hardwire ATX switch

[Michael C]

Not at all, it was a realistic statement and you use the
term "impossible" only to further your arguement. What I
actually wrote was:

"The only way to soft-off a system and have it stay off,
contrasted with one with loss of power coming back on, is if
your bios supports it."

This was within the context of the system, not the system
PLUS homemade active circuitry added. I don't know about
you, but I find it rather foolish to suggest home-made
active circuits unless someone had expressedly asked about
them.

THIS WHOLE THREAD IS ABOUT HACKING AN ATX MACHINE!!!!

If we want to start talking about conceptually simple
circuits, then when someone asks something like "is my 200W
power supply enough", then someone could just respond "sure,
just swap in these simple parts changes to your power supply
like the transformer, diodes, inductors and caps". Simple
enough yes?

You are *really* pushing things now in an attempt to cover up what was
essential a false statement. Give it up for christ sakes.

Actually, I have a feeling you don't do many of these
"simple circuits" at all, because if you did, you would
realize that a conceptually simple circuit still requires
wading through parts lists, ordering, receiving, sketching
the circuit or being naturally adept at layout-on-the-fly,
constructing it, testing and interfacing it.

I've been making simple microprocessor circuits for 15 years. I don't know
much about analog circuitry or the more exotic digital stuff but I know I
could make this one with stuff from the local jaycar store (although I'd
have the parts in my cupboard). I suspect someone with a fairly basic
knowledge of analog circuits could make it a lot simpler, quicker and
cheaper than me.

This is all
for an old board that may be worth $10 and may or may not
have much usable lifespan remaining.

Did you read my post? As I said, it's not the cost of the existing board,
it's the cost of the new mobo, cpu and ram that you need to purchase to
replace it.

Unless you've been regularly perusing the parts lists at an
electronics house recently, or out of random luck you happen
to have them all in a bin in front of you, odds are good
that I'd have windows installed in same amount of time it
took to _actually_ order, receive and unpack the parts...
not even build anything with them IF you had had a circuit
in mind and the method of attachment, which so far it
appears you don't.

I'd use an Atmel 89c2051, a crystal, 7805 reg, couple of caps, an I2C eeprom
and possibly a tranny, diode and relay. I don't think you quite understand
how simple this circuit would be.

Michael

 

[kony]

You are *really* pushing things now in an attempt to cover up what was
essential a false statement. Give it up for christ sakes.

oh? it was a pretty clever cover-up to point out the extact
thing I'd written? OK, whatever...

I've been making simple microprocessor circuits for 15 years. I don't know
much about analog circuitry or the more exotic digital stuff but I know I
could make this one with stuff from the local jaycar store (although I'd
have the parts in my cupboard). I suspect someone with a fairly basic
knowledge of analog circuits could make it a lot simpler, quicker and
cheaper than me.

I do have a basic understanding of analog circuits and have
been building for years. I too fell into the trap you have,
thinking "oh it's a simple circuit", then when it comes down
to the details and actually _doing_ it, even a simple
circuit, done right, still takes a bit of time. Not a lot
of time, but put into perspective if OP had to get a board
and CPU, online it could be done for under $40, maybe even
nearly free at a local mom-n-pop computer shop.

Did you read my post? As I said, it's not the cost of the existing board,
it's the cost of the new mobo, cpu and ram that you need to purchase to
replace it.

The feature his board is lacking has been quite common for
several years as it wasn't even dependant on a board
manufacturer but was placed there by AMI or Award, already
built-in to most bios. One would have to pick an OEM board
or one quite old to not have a very good chance of getting
the feature if there were to randomly pick a board without
even bothering to check on whether it was supportive.
Naturally the older the board is, the lower the odds, but
this is not a feature that only became popular in the last 5
years.

I'd use an Atmel 89c2051, a crystal, 7805 reg, couple of caps, an I2C eeprom
and possibly a tranny, diode and relay. I don't think you quite understand
how simple this circuit would be.

Uh-huh.
I still think you underestimate the total cost in time and
$, that when all is said and done it's excessive for an old
motherboard. You're also talking about parts that you
(being familiar with them) might have at least a fraction
of, but OP likely doesn't. In other words I would
classify this more as a hobby or learning experience rather
than a prudent way to get the job done. There is a
difference of course- just because you "can" do something
doesn't always make it a good idea to do so.

 

[Michael C]

I do have a basic understanding of analog circuits and have
been building for years. I too fell into the trap you have,
thinking "oh it's a simple circuit", then when it comes down
to the details and actually _doing_ it, even a simple
circuit, done right, still takes a bit of time.

Maybe the first time you do it it takes a long time but I would have done
very similar circuits many times.

Not a lot
of time, but put into perspective if OP had to get a board
and CPU, online it could be done for under $40, maybe even
nearly free at a local mom-n-pop computer shop.

Now that sort of thing does take a long time, I've done it recently for a
couple of name brand PCs I purchased and it can be very hard to find a
second hand board that suits your processor and memory. I went round to
about 10 shops and one had a board but when I got it home it didn't take
ddr. Then there's the possibility that it won't have the power on feature
which will most likely not be common in the older boards. It could also be
faulty.

Michael

 

[kony]

Maybe the first time you do it it takes a long time but I would have done
very similar circuits many times.

Exactly.
When I do circuits like this, if I suspect I'll ever need
another one I go ahead and make them all at once. Helps
keep costs lower too as some parts are cheaper in volumes >=
10, 25, or 100 pieces.

Now that sort of thing does take a long time, I've done it recently for a
couple of name brand PCs I purchased and it can be very hard to find a
second hand board that suits your processor and memory. I went round to
about 10 shops and one had a board but when I got it home it didn't take
ddr. Then there's the possibility that it won't have the power on feature
which will most likely not be common in the older boards. It could also be
faulty.

On my last post I was just about to provide an example, I'd
Froogled for "motherboard" and found a few under $30
delivered that were socket 370, latter chipsets. Then
Froogled for "celeron" and found one for $4, others for
about $10 more. Such a combo would do the job, is about as
compatible as it gets being able to use PC66 through PC133
high-density memory, and practically all the name-brand,
non-OEM boards had the feature. I suppose it depends on the
rest of the need though.

It's fairly easy to see whether a board takes DDR just
looking at the slots- DDR has only one slot division (key)
that's off-center a little.

I suppose we have different perspectives as I'm often
picking up or otherwise-acquiring boards without even having
a need ahead of time and so it becomes easier to see trends,
that most boards did have the feature. Another way to go is
to find the board online, download the bios and open it up
with a bios editor, which will show the feature/setting if
present. How long that takes has a lot to do with how
proficient you are at Google searches, but generally far
less time than looking around in a single shop for a board
or misc electronic bits.