Doug Conner of Atascadero, CA wrote in with his technique for testing Stirling Engines.

I’m running this engine from the heat of a 70W light bulb in the video, but It also runs well from the heat of two candles. Using higher heat sources it puts out over 1.5 watts. I need to redesign the engine so that it can run faster than the current limit of about 240 rpm to achieve higher power.