Category Archives: failure!

basic analog circuits: vol. 1

Taking a circuits class with no breadboarding or solder experience has been a huge push away from comfort for me this semester.

It’s been that feeling of wondering, “Jeez, am I the last person in this class to get this?”

it me

Slowly, more than I realize, I’m gaining confidence with reading schematics, designing a breadboard, also debugging.

I wanted to share some of the lab projects from the semester. Some circuits took me weeks just to get right. None of them worked perfectly on the first try. I think that’s really important!

The class emphasizes making things over knowing perfect knowledge, so I don’t know how many of them work in detail. Some black boxes will remain black boxes.

1 – variable voltage divider

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This is a power supply. It takes in AC current and using a transformer unit, transforms that current into DC.

The AC is first directed through the big transformer, which I soldered to the AC wire (and almost electrocuted myself, whoops)


A bridge rectifier made up of diodes forces the current to be (+) instead of fluctuating between (+), ground, and (-).

There’s a massive capacitor storing the charge. I can turn the potentiometer and I can control how much electricity comes out the top two pins.


I use this one as a power supply when testing circuits now. Really satisfying that it works.
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cam doodler

doodle your world via webcam!
fool your foes! impress your friends! 👀

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check out the demo:

look at what these awesome people made:


code version:
play version:

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LCD works!

After endless struggles in week 6, I took some time after class and finally got the LCD screen to work. It turns out, soldering all the pin connections did the trick!

(message when plant is well-watered)

(aerial view of wirings)


I mounted the whole thing on an acrylic storage tray from Muji. It now plugs into the wall directly too. I would like to program the piezo speaker to chime when the sensor threshold goes from “wet” —> “dry.”

I felt really proud after debugging the system. This one was the most finnicky hardware project I’ve done yet, and I managed to get all the sensors working after many many failed tries. 💪🌱

new toys: rain sensor, LCD

For this week, I wanted to make a plant interface which could tell you if the plant needed water. (I have a soft spot for this “Internet of Plants” future…)

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Here are all the parts at play. Note that it doesn’t work (yet.)


I definitely upped the ante on myself this week! This post will mainly be about my process and struggles.

I spent most of my time playing around with these two new sensors….

This lovely rain sensor:

… and this very finnicky 16×2 liquid crystal display (LCD):


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