New way to power up your computer-based cabinet

[bfauska]

I wanted to power up my cabinet using a button on the CP w/o having a dedicated button for the task. I know that some motherboards will allow you to use a keyboard key to power-up the PC but mine doesn't. So I decided that with a relay I could choose a button on my CP and wire it to the motherboard power-on header and when the PC was powered the button would become the "Enter" button for use in my front-end. I shut down the cabinet by shutting down windows from MAMEwah with a shifted key combo, so I didn't need the power button to be connected once the computer was on, but I did leave the original power button wired to the MB before the relay so it stays functional at all times, this way I can use it to power down if the computer locks up or something. In the future I plan on using the empty poles of the relay to switch a power strip for the speakers and marquee and for illuminating the power button when the cabinet is off and then allowing LEDwiz control of the LED in that button.

Here's a picture of how I wired up the relay. I think the picture should be pretty clear, but if there are any questions feel free to ask. Hopefully somebody will find this useful.

[Major Rock Hardy]

nice idea!

I am right at this point now, trying to figure out what relay I needed to buy to have the mobo turn on the monitor, and you give me this idea for a power button!

So about the relay:  12V coil (obviously), but is it a DPDT?  The picture almost looks like a 4PDT.  Anyway, do you have problems with oscillations of the coil?  Power pops when the coil field breaks down?

Also, is that terminal block a relay socket or is it part of the relay?  Can you post the relay part #?

I am also interested in delaying the power-on (and off) of the speakers because the monitor can make a pretty loud pop in the speakers.  I think I'm going to make an RC charging circuit and a comparator for this but I'm throwing it out there for comments.  Time delay relays are silly expensive.

Cheers,
MRH

[bfauska]

The relay is a 4PDT relay mounted in a socket. I think it's from Grainger, I ordered some 24v ones last year at work to replace these so these got ditched and I grabbed one. The 4P will work out nice in the end for me because of all the things I want it to switch. The coil hasn't been buzzing or oscillating at all and I haven't noticed any pops. I'm not switching anything powered with it yet though so there's not really anything that would pop.


I think this is the relay. I could look at the part number on the relay, but I'd have to open my cab, I know this is one I would order to do it again, I just don't know for sure that it is THE same relay.

[DaOld Man]

Neat idea bfauska!!!

I like using relays.. I used to use relays to do all sorts of complex functions on machines at work, then the end of the world was ushered in by the PLCs.. 

Still, you would be surprised what you can do with a few relays.

[bossyman15]

i just do it easy way all i did was wire one of my button (pause) to motherboard so that button have 2 function 1) to power up the cab 2) to pause the game
i just set it up in windows so pressing power button does nothing. it will not power down. its pretty easy way to do it.

[bfauska]

I hadn't even thought about that. It is much simpler, but I think I like that I still have the ability to use the stock power switch to power off if I want (since I left it wired before the relay and I didn't change my windows or BIOS power switch settings.)

The relay will also come in handy to switch over from a static LED to LEDwiz controlled and for powering up the rest of the components w/o a smartstrip.

I do feel silly for not even thinking of that solution though, even if I wouldn't have used it, it should have occurred to me.

[ark_ader]

i just do it easy way all i did was wire one of my button (pause) to motherboard so that button have 2 function 1) to power up the cab 2) to pause the game
i just set it up in windows so pressing power button does nothing. it will not power down. its pretty easy way to do it.

Well pressing the power button on my pc shuts it down, so I think that idea will depend on your mobo. I used a AT PSU for the externals of the cab and let the ATX handle the PC with the same idea of having a switch to power up/down the machine. 

I placed the switch on top of the cab out of reach. 

You could use your cab as a server and leave it on 24/7.

[BobA]

Just a suggestion.   You should have a diode across the coil to reduce the rev emf when the relay is switched off.  This takes the spikes generated by the relay coil and shunts them to ground.  The diode is usually an 1n4007 or greater that is wired across the coil.   

See protection diodes for relays http://www.kpsec.freeuk.com/components/relay.htm

[bfauska]

Thanks, I'll look into that. What is at risk if I don't do it? The computer's PSU?