As you light the candle-powered lamp and throw out some soothing background music with a candle-powered Bluetooth speaker, wouldn't it be good if you could add some candle-powered rotary speaker effects to your play along noodling? The brass eye-catcher pictured above has been named the Candela VibroPhase. It's a guitar effects unit like no other and creates a rotary speaker effect with a touch of phase, wah, vibrato and tremolo without the need for a battery or power brick – just an inexpensive tea candle.

The Candela VibroPhase is the brainchild of "mad scientist" Zachary Vex of ZVex Effects, a company known for pushing the tone envelope with such classics as the Fuzz Factory and the Box of Rock. The project began with an idea to add a phaser/vibrato unit to the company's line up and mushroomed from there into a mechanical work of steampunk art with a modern twist.

Vex developed a new current-starved circuit that could operate on the tiny amount of power resulting from candle light shining on small solar cells, mixed in a miniature Stirling heat engine to drive a spinning disc and added effect control in the shape of a neodymium sphere magnet. The end result is a delightfully hands-on guitar effects unit where the player needs to move components around, mount a custom effect disc, set the candle at the correct height and position and then fire it up.

Heat from the tea light powers the Stirling engine (celebrating its 200th anniversary this year) and is transformed into mechanical motion that drives a flywheel, which in turn spins a patterned disc. The pattern on the optical disc, which can be painted or taped on, shapes the sound created as light from the candle is repeatedly blocked or allowed through to four photo cells in the black and brass tube housing the audio circuit. An offset circle is reported to result in a "pleasing asymmetrical pulsation," for example. The user can also filter the amount of light hitting the photo cells.

The circuitry gets its power from the candle, too, thanks to two small monocrystalline solar cells that harvest its light, with a reported 9 volts at 0.33 mA of electricity resulting. Each tea light can burn for up to 5 hours and, to help prevent breeze-related flickering, the whole unit can be enclosed in a vented glass cloche. Players will, of course, still need a mains-powered amp to enjoy the effects produced, which range from subtle vibrato to Leslie-like phase.

The Candela VibroPhase is plugged into a footswitch sporting instrument input and mono output jacks. There's a knob on the black tube housing the vibrato/phaser circuit which can "make the speaker cabinet sound like it's moving around the room and spinning" or dial in some gentle vibrato, or somewhere inbetween. "You have to be in front of it to believe how 3D it sounds," said Vex. Moving the unit's one inch diameter magnet toward the edge of the heat engine's brass and gold flywheel slows down the spin, altering the effect.

The device tips the scales at around 15 lb (6.8 kg) and is said to take about 20 minutes to set up, and it does produce some mechanical noise when running. It first turned heads at last month's Winter NAMM, and ZVex Effects is now making the Candela VibroPhase available to buy. The lead time for production is 2 months and each unit will set you back US$5,900.

It will come with some starter modulation discs, though a player can create their own designs on standard-sized clear CD or DVD stack dummies for unique sounds. The video below introduces this mesmerizing effects unit and shows it in action.

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