Arduino Forum

Using Arduino => LEDs and Multiplexing => Topic started by: wmcglass on Jun 11, 2014, 06:10 pm

Title: 5V power source with LilyPad Micro LEDs
Post by: wmcglass on Jun 11, 2014, 06:10 pm
Hello there!

I've got a project where I am controlling some of the Lilypad Micro LEDs with an Arduino Lilypad 328 Main Board.  I'm powering the project with a Lilypad LiPower board and a 3.7V LiPo battery.  When I purchased the LiPower board, I didn't realize that it converts the 3.7V LiPo source into a 5V source.  I am now worried about burning out the Micro LEDs, as they do not have a resistor, and the datasheets read the forward voltage as between 2.0v and 3.3v, with a maximum of between 2.4v and 3.8v, depending on the color.  I've noticed that the LEDs are noticeably brighter than on the previous project where I used a coin cell battery.  The LEDs are connected to the Lilypad main board using 30awg wire wrapping wire, so my guess is there isn't a lot of resistance there, but I am new to hobby electronics.

All that said, should I be concerned about burning out the LEDs?  The LEDs aren't powered on continously.  The project is actually reading an analog value from a microphone and powering the LEDs based on the volume level (VU Meter), and so the LEDs power on and off multiple times a second.  Thanks in advance for your feedback!

William
Title: Re: 5V power source with LilyPad Micro LEDs
Post by: CrossRoads on Jun 11, 2014, 06:12 pm
Yes, you should be concerned about burning out the LEDs. At higher unlimited currents their life is greatly reduced from over heating. Add some series resistors right away.
Title: Re: 5V power source with LilyPad Micro LEDs
Post by: wmcglass on Jun 15, 2014, 07:34 am
Thank you for your reply, CrossRoads!  I really appreciate it.

Cheers,
William