What was the first electronic component you played with?  It was probably a LED.  They’re fun to blink in patterns or learn to fade.  Most projects (and products) use them for useful indicators.

LEDs add magic to every electronics project.  Often not understand is what else you need to make that LED work correctly.  Learn what current limiting resistors do for LEDs and watch what happens when you don’t use one.

The most common mistake is to use a LED without a current limiting resistor.

For this video, we look at how LEDs and Resistors work individually.  Then we hook them up together in a simple circuit.

We even go into the lab to get help from a couple of multimeters to see what happens when you do and don’t use a current limiting resistor.

Episode Notes

Components Shown

Here are some of the devices and products shown in the video.  There’s no connection between the vendors and me, it’s just where I found (or bought) the stuff from originally.  I’m sure there are others who sell the same.

• Avago Blue LED

  • PDF: http://www.avagotech.com/docs/AV02-0339EN

• TI TL5940 PWM Constant Current Driver

  • Product Page: http://www.ti.com/product/tlc5940

• Rigol Multimeter

  • Product Page: http://www.rigolna.com/products/digital-multimeters/dm3000/dm3058/

Engineering Resources

Here’s some resources to learn more about resistors, LEDs, Ohm’s Law, and an easy tool for calculating current limiting resistors.

• Ohm’s Law Tutorial:

  • http://www.baldengineer.com/blog/2013/12/31/unlike-speed-limits-ohms-law-isnt-a-suggestion/

• Tutorial on LEDs:

  • http://www.baldengineer.com/tutorials/led-basics/

• LED Calculator Wizard:

  • http://led.linear1.org/1led.wiz

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