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

DiscoverCircuits.com, has 45,000+ electronic circuits, cross-referenced into 500+ categories.
We have searched the web to help you find quick solutions & design ideas.

Got Designs?
Please eMail
if you want me to link to and/or post your original design
NOTE:  We make every effort to link to original material posted by the designer. 
Please contact us if our link is not to your site!  Thanks.

DiscoverCircuits.com -- Hobby Corner
Last Updated on: Tuesday, June 01, 2021 03:06 PM

Hobby Circuits List

The contents & graphics of Discovercircuits.com are copyright protected.
LINK to Dave's circuit, but DO NOT COPY any files to your WEB SITE server



More  Drivers    Lamp Control     LED Circuits
White LEDs     Potentiometers

Pot Controlled Variable LED Intensity Circuit --  September 24, 2009


The circuit below uses power from four rechargeable AA NiMH cells to drive 3 white LEDs.  A potentiometer varies the duty cycle of a pulse width modulator circuit to vary the intensity of the LEDs from 0% to 100%.  The beauty of the circuit is that when the pot is all the way toward 0%, very little power is drawn from the battery.  Likewise, when the pot slider is moved toward the 100% end, full power is fed to the LEDs.  In effect, the pot becomes the on/off switch.

A dual low power voltage comparator TLV3702 from Texas Instruments forms a simple PWM controller.  The comparator IC draws very low current and has push-pull outputs.  This lowers the total number of parts needed.  When the potís slider is in the off position, the total current should be about 6 microamps.  In the full on position, the current increases to about 60ma, or about 20ma for each white LED.  If quality 2500ma-hour batteries are used, the lights should last a day and a half.
Rotary Pot Slide Pot
Rotary Pot Slide Pot

Click on Circuit Below to view PDF of Schematic

Pot Controlled Variable LED Intensity Hobby Circuit by David Johnson, P.E. (September 24, 2009)

More  Drivers    Lamp Control     LED Circuits
White LEDs     Potentiometers

Hobby Circuits List
eMail David A. Johnson, P.E. about this circuit


HOME Schematics Index Hobby Corner Dave's Circuits Contact Info
Imagineering Ezine Dave Johnson & Associates Faraday Touch Switches


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

Copyright  January, 1998 - June, 2021     David A. Johnson  All Rights reserved. 
 Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.