I would like to use an ATX case for AT motherboards, but I have found it difficult to mount the AT power button to these ATX cases. How difficult would it be to make a soft on-off switch circuit to power on the ATX PSU if used with an AT motherboard?
wrote:I would like to use an ATX case for AT motherboards, but I have found it difficult to mount the AT power button to these ATX cases. How difficult would it be to make a soft on-off switch circuit to power on the ATX PSU if used with an AT motherboard?
AT power switches have AC line power through them. They are on-off switches.
ATX power switches don't and couldn't handle the current. They are momentary switches.
You said ATX case with AT motherboard but I'm not clear on which type PSU you want to use.
You are talking AT switches but then said "to power on the ATX PSU".
An AT switch wouldn't normally be used with an ATX PSU so pardon my confusion.
Most AT PSUs do not have a standby voltage so soft-off isn't an option without designing an AC powered relay circuit of some kind.
There are a rare few that do have a standby rail (internally) and those have extra wires/connectors for the power switch.
Related discussion just a few weeks ago: AT power supply with soft-off?
I've seen configurations where an AT PSU used a push type on-off switch mounted near the back of the case and that was activated by a reach-rod that passed through the case to the front panel where it ended in a button.
Is a lot of creative fabrication but that might be your solution.
Also a commercial push switch could be mounted to the front metal and a hole put through the plastics to activate it.
With some effort it could be made pretty.
Regarding AT switches.
If you go custom make sure to get the proper type (DPST) and volt/amp rating of switch.
A DPDT is sometimes used and would work but isn't needed and it just makes the switch bigger.
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/\ He is using and ATX PSU with a converter. That is a lot easier to handle than trying to retrofit an AT PSU.
The easiest route here is to salvage a latching button (like the one used in turbo buttons in AT cases) and replacing the switch behind the power button with one of those. That is a very simple mod, all you have to do is to solder the wires to the button.
wrote:/\ He is using and ATX PSU with a converter. That is a lot easier to handle than trying to retrofit an AT PSU.
The easiest route here is to salvage a latching button (like the one used in turbo buttons in AT cases) and replacing the switch behind the power button with one of those. That is a very simple mod, all you have to do is to solder the wires to the button.
Then why is he trying to use an AT power button in an ATX case?
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You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
wrote:/\ He is using and ATX PSU with a converter. That is a lot easier to handle than trying to retrofit an AT PSU.
The easiest route here is to salvage a latching button (like the one used in turbo buttons in AT cases) and replacing the switch behind the power button with one of those. That is a very simple mod, all you have to do is to solder the wires to the button.
Here is an image of a ATX case power button. You press it down and then it gets up back when you release.
Are there actually similar buttons with same dimensions that will keep their state? So if I press it down, it would stay down until I press it again. I have not found any and don't know what these buttons are called, so can't buy them. But it would solve the problem very easily.
wrote:wrote:/\ He is using and ATX PSU with a converter. That is a lot easier to handle than trying to retrofit an AT PSU.
The easiest route here is to salvage a latching button (like the one used in turbo buttons in AT cases) and replacing the switch behind the power button with one of those. That is a very simple mod, all you have to do is to solder the wires to the button.
Here is an image of a ATX case power button. You press it down and then it gets up back when you release.
Are there actually similar buttons with same dimensions that will keep their state? So if I press it down, it would stay down until I press it again. I have not found any and don't know what these buttons are called, so can't buy them. But it would solve the problem very easily.
So what you really want is a push on-off switch to replace the momentary ATX switch?
Those should be easy enough to find (at electronics shops, not PC shops) but they aren't called AT switches.
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So what you really want is a push on-off switch to replace the momentary ATX switch?
Those should be easy enough to find but they aren't called AT switches.
This would be the easiest way. Then I would not have to modify the ATX case and I could use an ATX power supply with the adapter cable.
wrote:Here is an image of a ATX case power button. You press it down and then it gets up back when you release.
Are there actually similar buttons with same dimensions that will keep their state? So if I press it down, it would stay down until I press it again. I have not found any and don't know what these buttons are called, so can't buy them. But it would solve the problem very easily.
That is exactly what I was talking about. Turbo buttons in AT cases use buttons with the exact same dimensions, but latching (will stay on until you press it again) instead of momentary. Get one of those and you are set.
What are the dimensions?
Length-Width-Height of the block and the Length of the activation rod.
In mm would be good.
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wrote:wrote:Here is an image of a ATX case power button. You press it down and then it gets up back when you release.
Are there actually similar buttons with same dimensions that will keep their state? So if I press it down, it would stay down until I press it again. I have not found any and don't know what these buttons are called, so can't buy them. But it would solve the problem very easily.
That is exactly what I was talking about. Turbo buttons in AT cases use buttons with the exact same dimensions, but latching (will stay on until you press it again) instead of momentary. Get one of those and you are set.
I hear ya.
Fine if you have one handy but AT cases with turbo buttons go for $80 and up around here unless you get lucky and find one at a garage sale.
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I believe they are pretty much standard. Once I had to replace a latched switch in an AT case and all I did was ask for a latched switch at the nearest store and it worked just fine.
Yes, there are standard replacement latching switches with identical dimensions to the momentary stitches found on those PSU converters. I have a bag of them. Forget the part number.
BUT, if you want to have a little fun, you can turn a momentary switch into a latching one with a dozen or so discrete components. See my PCB and circuit diagram here, Re: Cyrix MII-433GP Build
Plan your life wisely, you'll be dead before you know it.
Here's the same thing using a flip flop. Make sure the flip flop outputs a low rather than hi-Z.
viewtopic.php?f=25&t=45740&p=459657#p459669
As noted, I haven't tested this circuit. It may need capacitive debounce. Aside from a toggling relay, this is the simplest option I can think of.
All hail the Great Capacitor Brand Finder
So far as ATX switches fitting a given case,
I've come across square ones, rectangular ones, long ones, short ones, big-little and I think even round ones.
There have been a number of times I've had to glue something to the push-rod on a replacement to make it long enough to function in whatever case.
There is a most common size, but I can not tell in a photo if that's it.
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The Turbo switches from AT cases tend to have the same form.
1+1=10
I am currenting working on two similar projects. One is an AT motherboard in an AT case, but using a modern ATX power supply instead. The other is an AT motherboard inside an ATX case with an ATX PSU.
For both projects, I am using this passive ATX to AT adapter, which converts the ATX power connector into an AT connector, including -5V if your ATX PSU supplies -5V (mine do). It contains two female spade connectors for the ATX soft-off connectors, with the idea being you connect those to the case's power switch. One complication is that it uses smaller width spade connectors so it won't fit a standard AT power switch.
To solve that elegantly for the AT case, I have purchased these AT power switches which have small male spade connectors on them, and have the same mounting dimensions as an AT power switch. This lets you power the ATX supply on and off using the AT case's power button, and it feels heavy when you press the button, just like the old AT switches used to.
For the ATX case, I have seen many switch variations but the particular cases I am using have those small square switches as shown in the photo above. They appear to be simply called 8x8mm switches, and here's an eBay seller offering 10 of the latching ones you'd want for $1.25. I happened to have a couple of these already from some old AT cases I cannibalised back in the early 90s (from the turbo buttons as others have stated), so I could substitute them in without any problems to turn the ATX power button into a latching switch. I have yet to decide how to connect these to the ATX soft-off spade connectors, as I don't have any small male spade connectors handy and I'm not so keen on cutting them off in case one day I want to move the converter somewhere else. I'll probably make some kind of spade-to-0.1-inch connector, since the replacement latching switch already had cable with a "TURBO SW" connector on the end of it.
One thing worth noting is that the soft-off wires in the ATX-to-AT converter are only 21cm long, which is fine in my AT cases, but it would be too short to reach the power switch in the ATX ones - so probably just as well I need to build a converter!
sorry to revive an old thread but I thought I'll ask here instead of creating a new one.
I am in exactly same situation, I want to use a modern ATX pwoer supply in an AT case. I bought the ATX to AT adapter which comes with the two green/black wires to connect a power switch.
What I am still no clear on is what type of switch am I connecting to those wires? a momentary or latching switch ? The AT case has clearly a latching switch meaning the two wires will be constantly connected when the switch is flipped. However, I thought ATX power supplies only need a single press/connection to get powered on so only a momentary switch should be used. However above poster says they connect this directly to their AT case which has latching switch so I am bit confused.
Thanks.
Omarkoman wrote on 2024-11-05, 00:41:sorry to revive an old thread but I thought I'll ask here instead of creating a new one. […]
sorry to revive an old thread but I thought I'll ask here instead of creating a new one.
I am in exactly same situation, I want to use a modern ATX pwoer supply in an AT case. I bought the ATX to AT adapter which comes with the two green/black wires to connect a power switch.
What I am still no clear on is what type of switch am I connecting to those wires? a momentary or latching switch ? The AT case has clearly a latching switch meaning the two wires will be constantly connected when the switch is flipped. However, I thought ATX power supplies only need a single press/connection to get powered on so only a momentary switch should be used. However above poster says they connect this directly to their AT case which has latching switch so I am bit confused.
Thanks.
in this case, sine you are using AT case, you can simply re-use the old AT latch switch with the ATX-AT adapter.
In ATX mainboard, when you push the button, the super i/o chip will pull the PS-ON pin (the blue wire) to ground and hold it so that the PSU can start (and those chip get the power from the 5V standby). With ATX-AT adapter, you will connect PS-ON to ground manually and that what the latch are using for.
That makes sense, thank you.
It’s the green wire.
You can even just jump that from the ATX connector, through the AT front panel switch, to ground.
