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Photo Geekery – What To Do With a Dead DVD Drive

A few months back, I saw an article about adding macro capability to cell phone cameras.  I asked Jay, our IT know-it-all if we had any dead drives.  Last week, I got my greedy hands on one and while working on a support case with Elaine, I took it apart and pulled the lens:

cameralens In the drive I took apart, there were two sets of optics.  I tried both and took the larger of the two, which worked better with my cell phone.  This lens has convenient ears that can be used for holding it into the camera with tape, but I just used my fingernail.

Here is a shot of the DVD drive’s front panel circuit board using the unmodded camera (click for full image):

IMAGE_112 It’s OK.  Not great – the camera has a special '”close up” setting and this is about as close as I could get it and stay marginally in focus.

This is shot with the DVD lens over the camera lens:

IMAGE_113 I can now get that chip very clearly in focus.  According to the spec of that chip, the long edge of the chip is a minimum of 4.9mm and a max of 5.0mm.  This means that the field of view in the close-up shot is approximately 18mm x 12.5mm.  In the non-macro shot, the chip appears roughly 1/4 the size, making the field of view 72mm x 50mm.  So the lens adds a nice, cheap 4x for close up work.

But there is a part two to this and a reason why I took a shot of this particular chip on the DVD front panel UI board.  This chip is a stereo headphone amplifier that runs from 3V to 6V (ideally at 5).  Being able to read the chip ID, let me find the data sheet which tells me what the pins are.  If I hack the board down (a la this instructable), solder in a battery clip (anywhere from 2-4 AA batteries will work fine.  The instructable uses a 9V battery with a 5V regulator.  This will work, but is a waste of time – this chip is good up to 6V.  If it were good up to 5V, I’d use 3 AA batteries) and a 1/4” jack, I will now have a guitar headphone amplifier.  I don’t need to add a volume control – it already has one.  And if I choose to use a stereo 1/4 jack, I can use that as a power switch by wiring the negative terminal of the battery connector to the ground of the jack and the non-tip connector of the jack to the ground connection on the board.  There is even an existing LED waiting to be used as a power indicator.

Published Tuesday, November 17, 2009 10:56 AM by Steve Hawley


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