Liz Arum's Blog » resistors http://blog.lizarum.com I teach tech and share it Thu, 29 Sep 2011 16:29:14 +0000 en hourly 1 http://wordpress.org/?v=3.1.3 Piranha Leds and LED Resistance Calculators http://blog.lizarum.com/2009/09/piranha-leds-and-led-resistance-calculators/ http://blog.lizarum.com/2009/09/piranha-leds-and-led-resistance-calculators/#comments Wed, 23 Sep 2009 01:08:37 +0000 Lizabeth Arum http://blog.lizarum.com/?p=77 It was the first Middle School Physical Computing class of the week today. Class was split between two activities. The first was lighting a 5mm Flux RGB LED piranha. While not told whether they had a common cathode or common anode LED, students were given the following information:
rgb_piranha
DC forward current 20mA
Red: 2V typ, 2.4V max
Green: 3V typ, 3.6V max
Blue: 3V typ, 3.6V max

After determining their resistor values, each student wired up their circuits to discover if their led was common cathode or common anode. Only one student managed to burn out the led by wiring both sides to power.

After creating some blended colors, students put the lights aside and went on to construct Evil Mad Scientists‘s LED Resistance Calculators.

Next class we’ll put the calculators to use and solve a few problems!

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