The Zvex Candela VibroPhase is a candle-powered guitar effect the company calls a “highly adjustable take on the Univibe.” It uses two gear ratios on a Stirling engine that covers a 20:1 speed range when used with its eddy current brake, which is a 1″ diameter neodymium sphere magnet. The user can create modulation patterns/LFO wave shape and rhythm using its interchangeable optical control discs. Learn more at zvex.com.