Your First Circuit - Experiment 3

For those of you who missed my first two blog posts, “Taste the Power! – Experiment 1” and “Let’s Abuse a Battery! - Experiment 2”, I recently got the second edition of “Make: Electronics” by Charles Platt and decided to try all of the experiments presented in the book. This is my documentation of how the third experiment turned out.

It’s time, people, time to light up some LEDs!!!

Lighting an LED

So, the thing is, I didn’t have a 2.2 KΩ resistor on hand, as you can see in the picture above (now that you know how to decode the value of resistors from the Fundamentals: Decoding Resistors section of the “Make: Electronics” book).

My resistor is Red Black Red Gold = 2 0 2 5% = 2000 Ohms with a 5% tolerance.

A 2.2 KΩ (2200 Ω) resistor would show the colors Red Red Red Gold = 2 2 2 5% = 2200 Ω, 5% tolerance.

Still, the resistor is perfectly usable for the educational lesson the experiment wishes to transmit, which is: How does resistance affect current?

Here are the other resistors that will be tested (1 KΩ on the left and 470 Ω on the right):

So, let’s begin!

It’s alive!!!… ever so slightly.

Circuit with a 2 KΩ resistor

Now it’s time for the 470 Ω and 1 KΩ resistors.

Circuit with a 1 KΩ resistor and Circuit with a 470 Ω resistor (respectively)

As the resistance is decreased (by changing the resistor) the LED shines more brightly since more current is going through it!

Checking a Resistor

These are the values the color coding of each resistor translates into.

The first resistor is 2 KΩ (and not 2.2 kΩ as specified in the book). The multi-meter shows a value of 1.993 KΩ which is within the tolerance specified by the golden stripe (5%).

The 1 KΩ and 470 Ω resistors are the right value since they are within tolerance.

You can get everything you need for this experiment from DigiKey!

Everything you need to perform this experiment yourself is available from DigiKey:

• Test leads with alligator clips at each end
• Make: Electronics 2^nd Edition
• Multimeter (consult the first chapter of the book to see choose the one will best fit your needs)

The multimeter I’ve been using is the EXTECH’s EX330

• 9 V Battery
• Resistors
  • 470 Ω (5% tolerance)
  • 1 KΩ (5% tolerance)
  • 2.2 KΩ (5% tolerance)
• Generic LED

EXTRA

Here’s a tool to help you decode the resistor color code, try testing yourself using DigiKey’s Resistor Color Code Calculator.

The scientist introduced by the book during this experiment is Andre Marie Ampere. You can watch the following YouTube video to learn more about his life and experiments. André-Marie Ampère ~ Electromagnetism.