My new external hard drive!


I have an external hard drive I use for periodic backups of a particular computer.... or at least, I had an external hard drive. It was one of those USB bus powered 2.5" IDE things - nice and portable but not the first one I've seen fail (and it's not the disk itself that's gone but something on the IDE to USB board).

As portability wasn't terribly important for this role, I thought I'd save my employer, the NHS, about fifty quid of tax payers money by making myself a replacement out of scrap and spare parts (on my own time).

I already had a high capacity drive, a Seagate 160GB IDE unit although it was of the larger 3.5" variety. This wasn't a problem though as I don't need to carry it around much, for the most part it's going to sit in one place. For the caddy and electronics I pulled an old external CD drive off the store room shelf. This was about to be disposed of (following all WEEE guidelines of course), so the timing was perfect. It was made by Freecom and has a 2001 date printed on it's internal PCB so it was surprising to find it had a USB2 chipset as most devices at that time still used USB1.1 (including my own external CD writer purchased at around the same time for a shocking £150 as I recall!)

I opened the Freecom casing and removed the CD unit itself. This left me with the case, IDE to USB circuit board and IDE cable. I then simply bolted the hard drive in the space where the CD drive had been and hooked it up to the power and IDE cabling.

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Now, that would have been enough to get me running as it was all functional at this point, but the night was young and I wasn't happy with the gap at the front of the casing where the CD ROM fascia had once been....

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...So I took a trip into the attic and dug out my old box of computer case blanks from the days when I used to assemble computers to order. The curved blank plate shown in the picture above was a pretty good fit and formed a nice fascia that covered the ugly hole.

I still wasn't happy though. There were no lights on this thing - nothing to indicate power or hard drive activity. Fortunately I found just the thing in my box of junk bits...

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The little circuit board pictured was probably pulled off an old computer or scanner years ago. As you can see, it has a yellow and a green LED with each connected to a cable via a 150 Ohm resistor. I could have mounted the LEDs directly on the fascia by drilling two holes but I decided instead to mount them behind a clear plastic lens with the lens affixed directly to two holes behind the fascia. There were a few reasons for this...

The resistors next to each LED prevented easy mounting directly to the fascia but didn't get in the way of the lens;
The outside look is more attractive using the lens as it looks like two clear plastic windows instead of two protruding, differently coloured LEDs;
The light, when shining through the lens, looks more pleasing and appears with more 'depth'.

The lens itself was off a broken Dell keyboard that was also being scrapped. The Num Lock, Caps Lock and Scroll lock lights from the keyboard used to sit behind it! To use it in this project, I cut it into three pieces, using just two of them, as the spacing of the LED mountings of the lens didn't match the spacing of the LED's on the circuit board.

Hooking up the LED wiring is pretty simple. The power LED (green) is connected to the 5V line going to the hard disk (through the 150 Ohm resistor of course). The yellow LED is to indicate hard drive activity so the anode is connected to the 5V line via it's 150 Ohm resistor, while the LED cathode is connected to pin 39 of the IDE bus. Pin 39 is the 'activity' line and is there specifically to drive a LED. The activity circuit is shown below.

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So here we are, holes drilled in the fascia, lens and LEDs hot-glued into place and wired in...

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... and then sealed up ready for use...

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The final touch was to add one of my old badges from my PC building days!

Okay, so it's certainly big and clunky - but it works a treat and was built without having to shell out for any extra parts.