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Author Topic: -8, -7 volt line from PSU  (Read 3239 times)

endscape

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-8, -7 volt line from PSU
« on: September 25, 2003, 10:09:16 PM »

Hello all-

I just bought a big n' wonderful 240 x 128 LCD that I'm hooking up to run Liquid MP3.  The schematics I've found to wire it to a parallel port are a tad bit conflicting.  One that I've found says to ground a certain pin, while the other wiring diagram says I need a -8 or -7 volt line.  

Anyone know how to create the -8/-7 volt line from a normal computer PSU?

Any help would be greatly appretciated,


Endscape
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Merlinicorpus: "Ok, before we go any further, let me enlighten you on something. Z is not an S. Accordingly, you should not use Z in place of an S. Words like "thanks" are not something that should be abriviated. It's just as easy to type KS instead of X. When using exclamation points, either use one or three. If you are using so many that you can't keep the shift down and start adding 1s, you have probably added a few dozen too many."

viridius

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-8, -7 volt line from PSU
« Reply #1 on: September 25, 2003, 10:17:32 PM »

While there is no -7 volt line from the PSU, you could always get a -7 volt regulator and hook it on to the -12 volt line.
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daPyr0x

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-8, -7 volt line from PSU
« Reply #2 on: September 25, 2003, 10:44:32 PM »

vir; couldn't you just use 12v as VCC and use 5v as gnd?
or wait, -7?
yeah
+5v as gnd, -12v as vcc.
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PIYIRIO

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-8, -7 volt line from PSU
« Reply #3 on: September 25, 2003, 10:54:17 PM »

um... you'd have to use the -12 as the postivive and -5 as a ground for -7 volts, -12 and +5 would give you 17 and fry your -7volt stuff. they're all on the atx mobo connector. i don't know what wire is what now though so you gotta google.
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Skylined

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-8, -7 volt line from PSU
« Reply #4 on: September 25, 2003, 10:58:25 PM »

Messing with mobo connectors isn't a good idea.
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endscape

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-8, -7 volt line from PSU
« Reply #5 on: September 25, 2003, 11:03:26 PM »

well actually in this case I could, since I'm going to have a second ATX PSU running the LCD (and some fans and what not)


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Merlinicorpus: "Ok, before we go any further, let me enlighten you on something. Z is not an S. Accordingly, you should not use Z in place of an S. Words like "thanks" are not something that should be abriviated. It's just as easy to type KS instead of X. When using exclamation points, either use one or three. If you are using so many that you can't keep the shift down and start adding 1s, you have probably added a few dozen too many."

viridius

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-8, -7 volt line from PSU
« Reply #6 on: September 25, 2003, 11:36:38 PM »

Since the rest of the circuit will have voltages relative to true ground (zero volts), the -7 portion of the circuit must be at an actual -7 volts.
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endscape

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-8, -7 volt line from PSU
« Reply #7 on: September 26, 2003, 12:59:03 AM »

Quote from: viridius
Since the rest of the circuit will have voltages relative to true ground (zero volts), the -7 portion of the circuit must be at an actual -7 volts.


I may just be illiterate, but I dont completly understand that.  Could someone explain it a little more, or point me in the right direction?


Thanks,


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Merlinicorpus: "Ok, before we go any further, let me enlighten you on something. Z is not an S. Accordingly, you should not use Z in place of an S. Words like "thanks" are not something that should be abriviated. It's just as easy to type KS instead of X. When using exclamation points, either use one or three. If you are using so many that you can't keep the shift down and start adding 1s, you have probably added a few dozen too many."

Skylined

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-8, -7 volt line from PSU
« Reply #8 on: September 26, 2003, 01:52:47 AM »

Ground is always a reference.
So the -7V has to be a real value.
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endscape

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-8, -7 volt line from PSU
« Reply #9 on: September 26, 2003, 02:09:11 AM »

AHHHH, I thought that's what he meant, but wasn't sure, thanks.


Any more thoughts on getting -7 volts from an ATX PSU?
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Merlinicorpus: "Ok, before we go any further, let me enlighten you on something. Z is not an S. Accordingly, you should not use Z in place of an S. Words like "thanks" are not something that should be abriviated. It's just as easy to type KS instead of X. When using exclamation points, either use one or three. If you are using so many that you can't keep the shift down and start adding 1s, you have probably added a few dozen too many."
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