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On the second episode of Make: television I showed how to build an air cannon (Burrito Blaster) using PVC pipe and a sprinkler valve. The valve is electronically triggered, using three 9V batteries to activate a solenoid. But what’s actually going on inside to allow a tiny solenoid to hold back and then release a huge amount of air pressure? Well, the solenoid doesn’t do it by itself; it’s actually a “pilot” that opens a tiny hole to relieve pressure from a larger diaphragm that’s doing all the real work.
These diagrams and descriptions from The Spudgun Technology Center do a great job of explaining the clever trickery of the sprinkler valve.

John Edgar Park

John Edgar Park

John Edgar Park likes to make things and tell people about it. He works at Disney Research and writes for Make and Boing Boing. He is training for American Ninja Warrior. You can find him at jpixl.net and twitter @johnedgarpark — if you like that sort of thing.