how to get 3.3v for pson signal? also inverted signal?(expert question)
ok, another question, this one is harder
I have a small form factor motherboard (it's already got a 2.4G P4 with 1gb memory)
it's made by compaq which is a problem because they use non-standard power supplies :( grrr...
I've spent days googling this and so far I've found that it will need a 3.3 PSON for a signal to power up the mother board.
interestingly someone online had made a device for this
when he rigged up a way to use the mobo with a standard ATX power supply (he's got some pretty ingenious electronic hacks on his website)
He uses 2 resistors (plus some other parts) to bring the 5v signal down to 3.3v.
I understand what the 2 resistors do, but why are the other parts needed? (see his diagram)
Can't i just get away with the 2 resistors to trim the voltage down to 3.31v? Or is the power still not close enough to 3.3?
so when trying to set this up, there are 2 problems that need to be resolved:
- 3.3v standby voltage
- inverted PSON signal
also I don't fully understand what an "inverted PSON signal" is.
also I noticed this comment:
"There's the option of hardwiring the PSON (perhaps to a switch, which would essentially be like an old AT psu functionality-wise, with the added trouble of having to switch the mobo on/off separately) , but that's highly inconvenient"
Why wouldn't this be a good thing? aside from having 2 switches?
on a side not if anyone ever needs the specs for the compaq psu/mobo check this page