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how to power a hard disk

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bhan1992

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hi all,

A hard disk uses a connector with 4 pins (+12V GND GND +5V)
I tried to connect a AC/DC 12V 250 mA adapter to power the hard disk. I connect the 12V to the 12V pin of the hard disk and uses a 7805 to convert the 12V to 5V and connect to the 5V pin on the hard disk, it won't work.
Need your help a bit here. Could it be I don't have enough amp to power the hard disk? can i connect that 2 GND pin together?

Thank you for your reply in advance.
 

Did you check the current requirement of your disk, 250mA is very low , you 'll need more current.
The grounds should be connected and they are probably connected internally anyway.

I have a Seagate 3½ disk in fron of me and it cays 12v/0.35A and 5v/0.72A which means 1A total
 

ok then I think i know whats wrong now.
the hard disk states there 0.6A for the 5V and 0.3A for the 12V. I guess I have to get myself a 1A adapter.
if i were to power a circuit with a PIC and 10 LEDs. It is good that I get a 2A adapter right? I want to power both at the same time.
but will 2A overload the PIC?
thanks again
 

The 2A describe the max current that the adapter can provide, if your total current is lower than that then you are fine.

but will 2A overload the PIC?
Click to expand...
Having a 2A adapter doesn't mean that the pic will be forced to get 2A, it is just a max rating
 

ic. You mean the 2A on the adapter is the capability of the adapter to supply 2A to all the components. Just make sure the total current required by all the components in the circuit does not exceed the current rating on the adapter?
so it won't harm the PIC?
 

Yes , the rating is just the max current that the adapter can provide, no component is forced to get that current , you can have a pic that gets only a few mA from a 10A adapter , it doesn't matter.
 

ok thnx for the help man! appreciate that.
 

me curious if u made it ?

is it possible to use just one adapter to obtain both 5v and 12 volts ?
i have a 12volts regulated switch mode adapter.. and its current rating is 3.5 Amps so can i just use it somehow ? or i need a seperate 5v adapter for the 5v ?
 

1 adapter will be sufficient. u can get a 7805 to regulate a 5v line. then u just connect the 12v line and the 5v line to the hdd accordingly. hope it help
 

so u mean i connect 12 volts directly to hdd and also make this 12 volts as input to 7805 and connect the 7805 output to the 5 volts pins of hdd ? thanks
 

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