i asked a couple of people this in the IRC channel, but just wanted to make sure it's all right. pretty much i don't have room for a removable hd tray, but i'd like to be able to turn off the hd so people can mess with my computer (at lans, etc.). so would this work? (see pic). only thing i'm not sure about is crossing the two ground wires. also, someone said i should maybe throw in a few diodes in case of a lil power surge? anyways, here's the pic... *EDIT* pic is b0rk3n - now in next post...
The grounds to a power supply are all the same so you can cross them if you want - there wouldn't be any damage. As for the HD power, I can't see the pic but I'm assuming you are just installing a switch in series with the power of the HD. I wouldn't actually advocate doing such a thing since you could corrupt your hardrive if it was doing some work by cutting power from it without any warning to the system or software itself. Hope that helps somewhat, sorry if I misunderstood you.
hrmm.. uploadit.org is down atm. anyways, yeah - it's a spst keyswitch hooked up to the two ground wires crossed together. as for cutting power, i'd only turn the switch when the pc is off but one other thing i might do to expand this is make the keyswitch dpdt and have TWO hds hooked up - one for linux, one for windows. would there be any problems if one HD is receiving power and the other has the ground cut? (i'm thinking no, but i don't want to have to replace two HDs for a stupid mistake ) *EDIT* put pic on a new host. here ya go!
I have tried something similar, and found that the drive would ground through the casing into the case, so the switch would have no effect However using a double throw switch would work on the 5 & 12volt lines. Dont know if theyd like it if you turned the system on with the drive power off though.....
well, the thing is that i can't figure out how da **** those removable hd trays work. my brother's pc has one and even if the tray is pushed in all the way, the HD doesnt power up unless the keyswitch has been turned to the "ON" position and i remember i looked at it, and it's a spst keyswitch, so i can't figure out what's getting turned on/off with the switch (and i can't look at his cause he's away at college)... Don't try to get round the swear filter... cpemma
Ive never used one of those removable trays, but i imagine it would insulate the drive from the casing and so your circuit would work.
Oh okay, that solves most of the gray areas. I think you could either insulate the drive, like what the above poster says, and do it that way or have a DT switch where there is a 5v feed in and a 12v feed in so you will cut off total power from the drive. If you do decide to cut the ground, make sure it is both of the black wires and not just one. As for the linux/windows, that would work, set both of them on "Master" via jumpers and turn one off and the other one on when you want to switch. Good luck, eager to see it.
I made the exact same thing for a friend of mine. DPDT switch, one hdd for win other for linux. However it ran into troubles, he reported that the powered hdd would make "clunking noises"...I have no idea what that means. The only thing I can think of is that the switch wasn't able to handle the large amounts of current the HDD was drawing, which was probably exaghurated by my poor soldering You can have a go and prove me wrong, but I would personally use the jumpers and connect them up to a switch.
I hope you know that if you have the PC on while you switch the HDD off Windows willl die. And the HDD wont like you because it is not designed to hotswap
yeah, i know - i'm not retarded - that's like pullin the plug while your pc is on. the only problem with the jumpers mod is that i want to have a keyswitch, and i can't find a dpdt one.
I believe the spst switch on the hd racks is connected to a relay or maybe a couple relays. This might look a little odd, but why not get 4 switches (one for each wire) and attach the levers together and make it one big switch?
I dable with electronics a bit so here is my opinion First the switch should not control the actual hd wires but a relay switch. I say use a relay switch because a relay can switch 2 seperate wires at the same time. and the key switch would just power the relay on and off. Btw the relay shuld be set when power is not going through it it should let the hd work but when you turn the relay on you disconect the hd so this way you reduce the energy being used in the relay. Hope this helps. Oh btw radioshack has relays that are made to work with 12v or 5 v for about 3bux or so. SO the whole mod should not cost you more than 10 bux in total. just my two cent. Here is my sketch http://server4.uploadit.org/files2/101203-relayswitchsetup.JPG
i could have been positive that the grounds were in fact different, that is why you can do the 12v to 7v mod with fans using a 5v ground wire, instead of the 12v ground wire....
7v are in fact betweent +12v and +5v...it has nothing to do with ground wires. the ground wires in the pc are all the same they are more for increased current draws the safest way would be through a relay and cut the 2 possitive leads in your case if you can't find a switch to do it directly
jaguarking11, that schematic looks good, but it would only work for cutting off just one hard drive, right? so how could i use it to switch between TWO hds? (i may just not understand everything - i'm not the best electronics wizard, ya know )
Someone mentioned a relay, but how about a transistor? Since a transistor could probably handle the higher currents that are switch can't (if thats what was the problem in my design). I wouldn't really know how to wire this method up, but I'm sure someone could help. I also coudln't find a DPDT keyswitch, but I suppose you could use 2 SPST's for the 12V and 5V lines? Or, you could use something like this: Missile Switch Protective Cover Its a cover for the switch, just makes it harder to accidently flick it while the comp is running. I only know of this store (in Australia) which sells it tho.
make the switch power up the relay, that way wou would have a dpdt switch with only a spst one(if those are the correct names)
found one! that should work, right? (hook 12v up to one line, then 5v up to the other). i don't particularly like the squarish look, but i can live with it (it's also removable in the "off" position, which helps me with my security issue too )
That just screams FLIP ME and would make it worse. For safety I would suggest using a relay with the switch set up so that when the power is on you can't flip the hdd's off. I'll make and post a schematic later.
