Tim writes in:
What are the reasons we see light bulbs made up of lots of small LED’s instead of one large LED?
As Collin showed us in his excellent video about the subject, LEDs pass electricity through “dies,” or little chips cut from a larger wafer of semiconductor; there is just a small active area that’s actually lighting up, which is then reflected out in the desired direction. Engineers try to make the most efficient LED possible, which is linked to the size of this semiconductor as well as the heat it puts out, among other things. There is such a thing as a multi-die package, which puts more than one piece of semiconductor inside the same plastic casing. My favorite electrical engineer, Matt Mets, found me this interesting article comparing the efficiencies of single-die and multi-die packages for LEDs. Essentially, the maximum usable size of the semiconductor is limited, and there’s a limit to how many you can cram into one lens before the thing generates too much heat. On the practical side of your question, the market is just now seeing a boom in these “bulbs” containing many LEDs, like the one pictured above (image from Treehugger). The product designers for these things are buying off-the-shelf components and putting them together into a product, not engineering new LEDs… yet. We’re able to see a massive reduction in energy consumption with these LED bulbs when compared to incandescents, so the demand for an even more efficient model (perhaps using multi-die LEDs) hasn’t quite caught up to us yet. The takeaway: bigger isn’t always brighter!
Young maker Justis writes in:
I’ve just started out in electronics and I want to make some cool stuff! but alas, being a kid and all, I don’t have much time to bike to radioshack every time I need a resistor. How do you recommend I start gleaning things for projects?
Simple: you’ve got to build up a stash! Components aren’t that expensive, especially resistors. I’d recommend asking family members for gift certificates to Sparkfun, the Maker Shed, and even Amazon, which all carry excellent components and kits, and they’ll mail them right to you, no bike-riding required (work with your parents to ensure you’re buying form a reputable site). If you come across older devices at the thrift store, like VCRs and the like, they often contain full-size (not surface-mount) components that you can remove while you practice your de-soldering skills. When I was a kid, I was really into baking, so for every gift-giving holiday, I’d ask for a different item that I couldn’t afford myself, namely a stand mixer. If you make a wish list for those who might shop for you, include web addresses for particular products to ensure your non-savvy relatives get you the things you really want. To start with, I’d highly recommend the DIY Design Electronics Kit by Sparkle Labs. It comes with a great starter assortment of many different types of components in common varieties, so you won’t have to ride over to RadioShack quite so often. Show us what you make!
If you have additional advice for Tim or Justis, leave it in the comments! And if you have a question for MAKE about a project you’re working on, concept you’re trying to understand, or anything else related to the complicated life of makers, drop me a line at [email protected] (or record a video, tweet at us, etc.).