When I first started with DIY audio, I had to use the desk in my garden shed/office for projects. This was never ideal as I frequently work from home for my job at this desk and had to keep packing equipment and components away. After Idiot Child No.2 left home, I moved my electronics to a desk in her old room. Whilst this is a considerable improvement, there is one aspect that is less than satisfactory, and that is a lack of space for my laptop. If I have the laptop out on the desk there is little room for anything else, but I find I often need to refer to material, e.g. datasheets, build information, component suppliers websites and so on, when I’m working on a project. I tried using my tablet but the screen size was a limitation and I prefer using a keyboard and mouse. I started thinking of a way round this and decided a small computer that I could put on my little HiFi rack with a monitor on the wall would be a good solution.
Thinking about my realistic use scenario, I wanted to spend as little as possible on this as I only really need a web browser, spreadsheet for BOMs and pdf viewer. This ruled out the Intel NUC form factor computers as the cost is too high. The recent launch of the Raspberry Pi 4 is timely and this new iteration seems like it should be more than capable. Whilst the specs are a significant improvement over previous models, there appears to be a slight problem with heat. The provision of a fan appears to mitigate against thermal throttling and for the light use it will be getting, this most likely not an issue for me.
The next consideration was the screen. I didn’t want to buy a new one so started looking at used models on the usual sites until I remembered that I had some old laptops in the shed that I’d rescued from people who were about to dispose of them. I’d managed to construct one complete working laptop using parts from others but still had these lying around in the hope that I’d be able to salvage something else from them in the future. The screen from a Samsung looked quite good so I started searching online to see if I could utilise it. It seems this is quite common and relatively straightforward as long as you can get the screen model number. In essence, you need a way to connect the HDMI out (or other output) from your PC to the particular signal input connector that your screen uses (usually LVDS). You then need to find an LCD controller driver board that will work with your screen, although universal options are also available.
You can buy standalone boards or kits that include various options such as all the cables, inverters if necessary, control keypads, remote controls, cases and so on. I managed to find a kit for my screen on Ebay that cost £17.99 including postage, with outputs for HDMI, DVI, VGA and also audio. It requires a 12V 3A power supply so if you still have the laptop charger (typically 19-20V) you could use a step-down converter. As I didn’t have a spare I had to purchase a 12V 3A AC-DC transformer.
The final stage will be to find some way of mounting the screen and control board into a frame of some sort and then attaching that to the wall.
The total cost for the project is £98, this includes
- Raspberry Pi 4 with 4GB RAM – £53
- Official Raspberry Pi power supply 5V 3A – £8
- LCD Controller board – £18
- Controller board power supply 12V 3A – £12
- Keyboard and mouse – £7
- Reused laptop screen – £0