exxos's Atari, Amiga & retro forum

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

Is something like this suitable?

https://www.amazon.co.uk/Module1-25V-Positive-Negative-Regulator-Adjustable/dp/B07MLS4MV4

Cheers

Assume so. Why does stuff need -12 anyway ?

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 ...

Ok cool thx

@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

... 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.

Steve wrote: 09 Feb 2022 17:55 @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.

@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?

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.