Wiring tricks for the coffee machine

When modding a coffee machine, it is easy to overlook questions around just how to connect up the wiring. The space the wiring occupies can be very hot. Just the air can easily be over 70°C and if the wire touches the boiler itself, that can be well over 100°C. Some wires also have to carry fairly large currents and mains voltage. The large currents cause extra heating and the large currents and voltages both cause electromagnetic interference.

Here are some wiring tricks I have learnt over the years. Continue reading

Mounting the flow meter

I have struggled for years to find a good way to mount the flow meter on my pimped Gaggia Baby Class. Eventually, when I bought an old Gaggia Baby Twin, I had a look a the metal bracket Gaggia uses and that immediately gave me an idea. An old PC expansion card blanking plate, bent over, a notch filed on the end and a cable tie. A little bit of silicone glue for stability and viola! Continue reading

Gaggia Baby Twin front panel protocol

I recently got (and fixed) a broken Baby Twin off ebay. I want to experiment with the extra boiler. Anyway, it turns out the Twin talks to its front panel using a TWI based protocol. Here are my notes (which I made in an ASCII editor – enjoy the ASCII graphics and sorry about the scroll bar at the bottom): Continue reading

Doubling Gaggia Heating Power

[Update: in my rev 2 PID controller board, I am going to move the logic below onto the PCB. But for any controller which was not designed with this in mind, including the disc thermostats, the design below should work. As long as the controller can handle double the current through its switching circuit.]

Some time back, I pondered whether it might be possible to increase the boiler power of my Gaggia Baby Class so it heats up more quickly. I subsequently carried out the plan and love it. Here is what I did…

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Solved: temperature control

I am very pleased. For years, now, I have striven to develop a clean and simple temperature control algorithm for my coffee machine which gets it to a stable temperature in the minimum possible time. This weekend, I cracked it: two minutes to a stable 95°C on my Gaggia Baby Class with no oscillations at all1That’s not quite all that is needed – the brew head needs bringing up to temperature as well. But that’s a different topic and I’m still working on it. Two minutes is also not an absolute minimum because the boiler power can be increased. Also a topic for another day. For the purposes of this post, we’ll use the stock 1350W the machine shipped with..

This is how I did it…

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1. That’s not quite all that is needed – the brew head needs bringing up to temperature as well. But that’s a different topic and I’m still working on it. Two minutes is also not an absolute minimum because the boiler power can be increased. Also a topic for another day. For the purposes of this post, we’ll use the stock 1350W the machine shipped with.

Gaggia boiler specs

So, you’re obsessed with implementing the perfect temperature controller for your Gaggia Baby Class (or Classic or any other derived model)1Oh, you’re not: is it just me then?. You’ve realised that you really need to know the values of some important parameters and the only easy way to get those is to take the boiler apart. And you don’t want to do that2Are you sure you don’t? If you do, you can take the opportunity to improve the brew head temperature.. The good news is I’ve done it for you3Where I also took the opportunity to improve the brew head temperature.. Here is everything you need to know4At least, I hope so: I don’t want to take it apart again.: Continue reading

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1. Oh, you’re not: is it just me then?
2. Are you sure you don’t? If you do, you can take the opportunity to improve the brew head temperature.
3. Where I also took the opportunity to improve the brew head temperature.
4. At least, I hope so: I don’t want to take it apart again.

Improving Gaggia brew head temperature

Over recent weeks, I have wasted invested a lot of time investigating the Gaggia boiler thermodynamics. (All part of my master plan to have the entire machine at a stable temperature inside 2 minutes from power on.) A major obstacle to getting a stable temperature quickly is that the brew head takes for ever to warm up. Whilst thinking about this, I hit on an idea for improving the heat transfer from the aluminium boiler shell to the brew head: put heat-sink compound in the join between the shell and the brew head. Continue reading