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

DiscoverCircuits, has 25,000+ electronic circuits or schematics cross-referenced into 500+ categories.   As a vital resource for engineers, hobbyists, inventors & consultants, the site's collection of information will help you find quick solutions to electronic design problems.

Web www.discovercircuits.com

Modified LED Night Light
David A. Johnson, P.E.

Night Light - Front View - Looks like a mouse 

Night Light Front

Night Light Side View

Night Light Side

Night Light Bottom View

Night Light Back


Night Light inside with 3 LEDs

Night Light Inside with 3 LEDs

Night light insidewith 10 surface mount LEDs
Night light Inside
with 10 Surface Mount LEDs

Old light on left, modified light on right
Old light on left,
modified light on right

The circuit uses the classic series capacitor method to produce a current limiting LED driver, powered from the AC line.  The series capacitor forms a constant current source and will route the same amount of current through the parts, even if 3 or 30 LEDs were used in series.  This type of circuit made it much easier to insert 10 series wired LEDs instead of the three original devices.  I also switched from a NPN darlington driver circuit to a single n-channel FET. This made it easier to select the right resistor value to turn off the light in the day.  I set the required CdS cell resistance at about 100K, so anything less than that in resistance should keep the LEDs turned off.  I did have to change the resistor R2 to a 39v zener diode do limit the peak voltage across the filter capacitor C1, when the LEDs are turned off during daylight.

 Shake Flashlight Schematic

Sponsored Links


Sponsored Links

Electronic Consulting Engineers - design, development

Your Ad Here

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

Copyright  2002 - 2007 David A. Johnson & Associates.  All Rights Reserved to the contents & graphics of Discovercircuits.com
Linking is welcomed but COPYING any content or graphics to your server is expressly prohibited.