Temperature time, and a prototyping timesaver.

Another week, more parts have arrived for the coffee machine!

To save messing around with soldering and cutting more weird little cables I got myself an eBay knockoff of a RaspberryPi Prototyping Board, which exposes most of the pins I need as screw terminals. Once I get to the more permanent stage I can solder things to the included field.

After not receiving the MAX31855 breakout I tried for before xmas, I bought a MAX31865 breakout board from PlayingWithFusion.com. A neat, tiny little board which should get me some fine resolution temperature sensing!

MAX31865 prototype board from playingwithfusion.com

Sadly, mine is blue – purple didn’t seem to be available. :(

I don’t remember it, but I seem to have purchased the cheapest 2-wire PT100 sensor money could buy, which came with some terribly flimsy wires. I foresee buying another one in short order, once I’ve broken^wplayed with this one a bit.

I quickly updated the code to use the BCM pins – because that’s how the breakout is labelled – and have tested the connectors with my existing switches. All works so far, next up is to wire the power relay and then temperature sensing part in :)

Servicing a Miele Large Turbobrush STB 205-3

I bought a new vacuum cleaner recently – the Miele Complete C3 Cat&Dog. A great unit, with a charcoal filter to save me from puppy smells when vacuuming. It also comes with a “Large Turbobrush”, model STB 205-3 which is quite handy for picking up fur. Today I thoughtlessly sucked up the control cord and half the runs-along-the-bottom cord for my vertical blinds (the dogs trashed them months ago).

Inhaled the cordage
Inhaled the cordage

I got 90% of the cord out of the brush wheel, but some of it had been sucked into the part that actually provides the power to the brush. I tried jiggling things back and forth, but nothing would budge. Time to disassemble! Continue reading Servicing a Miele Large Turbobrush STB 205-3

A delay :(

Well that’s a pity. I had ordered a MAX31855 SPI thermocouple interface to capture temperatures on the coffee machine, and after waiting a month the sender’s just given me a refund because it didn’t get delivered. :(

Back to the drawing board – on a high note this means I might be able to get a MAX31865, which handles four wire PT100(0) sensors, which I have been told are much more reliable.

Coffee machine shenanigans

I’ve had a Rancilio Silvia for a bit over a year now, and it’s been great to make coffee while also saving money and reducing the amount of plastic I was dumping into the bin. One of the popular modifications to them is to install a PID controller to make the heater control more even, and because I’m always up for a challenge I wanted to make my own.

That, and I leave it on often enough that I’m grumpy with myself, as repeated most eloquently by a friend:

Quote of the month: “keep leaving the coffee machine on, figured I could build a timer, turns out I can build a coffee machine with an API and finer temperature control”

That’s awesome. You know who you are.

So the plan is to combine a Raspberry PI, a few Solid State Relays, a temperature sensor, some buttons and some wire to upgrade the interface of Miss Silvia :)

Since I’m a pythonista, I’m writing the control software in that, and I’m hosting it on Github – yaleman/CoffeeMachine.

So far I’ve got a simple control loop working, and it’ll accept input from the two buttons I have configured. It’ll turn “main power” on and off , has VERY simple (and untested) temperature control implemented, and it’ll turn itself off automatically after a set amount of time.

I’m still waiting on the temperature sensor and am pondering where all the parts will fit into the machine so that it’ll last a long time and not die of heat/vibrations/water.

Stay tuned! :)

The test bed. SSR top left, RPi on right
The test bed. SSR top left, RPi on right