The Idea …

So I’ve had my Miss Silvia now for five months. And in that time, I’ve managed to finess some fantastic shots from her. But there’s a routine that I must go through. Many who own a Silvia are fondly familiar with the idea of “temperature surfing” – that you catch Silvia at her warmest (and in this case, ideal temperature) by pulling water through the group head or steam arm until the boiler turns on, and then pulling your shot just after the boiler turns off. The reason for this is obligatory – in the quest for a reliable (admirably so) design, Silvia uses bi-metal thermostats to control how hot and bothered she gets. For non-technical folk, it means that the boiler temperature can fluctuate by up to 15°C (~30°F) and that translates to an inconsistent shot with a myriad of unwelcome flavours. That I pay reasonable money for my espresso beans, means that I want to enjoy the best possible flavour from my beans.

The Silvia is commonly modified (as I’ve seen online), and there are several kits that are sold to provide Silvia with optimal temperature control. The device is called a PID controller – a Proportional-Integral-Derivative controller (see the Wiki page if you want to know more).  The gist of it is that a PID installed on Silvia ought to provide reliable and accurate control of her innards. There are several kits available on the market that allow refined control of Silvia with a reasonably appealing aesthetic but with some caveats.

I’m a tinkerer, and when I’m presented with a problem, I like to reinvent the wheel. This for me means that rather than buy a PID kit, I’m going to design my own. The features that I want to include far exceed anything that’s available on the market, so it seems fitting to try my hands at this and learn a bit along the way.

My posts in this blog will be about design choices, the build process, successes, and downfalls. Ultimately, I hope to create something wonderful.

4 Replies to “The Idea …”

  1. just stumbled on your blog, and i’m a big fan! i’ve had my silvia for 2 months now and have been looking for sth that goes beyond the pidkit thing that’s available. your project seems to be just that 🙂

    which other features are you considering to implement? and how well does your pde temperature model work? were you able to validate that?

    cheers, max

    1. Hey Max!

      There’s a number of features that I’d like to implement – I’ve got a big appetite and want to maximize what I can get out of my final design.

      Aside from the hard features mentioned in the Brains and Brawns post:
      – 10 Programmable Presets w/ pre-infusion
      – Adjustable steam temperature – up to 155C
      – Real-time clock for auto-on / off
      – Auto back-flush w/ descaling reminder
      – Remote control using a Bluetooth module (thanks for the great idea Mike!!)
      – (Maybe) Capacitive water tank indicator

    1. Hey – Glad to see the interest! I’m working on the board now and have sourced some of the components for the final board. There’s a post to come soon as I wrap up the first revision of the firmware!

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