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PCI bus

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hodamoodi

New Member
i want to connect a card to pci bus just to use +12,-12,0&+5 v power
lines of it
now i want to know if i need to change any settings for the bus or its
enough to connect the board to the bus
and also what should i do to protect my pc from damages may be happens
after connnecting the card like overcurrent or etc
thanks
 

Nigel Goodwin

Super Moderator
Most Helpful Member
hodamoodi said:
i want to connect a card to pci bus just to use +12,-12,0&+5 v power
lines of it
now i want to know if i need to change any settings for the bus or its
enough to connect the board to the bus
and also what should i do to protect my pc from damages may be happens
after connnecting the card like overcurrent or etc
thanks
This sounds a REALLY silly idea, there are handfuls of connectors from the PSU carrying those voltages, use a spare one of those!.
 

justDIY

Active Member
all except the -12v that is ... pretty sure the ATX connector is the only place you'll find the negative refrence rails.

you're better off getting one of those compression splice fittings and tapping into the atx than messing with a high speed data bus, just for power.
 
Code:
                    Rear of Computer
                    :------:------:
               -12V |- B1     A1 -| Test Reset
         Test Clock |- B2     A2 -| +12V
             Ground |- B3     A3 -| Test Mode Select
   Test Data Output |- B4     A4 -| Test Data Input
                +5V |- B5     A5 -| +5V
                +5V |- B6     A6 -| Interrupt A
        Interrupt B |- B7     A7 -| Interrupt C
        Interrupt D |- B8     A8 -| +5V
            PRSNT1# |- B9     A9 -| Reserved
           Reserved |- B10   A10 -| +V I/O
            PRSNT2# |- B11   A11 -| Reserved
                    :------:------:
                    :------:------:
           Reserved |- B14   A14 -| Reserved
             Ground |- B15   A15 -| Reset
              Clock |- B16   A16 -| +V I/O
             Ground |- B17   A17 -| Grant
            Request |- B18   A18 -| Ground
             +V I/O |- B19   A19 -| Reserved
         Address 31 |- B20   A20 -| Address 30
         Address 29 |- B21   A21 -| +3.3V
             Ground |- B22   A22 -| Address 28
         Address 27 |- B23   A23 -| Address 26
         Address 25 |- B24   A24 -| Ground
              +3.3V |- B25   A25 -| Address 24
             C/BE 3 |- B26   A26 -| Init Device Select
         Address 23 |- B27   A27 -| +3.3V
             Ground |- B28   A28 -| Address 22
         Address 21 |- B29   A29 -| Address 20
         Address 19 |- B30   A30 -| Ground
              +3.3V |- B31   A31 -| Address 18
         Address 17 |- B32   A32 -| Address 16
             C/BE 2 |- B33   A33 -| +3.3V
             Ground |- B34   A34 -| Cycle Frame
    Initiator Ready |- B35   A35 -| Ground
              +3.3V |- B36   A36 -| Target Ready
      Device Select |- B37   A37 -| Ground
             Ground |- B38   A38 -| Stop
               Lock |- B39   A39 -| +3.3V
       Parity Error |- B40   A40 -| Snoop Done
              +3.3V |- B41   A41 -| Snoop Backoff
       System Error |- B42   A42 -| Ground
              +3.3V |- B43   A43 -| PAR
             C/BE 1 |- B44   A44 -| Address 15
         Address 14 |- B45   A45 -| +3.3V
             Ground |- B46   A46 -| Address 13
         Address 12 |- B47   A47 -| Address 11
         Address 10 |- B48   A48 -| Ground
             Ground |- B49   A49 -| Address 9
                    :------:------:
                    :------:------:
          Address 8 |- B52   A52 -| C/BE 0
          Address 7 |- B53   A53 -| +3.3V
              +3.3V |- B54   A54 -| Address 6
          Address 5 |- B55   A55 -| Address 4
          Address 3 |- B56   A56 -| Ground
             Ground |- B57   A57 -| Address 2
          Address 1 |- B58   A58 -| Address 0
             +5 I/O |- B59   A59 -| +V I/O
 Acknowledge 64-bit |- B60   A60 -| Request 64-bit
                +5V |- B61   A61 -| +5V
                +5V |- B62   A62 -| +5V
                    :------:------:
                    :------:------:
           Reserved |- B63   A63 -| Ground
             Ground |- B64   A64 -| C/BE 7
             C/BE 6 |- B65   A65 -| C/BE 5
             C/BE 4 |- B66   A66 -| +V I/O
             Ground |- B67   A67 -| Parity 64-bit
         Address 63 |- B68   A68 -| Address 62
          Address 61|- B69   A69 -| Ground
             +V I/O |- B70   A70 -| Address 60
         Address 59 |- B71   A71 -| Address 58
         Address 57 |- B72   A72 -| Ground
             Ground |- B73   A73 -| Address 56
         Address 55 |- B74   A74 -| Address 54
         Address 53 |- B75   A75 -| +V I/O
             Ground |- B76   A76 -| Address 52
         Address 51 |- B77   A77 -| Address 50
         Address 49 |- B78   A78 -| Ground
             +V I/O |- B79   A79 -| Address 48
         Address 47 |- B80   A80 -| Address 46
         Address 45 |- B81   A81 -| Ground
             Ground |- B82   A82 -| Address 44
         Address 43 |- B83   A83 -| Address 42
         Address 41 |- B84   A84 -| +V I/O
             Ground |- B85   A85 -| Address 40
         Address 39 |- B86   A86 -| Address 38
         Address 37 |- B87   A87 -| Ground
             +V I/O |- B88   A88 -| Address 36
         Address 35 |- B89   A89 -| Address 34
         Address 33 |- B90   A90 -| Ground
             Ground |- B91   A91 -| Address 32
           Reserved |- B92   A92 -| Reserved
           Reserved |- B93   A93 -| Ground
             Ground |- B94   A94 -| Reserved
                    :------:------:
Quick search on pinouts.ru. You're welcome.
 

Styx

Active Member
What exactly are you trying to do?
TRACO (and Newport) make DC:DC converter that output +/-12V DC and a MC05 reg will give you yr 5V line, UNLESS you are making a PC-card I would stear clear of the PCI bus
 

hodamoodi

New Member
thanks evrybody
but i'm using pc power because my card use pc serial port and i thought it would be more compact on this way
anyway,don't matter which port i get power , what should i do not to make any harms for the pc ?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
hodamoodi said:
thanks evrybody
but i'm using pc power because my card use pc serial port and i thought it would be more compact on this way
anyway,don't matter which port i get power , what should i do not to make any harms for the pc ?
You still don't make it clear what you're trying to do?, obviously if you're building a PCI card (which is fraught with difficulties!) you would take power from the PCI bus (as long as it's not too much). But if you're connecting externally via a serial port it would be really stupid to take power from there, take it from the PSU instead.
 

hodamoodi

New Member
from PSU u mean Power supply unit?
i need -12 so I must use the power supply 20 pin connector
it is connected and i cant use it the other 4 connectors do not have -12
so what should i do?
i'm not using pci data pins, but i want to have my card connected inside pc to avoid using another big Power supply outside PC,
 

hjames

New Member
I'd agree that trying to pull power from a PCI connector is a bad idea - if you want to do it properly, the best thing to do is to find a PCI extender card (Digikey/mouser carry them, most places that sell computer server parts also carry them, expect to pay US$10-40), and hack it up. Then be sure to fuse any power supply pins, and possibly put a diode to prevent backfeeding power. Note that if you accidentally short any of the power rails to another, you're likely to *TOAST* the entire computer instantly.

If you can state your objective, then there's a good chance someone can suggest a better answer - for example, if you just need a quick and dirty -12V supply voltage at few mA, a 555 oscillator, a diode, and a capacitor are all you need. A more robust switching power supply will cost you US$5-10, be smaller, and less risky than tapping the PCI connector.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
hodamoodi said:
thx, but whould u tell me how to build a dirty -12v with 555?:confused:
How can we?, you've never told us yet what you're trying to do? - so we don't have any idea what your requirements are - or even if you really require -12V?.
 

justDIY

Active Member
Nigel Goodwin said:
How can we?, you've never told us yet what you're trying to do? - so we don't have any idea what your requirements are - or even if you really require -12V?.
obvisouly it's a super-secret classified project ... he could tell us, but then he'd have to kill us! ... although usually, super-secret projects are well funded and have entire departments full of phd level engineers for these kinda problems.
 

hodamoodi

New Member
dear experts
thanks a lot to help me so much, but i really cannot get the hint
i have a transducer which need 8,0,-8v to work
i want to get its tiny outputs,amplyfy
with opamps(LM324) and send it PC serial port by a micro to see the output
so easy, the only thing i want is to be able to put this inside the pc case

no secret,no killing,...

i made the cuircuit u sent me for -12 with 555,but it give me -9 it's hardly enough to convert 8 to -8
and the current is not enough to run anouther regulator
so why my idea about using pci power is silly?!!!!!!!!!!
what is the problem?
my board consist of 2 lm324,an avr micro,a max232,a 7808 regulator & that's all(just some resistor and capasitors)
i do not need so much curent to be so harmful
still using pci is silly?
and about fuses do i eally need fuse they are so big 4 my little board
is't there any other way?to keep safty?
and if using fuses how much they should be? 0.5A is ok 4 motherboard?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
hodamoodi said:
dear experts
thanks a lot to help me so much, but i really cannot get the hint
i have a transducer which need 8,0,-8v to work
i want to get its tiny outputs,amplyfy
with opamps(LM324) and send it PC serial port by a micro to see the output
so easy, the only thing i want is to be able to put this inside the pc case
Well at least we're getting a little more information, but it's still rather sparse?. For example, what is the transducer?, and what are it's current requirements?, and what are the current requirements of the complete device?. Presumably you have it built?, running off external supplies?, and can measure it?.

i made the cuircuit u sent me for -12 with 555,but it give me -9 it's hardly enough to convert 8 to -8
and the current is not enough to run anouther regulator
That's because you didn't give enough information!.

so why my idea about using pci power is silly?!!!!!!!!!!
Because a PCI socket is a fairly fragile thing, both mechanically and electrically, there's too much scope for destroying the motherboard.
 

hodamoodi

New Member
OK!
but despite all u said,i connected my board without any fuse or similar things to pci bus
nothing happend
it worked propperly
just yet i don't know what to do about safty

the transducer is an old blood pressure transducer made by harvard,
about cuurents:
transducer get 4 mA from each of 8v and -8v supplys
and the cuircuit without transducer get
2mA from -12,7mA from +12 , 10mA from 0 and 5mA from +5
all are below 10mA and the sum is below 100mA
so...!
 

Nigel Goodwin

Super Moderator
Most Helpful Member
hodamoodi said:
OK!
but despite all u said,i connected my board without any fuse or similar things to pci bus
nothing happend
it worked propperly
Nothing will happen, UNTIL something goes wrong! - it's a VERY poor design choice!.
 

freeskier89

New Member
Not to mention the PCI card boards that I have seen that will go in the socket are 30+ times more expensive than a molex connector :D
 
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