Is there -12v conversion on H5?

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Steve
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Is there -12v conversion on H5?

Post by Steve »

Maybe a silly question, but I need -12v for a Vofa. If there isn't a converter could someone please advise the easiest method for me to build my own little converter? Thank you
Steve
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Re: Is there -12v conversion on H5?

Post by Steve »

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exxos
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Re: Is there -12v conversion on H5?

Post by exxos »

Assume so. Why does stuff need -12 anyway ?
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frank.lukas
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Re: Is there -12v conversion on H5?

Post by frank.lukas »

some Graphiccards need only +5V but some also +12V and some need -12V too. On a original ST you can use the -12V for the serial port or maybe a max232 ...
Steve
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Re: Is there -12v conversion on H5?

Post by Steve »

Ok cool thx
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Re: Is there -12v conversion on H5?

Post by Steve »

@exxos Chris as you know I struggle to read data-sheets, I am wondering if putting +12v into the LM337 is the most efficient way to have it output -12v? (of course the device has an adjuster, I just want to know the most efficient input voltage)

Thank you,

https://www.ti.com/lit/ds/snvs778e/snvs ... 4390299097
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frank.lukas
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Re: Is there -12v conversion on H5?

Post by frank.lukas »

... on the Panther/2 slot pcb is a MAX232 (feed from +5V) from which the +12V and the -12V are taken for the graphics card.
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Re: Is there -12v conversion on H5?

Post by exxos »

Steve wrote: Wed Feb 09, 2022 5:55 pm @exxos Chris as you know I struggle to read data-sheets, I am wondering if putting +12v into the LM337 is the most efficient way to have it output -12v? (of course the device has an adjuster, I just want to know the most efficient input voltage)
You can't... It's a negative regulator not a voltage generator .. Depending on how much current you want, switched capacitor converters might be a simple solution. But there be modules from China doing this kinda stuff anyway.
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Re: Is there -12v conversion on H5?

Post by Steve »

@exxos Sorry I thought earlier on you said you assumed that device would work for me (I've bought it and am testing it now) So this won't convert positive to a negative 12 for me then?
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Re: Is there -12v conversion on H5?

Post by exxos »

Oh sorry thought that modules was the converter but that's a regulator board now I look closer. I would just look on aliexpress for converter modules.

Or look at the STFM circuit as it has one.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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