Hoi!

I'm currently building my 8x slot-expander.
Thanks to the plenty infos and the detailed DIY-description of D. v. Oosten (published in MCM 37/38) things has gotten very easy

But there are still some unanswered questions...
The MSX standard defines +5V, +12V and -12V power supply for cartridges. I was wondering which modules uses that -12V line? In the DIY it's said that only few hardware uses +/- 12V.
As I only get +5V and +12V from a PC (HDD) power supply, would it have a negative impact to leave the -12V line? Or get it from my MSX, which -in the worst case- has to supply 8 modules w/ it's single -12V line w/ 50mA (50mA / 8 = 6.25mA per slot!)

Thanks in advance

-12 is used only on circuits that use operational amplifiers (sound cartridges?) and serial devices (which does not use MAX232-like devices, which needs only a +5V rail). I think you should do it complete - with the -12V. You never know when a out-of-spec cartridge or something bizarre will need the -12V rail.

Where is that DIY-Description you told about?
Greetings from Brazil!

The soundcartridge it regards most, moonsound ,msx -audio, fm-fpac etc.
A cartridge that needs -12v is inside the specs and not outside the specs alexandre !

I found the DIY docs on H. Ottens page. (he scanned and converted these docs to PDF).
Hans Otten's MSX DIYs

It's recommenced to (download & read all the descriptions, in order to understand it's functionality. But these docs are (mostly?) in dutch, so it'll be very difficult if you can't read dutch!
Or alternatively you just follow the scematics

Btw, I've mainly used this one: Slotexpander eerst begrijpen en dan nouwen (free translation: First understanding slotexpanders then building it )

So it isn't a good idea to leave out the -12V power line... (in fact, it'll be used for my sound expansions)
Well then have to figure out something, like an external power supply.

Thanks Alexandre & sunrise

Sunrise: You are right, I used the wrong word, someday I'll learn to speak english

Hope you will succceed in building the slot expander! And yes, -12V is absolutely required to adhere to the standard. Many cartridges such as audio and rs232/modems use it. With a slotexpander with this capacity it is inevatible to have an external powersupply. An old PC psu will do fine.

Quote:

I found the DIY docs on H. Ottens page. (he scanned and converted these docs to PDF)

I do not expect the mentioned url to change soon, but the preferred location is:

MSX Info pages

Hans

PS And yes, it would be nice to have some of these documents translated.