Supercap Lights Your Way In Times Of Need

You won’t find [Antoine] stumbling around in the dark. He just finished working on this LED flashlight which draws power from a super-capacitor (translated). He realized that lighting a high-efficiency LED takes so little power that there are many benefits in play when deciding to move away from batteries. When compared to a super capacitor, batteries have a shorter life span, are heavier, and take up more space.

The biggest drawback of a super capacitor in this situation is the low voltage operation. The output will start at 2.7V and drop as the current is discharged. [Antoine] used one of our favorite simple circuits to overcome this issue, the Joule Thief. That circuit is commonly seen paired with an LED in order to boost input voltage to a usable level. That’s precisely what’s going on here.

The final hack in his circuit is the addition of that red LED which you can see in the middle of the board. This takes the place of a Zener diode and drops the charging voltage to a safe level. That indicator light will not come on until the cap is fully topped off. This way it tells you when the device is done charging.

Generate Electricity With A Candle

What you see above is a generator that converts heat to electricity. [Reukpower’s] thermoelectric lamp is one of those hacks that makes you scratch your head even though you understand why it should work. The heart of the system uses a Peltier cool, just like the thermoelectric solar generator. When there is a temperature differential from one side of the Peltier to the other a small current is generated.

In this case a candle heats one side and a heat sink cools the other. The tiny voltage picked up from the Peltier’s contacts is then boosted using a joule thief. We’ve seen LEDs powered with a joule thief before, benefiting from their own low power consumption. In this case, the boost circuit is scavenged from an emergency phone charger and probably achieves higher efficiency than if he had built it himself.