The basic machinery (heating element, solenoid valves, thermistor, silicone tubing, tank gasket) are the same as from a Curtis coffee brewer, but pretty much everything else was made from scratch from copper and stainless steel.

I have been developing this project for a local coffee house.


It's a microcontroller controlled 3 station pour-over machine. It times out hot water in 2 doses with a pause in between to drip down.

 
One of the dump valves with the RGB LED (ws2801 from sparkfun) controller above it.

 


This is the Sanguino Microcontroller (similar to an Arduino but with more pins) that keeps the tank full, regulates water temperature, times out the doses of hot water, and keeps the colors of the buttons updated. I use the cheap parallel displays, so they use 7 pins from the microcontroller.


I design my circuit boards with a pen and paper, scan them, clean them up, and print them out with a laser printer.

The Warning labels were also etched with toner transfer method. 


for temperature control, I am using a thermistor and a solid state relay (no PID at the moment, but it really isn't needed for this simple job). The 4 valves are controlled by optocoupler controlled BTA-10 triacs. Tank level sensing is done with a probe that sticks into the tank through a teflon bushing, a resistor (28K), a small 100pf cap, an assert pin, and a sense pin.

Art circuit board. Made with the toner transfer method.

The buttons are made from fiberglass and epoxy resin laid up in crude clay open face molds. They contact microswitches to get the message to the microcontroller. The program is based on sample intervals with a stage counter, so that takes care of de-bouncing.

I'm cleaning up the code and commenting it, and will post it here.
     


the coffe machine on duty!
Here it is at work at TH Benton's Coffee / Deli in Bentonville, AR.
So far, so good. I plugged it in to the laptop for a slight software upgrade today.
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