If you're flying an FPV RC plane or multirotor and find you have unwanted lines on the video image, you may want to add a power filter to you system.
This video demonstrates how a toroidal inductor and a capacitor can significantly reduce the amount of noise on the power feed to your FPV camera and thereby significantly improve the clarity and quality of the image it generates.
The Soft Ferrite Rings are available from HobbyKing for under $1 a piece (in a 5-pack) and you can pick up the required 470mfd capacitor from any number of sources - or just rip one out of an old computer or TV set. Just make sure that it's rated for at least 16V if you're using a 3S battery or 25V if you're using a 4S. And watch the polarity - it's important.
The enameled copper wire can be picked up in small reels from a hobby store or you can scavenge it for free from an old transformer if you feel so inclined.