rotary switch

I need to find a 6 pole, 6 position rotary gang switch. I hope I have
described it correctly. It's for power distribution, 12v 5a max. I am
trying to make a hard drive selector, cheaper than the Trios selectors
on Ebay currently going for $60 and up. It's my understanding that a
computer BIOS will not detect a drive if it does not have power applied
to it. So I need to route +12v and +5v (and grounds)to 2 of 3 drives,
and jumper the slave pins on 1 of the 2 selected drives.
+12v +5v 12v gnd 5v gnd slave jumper
position 1 1&2 1&2 1&2 1&2 2
position 2 1&3 1&3 1&3 1&3 3
position 3 2&1 2&1 2&1 2&1 1
position 4 2&3 2&3 2&3 2&3 3
position 5 3&1 3&1 3&1 3&1 1
position 6 3&2 3&2 3&2 3&2 2
Any ideas where to buy just 1 or 2, reasonably priced?
Reply to
Steve Walker
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I don't understand why you need to switch the grounds. I'd think that without the power, a drive would be totally inert. I have a archive drive that I switch the 5 & 12v to and BIOS doesn't see it. Am I missing something? Mine is an IDE drive, FWIW.
Bob
Reply to
Bob Engelhardt
Why on earth do you want to do this? Rotary switches are noisy (electrically) and notorious for destroying keyboard ports, mouse ports and parallel ports on computers. You're asking to destroy your hard drives.
Reply to
Cydrome Leader
I just mounted an angle sheet metal plate on the outside of my side case.
Slotted it so it fits my hard drives, as well for cable pass through for mb.
I can change the hard drives by removing the cable, jumpers, etc.
I have also used those big fat tray things for hds. I no longer use them.
xman
Reply to
xmRadio
and notorious for destroying keyboard ports, mouse ports and parallel ports on computers. You're asking to destroy your hard drives.
Electrically noisy? The switch will only control voltage, not data, and will only be switched to different positions when the computer is off.
Reply to
Steve Walker
Then get yourself a couple of removable drive adaptors. These are intended for folks who want to lock drives containing sensitive data up in a safe overnight, but they would suit your purpose.
formatting link

Reply to
John Ings
If I had a need to switch between many hard drives, I would just by a set of removeable hard disk trays. About $AUS20 each at time. Plug in the drive I want, then power up.
The dead drives in the chain may affect the signal.
Reply to
Terry Collins
What he wants is this: http://208.34.209.68/411gb/411gb.htmMy best guess would be frys/outpost.com. Or partexpess.com is another that might have it.
-Nebruin
Reply to
Zipper
I've used the removable drive trays for years and love 'em. The only problem with them - and you'll have the same trouble with the rotary switch hookup you're considering - is that changing the drive from master to slave requires access to the back of the drive (meaning you have the tray out and opened and the drive unbolted) to move a jumper from one set of pins to another.
BTW, I don't know exactly what's in the Trios selectors but they are not just simple switches. On the machines I've used that have them, when you want to change the selected drive, you have to power down the machine and then wait maybe 10-15 seconds before pushing one of the Trios buttons. If the power supply isn't completely dead, there's the possibility that your selection won't be registered and the drive that runs won't be the one you think you selected. I didn't believe it until it happened to me.
Tove
Reply to
Tove Momerathsson
Looks neat, but hard to find. More messy but easy to find: put a four (N.O.) pole relay in the lines to each drive. Then any rotary switch to power just the relay coil.
Karl
Reply to
Karl Townsend
and notorious for destroying keyboard ports, mouse ports and parallel ports on computers. You're asking to destroy your hard drives.
Adding silly knobs that blow out your computer is a really bad idea.
Reply to
Cydrome Leader
NO NO NO NO NO NONO
if you really want to do this, just shut off the +5 and leave all other stuff alone
and your current for a drive is not as much as you say - and if you are switching with power off, you don't need 5 amp contacts. Get three 15 cent slide switches, one for each drive, turn ON the two you want on, and leave the other off. You can use a second set of three switches to switch the master/slave configureation of the drives as well (just short or open the slave pins)
bill n
Reply to
william_b_noble
What I would suggest is getting a wafer switch kit. You can set the number of positions (up to twelve), and stack up decks to handle what you want.
In reality -- especially since you won't be switching hot, I would like to make some suggestions:
1) Don't switch the ground pins. Leaving the grounds connected keeps the drive from pulling on the data leads while other drives are active, switching them leaves them floating, where other things can happen.
2) The wafer switch style, if limited to six positions, can handle two separate signals per deck. Use one deck (close to the panel mount) for switching the master/slave jumpers, and the other deck can switch the +5V and +12V power lines.
3) Buy the components a bit longer, and add a dummy deck of sheet aluminum between the jumper switching deck and the power switching deck. It will only need three holes -- two for the two bolts which hold the stack together, and a larger central one to clear the shaft.
I would expect that such switch components could be purchased from someplace like Mouser, Digi-Key, or one of the others like that.
If you get a full kit, it will have the components to make quite a few switches, and also the ability to build up a very complex set of switching functions -- such as having all the jumpers connected except for a single drive (assuming that these drives are the kind with a jumper present for either cable select or master, and no jumper if slave.
But -- of course -- you *could* stack six drives in a standard 50-pin scsi cable and talk to all of them at once -- certainly with any unix variant, at least. And with a fast-wide SCSI, you can talk to up to fifteen drives on a single cable with no need to switch them.
And put them in an old Sun MultiPack (one style for six 1.6" high drives or another for twelve 1" drives), all with the 80-pin SCA interface, and this makes the drives hot-swappable. Unmount the drive from the command line (at least in unix), pop the side off of the MultiPack, unplug the drive and plug in another -- while the computer is still running. I do this regularly, to swap out drives for newer bigger ones -- or sometimes for ones which still work -- one of the hazards of buying used drives. :-)
Enjoy, DoN.
Reply to
DoN. Nichols
Steve, This is a bad idea. You are just asking for trouble hooking that many drives on a single IDE cable, even if they are are powered down. The extra capacatiance of the longer cable and the 'unused' drives WILL affect the signal timing. One of the reasons that the devices like a Trios cost so much is that they and not just simple power switchs, but have circuitry to isolate the disconnected drives.
Honestly with 100GB drive so cheap now days I just spend a few bucks an get a BFD (Big Fricken Drive)
Dave
Reply to
Dave August
Don't run the drives dead on the cable line or you will have serious troubles accessing the drives that are active. Electronics in the drives do not like seeing negative signals at all. In additioin, the data cable also does have ground lines that will end up bouncing all over the place when you try to do this. The best solution is to use one of the docking bay systems which will allow for the switching of a drive when the computer is powered down without any problems.
-- Why isn't there an Ozone Hole at the NORTH Pole?
Reply to
Bob May
Or picking up an outboard scsi array.
Gunner
Lathe Dementia. Recognized as one of the major sub-strains of the all-consuming virus, Packratitis. Usual symptoms easily recognized and normally is contracted for life. Can be very contagious. michael
Reply to
Gunner
I've got one such device, Sun Microsystems, with 6 18GB drives. Haven't used it in a year but works fine... need it?
Reply to
Dave Hinz
Look at this approach:
Jordan
Steve Walker wrote:
Reply to
Jordan
The problem with BFD's is that sooner or later MS will screw your boot sector and you had better be skilled at re-installing it.
My 2c is that he wants to run different OS's.
Reply to
Terry Collins
I run multi-boot with several OS', including 'nix... ya can partition em ya know, and things like Ghost make fixing blown MBR's easy...
--.- Dave
Reply to
Dave August

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