Amiga.org
Amiga computer related discussion => General chat about Amiga topics => Topic started by: orange on March 25, 2007, 07:01:58 PM
-
I'm looking for a good power supply (small, cheap, reliable) that can provide +5V only. I need it for external PC floppy drive that can draw up to 1A. I'd like to purchase one on ebay, but don't know the keywords. (is there some laptop, console.. anything that uses +5V only?)
PS. I'm sure the floppy doesn't use +12V
-
I'm pritty sure that you will need a 12v connection to drive some of the ICs.
-
You need 12+V and 5+V to run a floppy.
Just 5+V wont do it.
Mike.
-
Hi, why dont you just look for a cheap adjustable powersupply, they can
usually been adjusted between 5-12V and 1A current should not be a problem, their small and you should be able to find them in almoust any store.
-
If we need 5V and 12V then the cheap universal PSU wont do the the trick..
-
A while back, I bought a USB to IDE adapter for less than 20 bucks. It came with a power brick already wired for an HD or CD/DVD drive. It would just need an adapter to power a 3.5" floppy drive. If you could find one of those, you could use the power supply and set aside the USB part "for later".
If you really only need the 5V, you should be able to find a wall wart rated at 5Vdc. If not, get one at 9V. Rectify it to DC if you can only find an AC one. In either case, use a 7805 on a heatsink to regulate it to 5V.
Try this transformer (http://www.allelectronics.com/cgi-bin/item/DCTX-5200/790/5_VDC,_2000_MA_WALL_TRANSFORMER_.html)
-
I think most 3.5" drives will use only the +5V supply.
Wall adapters (DC) may have small smoothing capacitor, AC of course none?
With 7805 it's best to use ceramic capacitors on pins of the regulator, as is suggested by manufacturer's datasheet.
Heat sink is likely to be needed... Might burn fingers without?
-
The maximum a 7805 can regulate is 1A, so you really want a bigger version like the 78S05 (2A) or the 78H05 (5A, not so common). And yes, you should have a heatsink on it, along with a tantalum capacitor and a reasonably sized electrolytic capacitor for nice smoothing and regulation.
Alternatively you could look for a regulated 5v supply, but they're not as common as a cheap unregulated unit.
Remember, when you're looking at a power supply looking to supply 1A, it's best to go way over that, say 2A to give a nice margin of safety.
-
For what JimS said, I recommend something like these:
1)
http://eshop.macsales.com/item/Newer%20Technology/U2NVSPATA/
2)
http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=1871517&Sku=M501-1188&SRCCODE=NEXTAG&CMP=EMC-NEXTAG
Only one word of warning: I just fixed one of my adapters' PSU (this was a ByteCC product, which I don't recommend because I had troubles with the cables... and now the PSU). The capacitors leaked and I've used it sparingly. These "Made in China" PSU's are enclosed without any breathing space and they can get rather warm, so these capacitors leaked to death, bulged and all that. PSU failed one day. Anyways, now I've replaced them ($1.80 or so for 4 caps from Jameco), and made some holes in the unit so that it breathes. I assume all others are also without holes, so if you leave it on over-night etc, then it will fail sooner rather than later.
If you want to be more daring and experimental, there are many "mini" PSUs offered by Jameco (as well as other companies):
http://www.jameco.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&catalogId=10001&langId=-1&categoryId=4540
as well as:
http://www.google.com/pagead/iclk?sa=l&ai=BohNYxBKqRf6wJpzwQtPzzdgBzcDMBp2g27QCrfXoPuDrJQgAEAEYAVDQja-XBmC7vq6D0AqYAedzoAGLo7b_A8gBAYACAQ&adurl=http://www.mini-box.com/s.nl/c.ACCT127230/sc.8/category.13/.f
Good luck and I believe you do indeed the 12Volts.
-
thanks all, I'm still pretty sure its only +5V, its NEC FDD and I've opened it and checked PCB traces. (Unless its multilayered PCB, nothing is connected to +12V pin.)
I have found this (http://cgi.ebay.com/FOR-HARD-DISK-DRIVE-12V-5V-AC-Adapter-Power-Supply_W0QQitemZ150105244800QQcategoryZ64471QQrdZ1QQcmdZViewItem)
cheap thingy on ebay. It looks very interesting and its very very cheap. Wonder if it could be used to power some Amigas, too?
-
To power the actual machine, I don't think so. Most of those don't have enough power coming out of them. But to power HDDs and floppies, yeah, I don't see why not. It looks almost identical to the ByteCC one I've got. So just make sure you poke somem holes in it :-)