Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com, has 40,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.
We make every effort to link to original material posted by the designer. 
Please let us if you would like us to link to or post your design.

HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches

Circuits designed by David Johnson, P.E.
Last Updated on: Friday, November 17, 2017 06:32 AM

Master Category List - Dave's Circuits

The contents & graphics of Discovercircuits.com are copyright protected.
LINKING to Dave's circuits is permitted but DO NOT COPY any files to your WEB SITE server



More  Solar Cell Circuits, LED (Light Emitting Diodes) Circuits

Improved Solar LED Spot Light     February 1, 2013

Nearly all the Chinese made solar powered LED lights I see being sold at Lowe's and Home Depot home improvement centers are poorly designed.  Their solar panels and battery packs are all undersized.  The light from their Chinese made LEDs fade rapidly and the devices never make it through a complete night before the light dies.  I have been buying some of these poorly designed devices and modifying them, so they perform to my satisfaction.  In this example, I gutted the Lowe's spot light device shown below and installed proper components. 

I first replaced the original single dim T 1 size LED with a brighter, longer lasting part made by Cree.  The undersized solar panel was peeled away from the top of the assembly and replaced with a larger 5v 150ma solar panel. I used some black caulk to hold the panel in place and to seal it from the weather. The original small 250ma-hour lithium ion battery was replaced with a larger 2200 ma-hour cell. I removed the original control board and replaced it with a more efficient circuit design shown below.  That circuit used a low voltage drop battery charge controller IC to insure the lithium battery was charged properly to a voltage of 4.2 volts. I then used a LED current control circuit which only had a 0.05 volt drop.  That circuit used a single low power op Amp.  Finally, I used the voltage developed across the solar panel as a day/night sensor, turning on the light only when the solar panel voltage dropped to a low level.  The result was a light which was much brighter and lasted for several days, even under cloudy conditions.
Original Light  10 cell 5v 150ma Solar Panel
3.7v 2.2 Amp-hour Lithium Ion Cell Cree White LED

Click on Drawing Below to view PDF version of Schematic

Improved Solar LED Spot Light designed by David Johnson, P.E.

More  Solar Cell Circuits, LED (Light Emitting Diodes) Circuits

Dave's Circuits by Category
eMail David A. Johnson, P.E. about this circuit


HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |    Privacy Policy

Copyright  2002 - 2015 David A. Johnson & Associates.  All Rights reserved. 
 Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.