The Coffee Pot: Unboxing

I had never really considered how a coffee maker functioned before. The general process of getting the water hot, and then dumping it on the grounds is obvious, but how does the machine make it happen? How does it move the water from the reservoir to the basket with the grounds? How does it know when the water is hot enough? How does it do these things with components that come together and sell for profit at a shelf price of $10?

 

These are not questions that typically occur to me, especially at the time of day and state of mind that leads me to seek caffeine. They occurred to me as I was opening up my coffee pot, but even then... not really in any depth. I figured the switch would heat the reservoir and then it would have some sort of temp sensor and a comparator, and once a level was reached the water would be dumped into the basket with the grounds.

That method would work... but probably not for a product with a sale price of $10. It also would not work for a product where the reservoir and the grounds basket exist side by side, a fact that somehow escaped me. I'm an electrical engineer, dammit! I think in circuits, not... with my eyes???

Anyway, before we get to how this thing functions, I have someone for you to meet:

If this screw had his way, I would not be typing this right now. Instead, I would be googling methods of fashioning custom screw drivers out of melted plastic, and other atrocities.

Thankfully, the plastic on the bottom of the coffee pot is so bendy, I could just release the latches on the back, and fold it away.

 So... There is basically nothing in here. This should not have surprised me. I mean this coffee pot was purchased for $10.

The external switch connects the high side of the AC wall voltage to a heating element. There are two resistors in series with the heating element that I am guessing regulate the current through the element, which is probably cheaper than manufacturing what would basically amount to a horseshoe shape ceramic resistor.

I saw and took a sniff of the white stuff on the edges of the heating element. It's thermal paste! the heating element is not welded to the plate the pot sits on, it is pressed onto by the cross beam seen above. Kind of interesting?

Finally, for completion sake, we have a shot into the reservoir:

I drew a model to help visualize the system:

So the switch is turned on after the reservoir and grounds are loaded (or before, but why would you do that?). The water conduit in the bottom, and the plate that heats the pot are joined to the heating element by compression and thermal paste. As the water heats up it climbs the conduit until escaping into the basket, where it soaks the grounds, and coffee happens.

Next time I will compare the findings of my deconstruction to my design objectives from the previous post and discuss solutions. See you then!

Project 1: The Coffee Pot

I do not drink coffee. I don't like it black and feel silly loading it up with cream and sugar. Even a tea man such as myself can see flaws in the coffee pot feature set though.

Programmable brewing is nice... But what if I don't get up at the same time every day? What if the power goes out and resets the clock? What if I forget to put water in it? What if I forget to turn it off?

So what are we looking at?

Market Research: Browsing coffee pots in Walmart a year ago.

Side note: There may be realized solutions on the shelf today that do not void a warranty. However, keep in mind that the primary motive of this and future projects is not altruism, but a selfish desire to increase my utility as an embedded system designer.

Base Goals:
-Remote Start
-Activity Sense On/Off
-Clock that retains setting through power outage
-Indication for lack of water/grounds
-Brew Complete Buzzer

Stretch Goals:
-Web Interface
-Brew Temp Control

The setup I have in mind right now will use a couple of MSP430s to setup a ZigBee network, consisting of a remote that will control the coffee pot, and a controller I can keep next to my bed. The controller will be expandable so I can add future home automation devices to it (you know, in case I want to open the garage while I'm in bed... Or something)

NEXT TIME: opening up the $10 coffee pot I bough at Walmart. Complete with #gutshots!!!!

RESET

There's not really a good way to address my treatment of time other than saying some resolutions fall apart.

I have not been blogging, obviously, so what have I been doing?

I gained a rudimentary knowledge of C++, changed jobs, and increased the length of my unfinished projects lists! Why is it so much easier to come up with ideas than it is to like, you know... do all of the tedious stuff necessary to complete them?

Well, mainly because daydreams are the fun part! Figuring out why your ARM launchpad keeps hanging up when you try to configure the PLL? Not so much.

My solution to this is to pick single projects and work on them until they are finished. I will hold myself accountable by making a blog post every Sunday.

The solution to being a flighty dreamer is to be more focused #FACT

The Lord accepts scheduled blog entries as praise #WHYNOT

That being said, I will reveal my first project, along with some sort of software/hardware requirements on Sunday July 13th.