AT style signal to ATX style

[zpsyx9]

So I have a gutted NES with it's AT style toggle switch. I'm going to be building an atx system inside of it and I was wondering if there's a way to get a "single pulse" from the power switch's toggle. I would like to keep this PC as close to the NES' functionality as possible, and I'd like to keep the switch as is. I have a little bit of soldering and digital logic / IC experience but not a whole lot with finding actual ICs so a little help on the subject would be appreciated. I know you can remove the latching pin in the button, but I'd like to know if there's a way to keep it. I am also aware there is no way to get the EXACT functionality of the NES but i'd like it to pulse the ATX header when i press the power button and again when i release it.

Not sure if this is highly technical but I guess it's above the norm for a regular PC enthusiast.

 

[PottedMeat]

Isn't the RESET switch on an NES momentary? Could you just use that?

http://www.allelectronics.com/...ITCH-ASSEMBLY/-/1.html

The switches look similar, if you've got another one, you could just replace the POWER with another RESET switch and keep the button.

 

[cheesehead]

You want a circuit called a "one-shot".

http://www.circuitdb.com/show.php?cid=107

 

[mindless1]

There may be an easier way. Simply cut the PS-On signal line from the ATX connector in the middle, wire both ends of that lead to the switch so it completes the circuit when it's on, and turns the system off then switch is flipped off. Main drawback is you no longer have to ability to have a modern OS turn off the system, it'll be necessary to flip the switch to do that.

Maybe I've overlooked something and this won't work but at worst you simply solder both ends of the PS-On wire back together with a piece of heatshrink tubing covering it and you're back where you started.

 

[Aluvus]

Originally posted by: PottedMeat

Isn't the RESET switch on an NES momentary? Could you just use that?

http://www.allelectronics.com/...ITCH-ASSEMBLY/-/1.html

The switches look similar, if you've got another one, you could just replace the POWER with another RESET switch and keep the button.

Yes, the Reset switch is momentary, the Power switch is push-on push-off.

I bought a bunch of the linked assemblies once long ago, and can confirm that the two switches have the same dimensions, but are configured slightly different internally. IIRC, the push-on Power switch can be opened up and turned into a momentary switch by removing a single part, but I don't have any at hand at the moment.

If you can strip it down to just that assembly, it is trivial to pull the keycap off of the switches and swap them. The switches are held to the metal piece mostly be friction (you have to bend back some small metal tabs to remove them), so it wouldn't be difficult to replace the switch itself.

 

[zpsyx9]

I think I'm going to give that 555 circuit a shot, seems like that will give me the functionality I'm looking for. I can use the reset, or mod the ps switch to momentary, but if you look around mini-itx.com and such it's been done before. I have yet to see a modern PC built inside using the stock buttons / connectors as-is. (lol don't correct me)

Originally posted by: mindless1
There may be an easier way. Simply cut the PS-On signal line from the ATX connector in the middle, wire both ends of that lead to the switch so it completes the circuit when it's on, and turns the system off then switch is flipped off. Main drawback is you no longer have to ability to have a modern OS turn off the system, it'll be necessary to flip the switch to do that.

I'm not sure but I thought having the ATX power pins constantly shorted powers down the system shortly after boot. I'll look into that though.

 

[mindless1]

Originally posted by: zpsyx9
I think I'm going to give that 555 circuit a shot, seems like that will give me the functionality I'm looking for. I can use the reset, or mod the ps switch to momentary, but if you look around mini-itx.com and such it's been done before. I have yet to see a modern PC built inside using the stock buttons / connectors as-is. (lol don't correct me)

Originally posted by: mindless1
There may be an easier way. Simply cut the PS-On signal line from the ATX connector in the middle, wire both ends of that lead to the switch so it completes the circuit when it's on, and turns the system off then switch is flipped off. Main drawback is you no longer have to ability to have a modern OS turn off the system, it'll be necessary to flip the switch to do that.

I'm not sure but I thought having the ATX power pins constantly shorted powers down the system shortly after boot. I'll look into that though.

Having the motherboard power-on logic, the On Switch shorted, does turn off the system in a few seconds. Having the PSU PS-On signal line pulled down (with the switch) shouldn't turn the system off. The switch pins on the board control a circuit logic, are not directly shorting the PS-On signal line.