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

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

HOME Schematics Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches
Welcome to DiscoverCircuits.com - online since 2002

See Media Kit for
Advertising Opportunities

Attention Designers:  Please alert us by eMail if we have linked to sites
where your original material has been copied without your permission.
We will change to the LINK to your site.  
Thank you.

 

DiscoverCircuits.com -- Hobby Corner
Last Updated on: Wednesday, October 18, 2017 05:04 AM

Hobby Circuits List

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  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 Drawing Below to view PDF version of Schematic

Pot Controlled Variable LED Intensity Hobby CircuitDavid Johnson, P.E.

More  Drivers    Lamp Control     LED Circuits
White LEDs     Potentiometers

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

 


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


Discovercircuits.com endeavors to credit original designers.   Please alert us by eMail so we can
delete links to material that have been copied without your permission
.   Thank you.


© Copyright of all original material on this website is the property
of David A. Johnson, P.E. (Dave Johnson & Associates ) unless otherwise noted.  

Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.
All material is provided "as is" without guarantees or warranty of any kind, either expressed or implied.