, the PSU outputs both 12v and 5v and it's simply the wiring that differentiates between the voltages, yellow for 12v, red for 5v - no need for any other power source?

[Phreakwars]

Correct. And you can source off the same molex connector. Invest $2 and buy one of these

http://www.newegg.com/Product/Product.aspx?Item=N82E16812423187

Splice into the extension instead of the power supply. That way if you ever want to or need to switch the power supply out, you won't need to splice anything, just unplug the old one and plug in the new.

EDIT: if you want SATA, then get this one: http://www.newegg.com/Product/Product.aspx?Item=N82E16812400144

[05SRT4]

Please take the time to learn some basic electronics before you mess with this. You will save yourself money, aggravation, and possibly a nasty shock.

Cheers guys. Understand Mike, last thing I want. Asking simple questions like this hopefully to understand it all better and know what I'm doing before I attempt anything.

So as I understand it, the PSU outputs both 12v and 5v and it's simply the wiring that differentiates between the voltages, yellow for 12v, red for 5v - no need for any other power source?

Most PSU's will output both. Every MAME build I have done I have never had to use multiple PSU's unless I needed the power requirements.
Red 5v Yellow 12v
To be completely sure though you should invest in a cheapo voltmeter.
And please please please make sure that everything is unplugged when working on it.