Solar Powered Indoor Night Light AA Joule Thief

A night light from one AA battery that can be powered by a solar panel.

It can also be used as a flashlight during power outages if the LED is not masked by an opaque cover.

Here, the design is powered by a AA battery. A solar panel can be added to the power supply input.

The NiMH 2500mah battery will last several months without the solar panel.

Note:   Danger of Eye Damage From Visible Light Emitting Diodes

This model uses a simple Joule Thief, BC337 transistors, and I added the LDR and a 100 uF electrolytic capacitor. For indoor use, you can use up to a 3 volt solar panel, as indoor light will not deliver as much voltage as a solar panel would when used outdoors. The LED is a "super bright" 10 mm LED.

Solar Powered Indoor Night Light AA Joule Thief schematic by Dave Hamm

Shown here without the solar panel.

Modified from "Solar Powered Garden Light" by Dick Cappels, (modified from mrpiggs). His arrangement does not use the LDR (Light Detecting Resistor), and used a center tapped transformer. The idea of their model was for outdoor use, and depended upon the solar panel to detect light.

Solar Powered Indoor Night Light AA Joule Thief on a breadboard

I wanted an indoor night light, so I added the LDR to better detect darkness while indoors.

Solar Powered Indoor AA Night Light Circuit Board Layout

Dick Cappels also used 2N4401 transistors, and had no capacitor.
Their model was modified from from a circuit design by Nick Baroni, of Willetton, Washington, and published on the siliconchip.com.au website. Dariusz Flaga in Poland, noted that the BC338 is a good fit for this application.

Reference:

Solar Powered Garden Light
http://cappels.org/dproj/ledpage/leddrv.htm#Solar_Powered_Garden_Light

Circuit design by Nick Baroni, of Willetton, Washingtonhttp://siliconchip.com.au