The fear of breaking things

The fear of breaking things

In the time since I left you to ponder the etymology of anions and cations, and how that relates to anodes and cathodes, I have continued working my way through The Arduino Projects Book.  I built myself a simple circuit with a switch, a series circuit with a switch, and a parallel circuit with a switch. Then I moved over to the actually interesting projects, and right away I ran into something that left me confused.  Suddenly, without explanation, the circuits I’m instructed to build are putting the resistors on the cathode side of the LEDs I’m lighting up, instead of the anode side like they were before. Does order not matter?

Quick Googling and a run to the public library have both left me still in the dark.  Possibly this is because I was lured away from my intention of getting a kids’ book about circuits, and instead ended up with an introductory college textbook.  Bad idea!  Now I need to go back.  Or I could ask the audience.  Anyone have an answer in simple words that someone with zero background knowledge will understand?

Perhaps more important still, this nagging question has made me realize that I’m still in a stage where I’m afraid to experiment.  What will the consequences be if I try things in the other order, and order DOES end up mattering?  Will it just fail to work, or will I break something permanently?  If I do break something permanently, will it be the LED, or will it be the Arduino itself?  I’m much more willing to risk losing an LED than I am to risk losing my Arduino, but all the same I find myself wishing for crochet projects where I know ahead of time how hard it’s going to be to rip out my stitches.
Past experience tells me that I need to get past this fear of breaking things if I’m going to make real progress.  Until I do that, I’ll never even be able to modify the circuits I have instructions for, much less create something on my own!
Anyway, here’s a rundown of the things I’ve built so far:

A spaceship interface (TARDIS sounds unfortunately not included).

The Love-O-Meter:
Sharona tests the Love-O-Meter
The Love-O-Meter is supposed to measure someone’s hotness (literally, in degrees Celsius), and light up different numbers of LEDs depending on the person’s temperature.  I had to adjust the baseline temperature up 4 degrees Celsius because it was so hot in my house that day.  It was any easy fix in the code–nothing more than changing the value of the baselineTemp.  Sharona (@linguomancer) helped me test it out after I made the change.

This color-mixing lamp is supposed to change the color of its LED depending on what color the light is in the room around it. This is where I started to get creative, because how on *earth* are you supposed to make those gels stay put on top of the photoresistors? They kept falling off!
Color-mixing lamp, with uncooperative gels

Also, I wanted the LED to change colors.  What good is a color-mixing lamp if the LED never changes colors?  The only way it would change colors is if I moved the whole set-up to another room–at which point all the gels fell off *again*.

I may not know enough to rework the circuit in any meaningful way, but I do know enough to be able to change the code controlling what this thing does.  In the end, I reworked the code until I could make the LED fade from one color to another based on which photoresistor had the most light on it (here’s my code).  This is a video of what it looked like when I was finished.  Much more fun than the original!  I can make the LED fade from one color to the next just by hovering my finger over the various photoresistors.

That’s my progress so far!  Has anyone else made something cool?
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