Step 8: Adding Extras.
Several months after finishing this project I still feel the urge to add further functionality to my portable solar generator. Since my headunit has a front USB port I used a traditional 4GB flash memory stick, trouble is that 4GB isn't much space for music and large memory sticks of 32GB or larger are a bit pricy, I thought why not buy a USB powered hard disk drive and incorporate it into my box. I visited Curry's electricals and purchased a Western Digital Bus Powered SE 500GB drive for £39.99.
Being an external box it was prone to knocks and drops so I decided to mount it inside my solar generator with a separate USB port on the side so a separate cable can be connected to this port and then to the headunit, or even to the PC to edit music on the drive. Another problem appeared, with the drive mounted inside I couldn't see the LED indicator to make sure it was safe to unplug the drive, therefore it was necessary to have an external LED mounted on my box. I designed a circuit that uses an LDR blu-tacked to the hard disk drive LED to flash when the HDD light flashed, instead of opening the drive and physically connecting an external LED that would void the drives warranty. The circuit diagram is shown here, designed to run off 12 VDC to power an LED between 2-3 volts in my case, an LED mounted tidily in a 3mm panel mount clip from Maplin's for 34p. Now I can have my music powered by the sun, currently I have 2700+ songs on my HDD, however my particular Sony headunit can only read 128 Albums max at 500 Songs per folder, this is a problem for me because I can't fit all my music on that I'd like to.