Low water indicator for coffee maker couldn’t be simpler

low-water-indicator-for-coffee-maker

The coffee maker which [Donald Papp] uses every morning has a water reservoir on the back that can last for several days. This means he forgets to check it and from time to time will return to find that nothing has brewed. He decided to add a low-water indicator to the machine. His approach is about as simple as it gets and we admire that accomplishment.

If it were our project we’d probably try to complicate it in one way or another. The use of a microcontroller and ultrasonic rangefinder (like this tank level indicator from a February links post) would be overkill. No, [Donald] boiled down the electronics to a homemade switch, a blinking LED, and a battery. The switch is a flexible piece of metal attached to a plastic cap using some monofilament. The cap goes in the reservoir and floats until the water gets too low, it then pulls on that metal, completing a circuit between the battery and the LED. That’s it, problem solved.

Now he just needs to plumb the coffee maker into a water line and he’ll really be set.

Comments

  1. Geebles says:

    The simplicity is great! Far more reliable than an overpowered system, and as he said: “it is pretty much impossible to use less power than it does right now” :D

    • Hirudinea says:

      Just use a float, a straw (long stick, whatever) and a small hole drilled in the top, when you can’t see the straw sticking out of the hole refill the reservoir. Now that’s low powered!

      • fartface says:

        Or just get a float valve and never worry about it again as it will self fill the water tank.

        But I like your floating straw idea better. Far more elegant and should have been a part of the design by the coffee maker.

      • john says:

        This is essentially how many old airplanes indicated fuel level.

      • Nova says:

        That looks like a pretty deep reservoir, TBH that idea sounds likely to break off and often get in the way, imagine trying to use this underneath a low clearance cabinet or even in-front where the doors are likely to knock stuff.

        Seeing as how this is already an electronic device, tapping into the mains(with an appropriate form of safety and isolation) would be pretty useful, no batteries to change ever!

  2. greenbacks says:

    Nice and simple, but why stop there. How about adding a solenoid powered tap and have that tripped with the current design.

  3. Katie says:

    Excellent! I have the same espresso machine (and it’s a lovely machine!) and I have the same problem…

  4. Sven says:

    This really does not need to be electrical, you could easily build both a low level indicator and an automatic filler purely mechanical with standard parts.

  5. Fritoeata says:

    I like this! I will try to adapt it for an application that runs low in the reservoir… at work!

  6. henry says:

    Needs more arduino ;) simple setup, appears to work fine.

    I mentioned this in the other thread. If hes going to plumb it, just use a floating ball valve and hot gue it in place. that way the water will always be at a constant level

  7. Bob says:

    Want to make it simpler? Use a transparent water reservoir.

    • Farbro says:

      Simpler vs. easier comes into play, there! The machine pictured has a steel case and an opaque reservoir. Replacing the reservoir with something clear might be one thing but also cutting witness holes or something in the steel casing of the machine… well, a transparent reservoir might be simpler in theory but it’s sometimes *easier* to just make an indicator. :)

  8. echodelta says:

    Although I gave it up (no palpitations) I wouldn’t want stale exposed to air water in a fresh brew. Serve it up fresh, water included. Holding tank designs are for restaurant use where another batch is an hour away, and you’re busy.
    I still have my curb freebee de-poded Melita cone and filter equipped push-button automatic pumper. Pour your cup of water in, get it back moments later minus a little volume. Best cup I ever made. Fresh.

    • Garbz says:

      “Holding tank designs are for restaurant use where another batch is an hour away”

      Ahhh so that’s why every consumer home espresso machine in the world has a holding tank right? ;-)

      Seriously though air contacting water is the least of your problems. Air contacting your beans or your grind on the other hand are far more serious.

      • echodelta says:

        We had a water heater that stank at work. I read in Popular Science that if you turn your water heater up to 147 F. it will kill what causes the blacking stink.
        No more stink. Effing experts telling us to turn down heaters to 120F. sucks.
        But at one time I thought of turning it down to just hot enough to wash hands in right out of the separated faucets, it’s in a warehouse. Glad I didn’t. Legionnaires can grow in that environment.
        Home models follow existing design. Home models don’t get thorough cleaning and disinfecting. We had a home model Bunn at work, I worked on it more than once. Looking back at it …YUCK!
        The next killer bug might come from the filthy area behind the faucet of someone who uses tryclosan type antibacterial soaps on just some of their stuff.
        Standing water bugs me weather it is in the bathroom or kitchen. Classic experiment; tap water in glass open to world, examine under microscope. Time. Bugs and plants.
        Home roasting the ultimate machine for sure.

      • Sven says:

        The home brewers don’t have a holding tank with heated water like the restaurant brewers. They have a tank that’s meant to be filled with cold water and used within a day. If you keep water standing in your coffee brewer for weeks you’re doing it wrong.

  9. ejonesss says:

    “Start a brew without enough water to finish it, and your brew is ruined”

    not only that but depending on the quality of the machine you can even ruin the machine.

    cheap coffee makers lack a sensor that may detect the tank is empty and you may burn up the heating element.

    “It uses tiny amounts of power – the CR2023 coin cell used for power will chemically expire before it is ever actually exhausted”

    you can use a lithium cell witch can have a shelf life of years or even better use a current limiting resistor and you can tap into the main power.

    if the coffee maker is one of the better kind that has a pump built in that pumps the water into a 8 ounce heating element it will have some electronics that you can tap into the 5 volt supply and power the led safer

    http://n8tomlin.blogspot.com/2013/02/keurig-disassembly-pics.html shows the insides of the keurig coffee maker and that tin can with the 2 wires going into it in the first 2 pictures is the heating element and i have scrapped out some similar coffee makers and there are 2 sensors (thermister for controlling the electronics and another that shuts off but resets when it cools + usually some thermal fuse that blows if the others fail).

  10. madwelder says:

    I was born a sight glass man and I will die a sight glass man.

  11. John Avitable says:

    Am I the only one wondering what on earth is going on with the indicator light? I almost feel like there’s got to be some rads getting thrown off on there. Don’t neon indicators do that?

  12. Marc says:

    Rancilio’s Miss Silvia is a great machine, and I might have to set something like this up in my own Miss Silvia. :)

  13. Bredo says:

    It can be simpler, here is my even lower tech version:
    http://p24bredo.wordpress.com/2013/05/13/super-low-tech-water-sensor-for-espresso-machine/

    Miss Silvia is wonderful. She makes great coffee if you know what you are doing (and terrible coffee if you don`t) ;)

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 91,389 other followers