Here's a demonstration of the High-Efficiency LED + AP2502 Current Sink being powered by my Hybrid Wireless JT system.
The 10F reservoir capacitor can power the JT/LED combo for a long time, with brilliant light output from the LED.
The AP2502 acts to regulate the current in the LED to 20 mA when DC-powered, and also allows PWM control of brightness. Here I've simply connected the Enable pin to the positive supply lead, and the Joule Thief is providing an interrupted drive power to the LEDs.
With this arrangement, the LEDs can be driven with lower voltage from the capacitor or other source. And the efficiency of the LED means that it is producing a good deal of light, without much waste heat, for the low electrical input power of just a few milliWatts on average.
The parts were donated by a kind friend of TKLabs. Thanks again!
The Hybrid Wireless JT itself is fully described in another earlier video. The LED is a Philips Lumileds MXA7-PW57-H001.