my "sun jar"
Tried to make my own "sun jar" around a year ago. Left it on breadboard until today...
Find the schematic below. Added a switch to keep the LED off all the time... which effective makes the whole thing a solar powered battery charger...
Notes to self:
Find the schematic below. Added a switch to keep the LED off all the time... which effective makes the whole thing a solar powered battery charger...
Notes to self:
- The solar panel is directly connected to the battery for charging. Without any control on voltage or current. May damage the battery in a long run. But then, the solar panel used is not that powerful... so....
- A normal LED requires more than 1 AA cell to power it up. To overcome this, the center-taped-coil and one of the transistor formed a switching circuit. It generates voltage high enough to light up the LED with less than one volt.
- Unlike the commercially available Sun Jar, this circuit doesn't use photoresistor to control when to light up the LED. Instead, a transistor is used to detect the voltage output of the solar panel.