So it turns out capacitors are actually pretty fun to play with. As you can see from the live feed image of me charging and discharging it over and over endlessly hahaha…. No seriously I spent a ton of time doing this and you should too.
Section 3 Lesson 8 is a great introduction to buttons and capacitors. It has some easy to understand analogies and it’s project is (pretty) easy to follow along with.
Warning: If you like to tinker, buy more than one LED
As one might imagine I burnt more than a few LEDs on this project. Getting the project setup correctly isn’t hard at all but I learn by building, breaking and building again. Unfortunately breaking means burning bulbs. You don’t even get any magic smoke 🙁 The good news is that LEDs are super cheap and I bought a box of them on Amazon for around $5. A worthy investment and happy addition to my hardware collection.
The book does a good job explaining the difference between capacitors, how to use them and how they work. I like the parallels the book draws between water containers and capacitors. One thing I didn’t see though was an easy to understand explanation on the discharge rate of capacitors. More to come on this below.
Being naturally curious, and having a brand new Saleae Logic 4 in my hardware hacking toolkit, I decided to see what the capacitor discharge rate looked like. As you can see from the photo, I hooked the leads up to the negative side on the capacitor and the positive side of the LED. No particular reasons behind this. I figured the reading at the LED would be most relevant for this circuit.
I had an idea what the output would look like but I didn’t necessarily know for sure. As expected, there is a spike in voltage, followed by a rapid decrease and then finally a steady decay until depletion.
If you’re interested in the reasoning behind this break out your calculus for dummies book because it’s going to be a stroll down delta of pain lane.
The long and short of it is the electrons want to move REALLY bad when the circuit is first closed. As they make it over to the other side though they start wanting it less and less. After a couple seconds they decide that this circuit has been a sham and they quit all together. It’s rather sad actually.
Okay well maybe that’s not exactly what happens but you get the idea. This chapter is well worth a read. It’s just in depth enough to work with these components and it provides just enough information to continue learning on your own if you want.
Author: Anthony Russell
Professional .NET Developer