Battery powered A1200

[motorollin]

Now I've got the A1200 that's never "bin" opened, I'm thinking of making it a portable games machine. I'm going to remove the floppy drive (I assume it'll still boot without it?), and put in an IDE flash card reader instead of a hard drive, and add a RAM expansion. I then want to power the whole thing from a battery so I can make it truly portable.

I'm aware the A1200 has a 5v, 12v and -12v supply. So my first thought is to get a 12v battery and split the 12v supply 3 ways. One would supply the 12v, one would supply 5v via a transformer, and the other well I don't know, how do you make +12v in to -12v?! I would have thought I would need to transform 220v to 12v and rectify to a negative voltage? Or can I "convert" +12v to -12v?

Also, how much current would a system like this draw? Is it realistic to power it from a battery?

Sorry for all the questions. I'm excited :-)

--
moto

[CatHerder]

It will definitely boot without it. I used to have an A500 with a HD in the floppy spot (adIDE) and only used an external floppy if/when I needed one. I used it as a BBS machine when I went to university after I sold off my 3000T and 4000 to buy a PC and some furniture (and a bag of weed and a case of beer if I remember correctly) and I think I used a floppy drive with it two or three times in a year or more.

Well, based on how much juice an A500 uses from a battery backup unit, I'd guess 20 minutes with a large laptop battery pack. Amigas are everything but power efficient. :-)

[motorollin]

Ok, I'll give the battery a miss :-) I'm going to remove the power supply from my XBox as it is fairly long and narrow, and not very tall, and see if I can cram it in to the A1200  :-D

--
moto

[hppacito]

Get yourself one of those converters that output normal ATX voltages out of 12 VDC. They are just a board with an ATX connector, usually used with ITX mobos. That will save you lots of troubles, and they cost around 15 Euro, IIRC.
If you DIY, get some TL494 to convert from 12 to 5, some transistors, a LM555 to ger -12 from +12 (as oscillator, later a diode and a couple of elkos).
Don't trust the stability of those 12 V from the battery... use another 494 from 12-> real 12V ;-)

There are some canned DC-DC converters from National and Texas... really nice stuff, they even give samles for free !

[bloodline]

motorollin wrote:
Now I've got the A1200 that's never "bin" opened, I'm thinking of making it a portable games machine. I'm going to remove the floppy drive (I assume it'll still boot without it?), and put in an IDE flash card reader instead of a hard drive, and add a RAM expansion. I then want to power the whole thing from a battery so I can make it truly portable.

I'm aware the A1200 has a 5v, 12v and -12v supply. So my first thought is to get a 12v battery and split the 12v supply 3 ways. One would supply the 12v, one would supply 5v via a transformer, and the other well I don't know, how do you make +12v in to -12v?! I would have thought I would need to transform 220v to 12v and rectify to a negative voltage? Or can I "convert" +12v to -12v?

Also, how much current would a system like this draw? Is it realistic to power it from a battery?

Sorry for all the questions. I'm excited :-)

--
moto

Getting the 12v down to 5v efficiently is a lot of trouble... just a buy a DC-DC converter from a good PSU site (I bought one from www.mini-itx.com), that will take a 12V supply and out put a standard ATX supply (which which you can take the required power lines).

But you would probably need a nice big lead acid accumulator (read: car battery) to get any length of play... (unless you want to mess around with expensive Li-ION batteries and over charge protection circuits).

-Edit- Gah, everone else beat me to it :roll:

[motorollin]

I've tried to find one of those 12v -> ATX converters, but I can't find one on the site you mentioned. Could you sort me out with a link?  ;-)

--
moto

--EDIT
I think I've found them. Any of these look any good?

--EDIT
Actually, this is a better link.

[hppacito]

This one WPPS55 looks just ok. Input 12 V, output up to 60W.
70% efficiecy... take that also in account ;-)

[motorollin]

Would 60W be enough for an A1200 with a RAM expansion and an IDE compact flash device, with the floppy removed? Also, any thoughts as to battery life if I powered this off a 12v battery?

Thanks as always for your help guys :-)

--
moto

[adonay]

60 watts would do just fine and you are saying you might use a CF card as well they dont draw much power.

Adonay :-D

[motorollin]

Wicked :-) I guess I can calculate the time I will get from the battery based on the current drawn by the ATX converter and the number of amp hours of the battery?!  :crazy:

--
moto

[adonay]

i had a plan just like this one. Only no batery involved mine was a A600 with internal PSU powerd by the adapters you get with something like this the powersuply would be easy to fit in the amiga and the cable wirering would be done trugh the floppy connector.The new HDs take upp to 40watt power so i think it would be good for powerering.

Adonay :-D

[leofoe]

How do you plan to powersupply the monitor? Or will it be a music-player only?

[boing]

I'm assuming you're removing the floppy drive when going portable.  I know you're removing the HD.  IIRC, the rest of the Amiga will work fine without the -12v.  In fact I'm not even sure it will need the +12 with the HD removed.  The CF card should run on 3v or 5v IIRC.  The only sticking point would be the voltage conversion through the IDE-CF adapter.  It wil be expecting to see a +12 and -12v iirc.  Bypass that though and you should be good to go.

I think this is your best bet.  If you don't need the -12v, no point in hassling over it.

Buy.com and others have big sales on rechargeable batteries this holiday season.  Charchers too.  Some take 12-20 batteries at the same time. Start your shopping here:

Recharge lots of batteries at the same time

Who knows what "super quick" charging means from SONY?

Where I find my deals for electronics like batteries

[Doppie1200]

Keep that idea of the battery powered amiga warm!

When the minimiga core will be functional someone might cram it into a coolrunner fpga and a less power consumptive amiga can be created.

[rustednail]

Hope this subject is still warm!

I believe some lap-top batteries might have all the voltages needed to run an amiga.  Seems like lap-top batteries have several pins out and I would guess its different voltages for verious parts of the laptop, but it has been quite some time since I have looked at any lap-top battery specs.

Could a old lap top display be used on an amiga?  I have an old lap top here, a 486 machine thats has a cracked case and wasnt worth much on e-bay.  I might pop it open and see what the vid connector to the display looks like

Did Pawls do that already?

-Bri