Extreme Espresso, Part 2: An Inductive Water Level Sensor

[Mark Smith] must really, really like his coffee, at least judging by how much effort he’s put into tricking out his espresso machine.

This inductive water tank sensor is part of a series of innovations [Mark] has added to his high-end Rancilio Silvia machine — we assume there are those that would quibble with that characterization, but 800 bucks is a lot to spend for a coffee maker in our books. We recently featured a host of mods he made to the machine as part of the “Espresso Connect” project, which includes a cool Nixie tube bar graph to indicate the water level in the machine. That display is driven by this sensor, the details of which [Mark] has now shared. The sensor straddles the wall of the 1.7-liter water tank, so no penetrations are needed. Inside the tanks is a track that guides a copper and PETG float that’s sealed with food-safe epoxy resin.

Directly adjacent to the float track on the outside of the tank is a long PCB with a couple of long, sinuous traces. These connect to an LX3302A inductive sensor IC, which reads the position of the copper slug inside the float. That simplifies the process greatly; [Mark] goes into great detail about the design and calibration of the sensor board, as well as hooking it into the Raspberry Pi Zero that lies at the heart of “Espresso Connect’. Altogether, the mods make for a precisely measured dose of espresso, as seen in the video below.

We’d say this was maybe a bit far to go for the perfect cup of coffee, but we sure respect the effort. And we think this inductive sensor method has a lot of non-caffeinated applications that probably bear exploration.

25 thoughts on “Extreme Espresso, Part 2: An Inductive Water Level Sensor

      1. The previous article right here on Hackaday was literally about inadvertently re-inventing something that already exists. My only gripe is that Misterlaneous didn’t include a link or at least some good search terms.

  1. “high-end Rancilio Silvia machine” should read “entry level Rancillio machine.” It’s a single boiler machine, it’s a step up from a big box expresso maker but it’s absolutely not a “high-end” machine. My Silvia was 3 machines ago, granted it was a workhorse that never went down, and my friend that I sold it to still uses it 10 years later. My current machine is a Quick Mill Vetrano 2B Evo, and it’s not even a “high end” machine at $2900 it’s a hard plumbed, dual boiler dual pid rotary pump machine.
    I also understand that’s not what the article is about, that was the cool thing about the Silvia, it’s easy to mod and parts are cheep if you do manage to mess something up.

      1. If you don’t know the answer then you should buy it. You are clearly starting out with true espresso, that machine will be good enough for you to learn whether you really like messing around with the process or just like good coffee, and if you do, you can play with beans and roasts and grinds and tools and the like until it is eventually holding you back.

    1. We get it, your life is incredibly dull and your self-esteem is on the low side today, so you have to find some way to assert your superiority to the 99.9999% of people who are sensible and wouldn’t buy enterprise-grade equipment to make their morning coffee, and who would correctly consider a $800 coffee machine to be a high-end device in relation to a consumer’s needs.

      1. Ehhh I’ll bite. Dude said his expensive machine was not even high end and he is right. I’ll guess you haven’t priced out high end machines yourself that quoted amt of money isn’t really a flex. Objectively $800 is a lot of money, but in the scale of these types of things it really is entry level.

        Also “coffee machine” is enclose a different thing than an espresso machine. A Mr Coffee from a garage sale is a coffee machine. Espresso is a high pressure, high temperature process that at bare minimum requires a certain level of engineering to be safe to use. This costs money.

        I’m personally just like the other guy- I’ve outgrown my Mrs Silvia equivalent machine. I got mine used from a friend, a Gaggia (Lady Gaggia if you must know) and after maxing out that very good entry level machine I can’t quite justify a new one. But very simple things like being able to pull more than a double shot for personal consumption back to back are not possible with with entry level machines. It’s frustrating to talk about your espresso game then say yeah but like, in a half hour I can make you a latte.

        1. I justify the machine to myself as this, a late is $5 more or less, if you get one every morning for a year that’s $1825, or $3650 if your significant other drinks coffee, milk costs about 47 cents and the coffee is almost an after thought, but we go through about 2 lbs a month. So milk wise we go through about $343 a year, green coffee costs about $5 a lb. So $120 a year in coffee beans.
          $3650 – $343 – 120= $3187 per year in savings, I’m saving $287 in my first year. I have had this one for 3 years, so I have saved $6652 over 3 years.
          Also to the guy above that was asking about the Sylvia, it’s a decent machine, but it’s the grinder that you need to make sure is top notch or you’ll not like the Sylvia, or any machine for that matter.
          as a foot note, I built a coffee roaster just to feed my addiction, and that’s where hacking can be the most beneficial, it’s actually a fun field to get into.

          1. I never understood this fallacy to compare home coffee with overpriced store coffee. The same goes for beer. Unless the barista lives directly below me, do you expect me to walk in pyjamas to their store in the morning?

            That said, these calculations for savings are a miscalculation either way. Machines at price tags >2000 USD are the “audiophile equipment” version of coffee brewing. I’m sure you can taste a difference, but let’s be completely honest. If I already achieve 95% of the possible flavour, does it matter to one-up it to 99% of what I potentially achieve with a better machine?

            In the end even a hipster grinding manually and putting it in his glass labware style vacuum brew™ machine just does it to impress others. Like I said, I believe that you taste a difference, it just isn’t as impressive to the average joe who is just happy for his legal stimulant not tasting like boiled dirt. I take good beans over a good machine any day.

      2. My machine isn’t enterprise grade, at all. Enterprise grade machines even broken ones sell in the $2-5000 range, and new ones start at about 10-15k and go north of 30k easily, I wasn’t posting to feel superior, I was posting because I feel that the machine in question is not what it was described to be. It’s quite seldom I read an article on hackaday (despite reading 2/3 of them) that I genuinely relate to and about a subject I am passionate about.
        Most people will pay way more money to support a hobby they are passionate about, I guess I’m lucky I’m not passionate about sports bikes or fast cars, as those are exponentially more expensive.

      3. The amusing thing with your pointlessly vitriolic reply is it clearly indicates your own lack of self-esteem and feelings of inadequacy.

        Try some therapy, deal with your rejection issues and learn to not care that in the world of espresso machines, this is a worthy but very much entry level prosumer machine, with a massive modding community.

      4. We get it, your life is incredibly dull and your self esteem is on the low side, so you need some way to assert your superiority to someone who has an interest in something you don’t value and don’t have any knowledge of. That’s what Hackaday is about isn’t it? Only doing what 99.9999% of sensible people do? Good job.

      5. Chill, man. As with any interest, the deeper you get in, the more expensive it gets. For example, my laptop originally cost $900. To some, that’s expensive, to others, that’s impossibly cheap. I’m not a gamer so as I long as I can run CAD, I’m cool. A gamer might have a $3500 desktop. A person with no interest in computing might only own a smartphone and no laptop at all. Point being, to the uninitiated, $800 is a lot. To the serious coffee person, it’s indeed entry-level for a “real” espresso machine. If HaD posted a computer mod and called an $800 computer high-end, people would deride that to no end.

        Me, I bought a broken Nuova Simonelli Oscar (~$1200 new) for $200 and put about $150 worth of parts and a whole bunch of labor into it. It’s basically impossible to get good, consistent espresso out of a cheap machine. That’s just how it is.

    2. Yeah, the Silvia is pretty much the upper end of entry-level espresso machines. Never understood why so many people like to mod these things. You can put a PID or whatever other gadgets on it, but you’re still stuck an SBDU (single boiler dual use, the standard entry-level espresso machine config) machine. For what the mods cost, you might as well have just bought a heat exchanger or dual boiler machine.

      As for price, yeah, unfortunately espresso is in a whole different league than other forms of coffee. You’re dealing with a pressurized system, and all the engineering requirements that go along with it. It gets real expensive real fast. You almost have to treat it as a hobby as much as anything.

    3. You’re correct. But the Silvia is a good solid machine – mine is used daily and is now over 10 years old and has never broken down. All spare parts are available online and reasonably priced so if it did break then fixing it is no problem. The first thing I’d upgrade though is of course the grinder – you should spend at least the same amount on a grinder as on the machine, more if you can afford it. That’s advice for others, you know it already clearly.

  2. Just made 2 capacitive level sensors for my camper plastic water tanks. 2 50mm wide aluminium tape strips separated 5mm stuck side by side on the outside of the tanks make a variable capacitor that a regular 555 uses to generate a frequency as the water level changes the dielectric constant of the capacitor . The PLC that controls the rest of the features counts this frequency and displays the level.

  3. I’d be interested to gauge how many espressos are still in my tank, and I wonder if a good-enough water level sensor would also be possible using one of those time-of-flight distance sensors like the VL53L0X?

    As the amount of water per espresso is rather high, so precision may not be too important here. Would the surface of the water in the tank be sufficient to get a distance measurement?

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