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Building the controller
02/01/2016 at 11:38 • 0 commentsAfter I had a working prototype on breadboard the final controller was built into a small plastic project box:
with a female D-Sub connector to match the connector on the machine:
The final result with blue LCD and four buttons:
Yeah, I know, it's pretty ugly and it definately won't win any design prizes, but it works :-)
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Controller prototype
02/01/2016 at 11:27 • 0 comments -
Modifying the machine
02/01/2016 at 10:46 • 0 commentsWhile comtemplating what to do with the machine I stumbled upon this post:
http://coffeegeek.com/forums/espresso/machinemods/522994
It seems like this machine wasn't really optimally designed from the beginning. By adjusting the existing over-pressure valve I managed to get much better results from the machine.
But still those crummy mechanical bimetal thermostats were annoying me, and I needed some automation.
At first I used a couple of cheap industrial timers and a PID controller along with some solid-state relays to control the pump, grinder motor and heater, but they were clumsy and impractical so I decided to modify the machine for an external MCU-based controller.
I kept the solid-state relays, replaced the PID sensor with a LM35T and connected the appropriate wires to a D-Sub 9 connector on the front panel instead of the original switches.
After testing that everything was working using the connector, I was ready to move on to building the controller...