If you want to avoid fires, malfunctions, and other accidents, it's not a bad idea to map out a circuit before you start soldering things together. Free web app CircuitLab is a free, web-based tool that might make things a bit easier: it's dead simple to place resistors, capacitors, batteries and way more onto the drawing board and connect it all together. The creators say that you're also able to simulate how your design will behave, and if it looks like you've got a problem you can reach out to the community to for some opinions by marking your schematic as public. Also, since it's web-based, it should work just fine on all platforms. It all sounds pretty great to us — we just hope it means we'll get to see more awesome DIY projects like this $200 quadrocopter.