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Jake

Corvo EKG Electric Tea Kettle

What’s The Point of A PID Controller In An Electric Kettle?

By | Coffee, Design

Minimal and modern with a single button and a sleek LCD screen, Stagg EKG and Corvo EKG’s base is hiding something very powerful inside: a PID controller. A proportional-integral-derivative controller is a control loop feedback mechanism widely used in industrial control systems. The PID controller continuously calculates an error value as the difference between a desired setpoint and a measured process variable and applies a correction based on proportional, integral, and derivative terms which give the controller its name.1  Or in much simpler terms, EKG’s PID controller is basically a mathlete with a TI-84 calculator constantly running equations to determine the most efficient way to reach your goal temperature.

“An everyday example is the cruise control on a road vehicle; where external influences such as gradients would cause speed changes, and the driver has the ability to alter the desired set speed. The PID algorithm restores the actual speed to the desired speed in the optimum way, without delay or overshoot, by controlling the power output of the vehicle’s engine.”2 Well before cruise control, the original application of PID controllers was for the automatic steering systems for ships in the early 1920s. So if you ever want to drop an impressive factoid while brewing up a pour-over, you can say your Stagg EKG or Corvo EKG has the same technology as ocean liners.

If your electric kettle has a traditional thermostat, it heats up by overshooting the goal temperature, and then it drops below the goal temperature to cool off. All kettles (that we’re aware of) have a simple on/off controller. So, the power is either at 100% or 0%. Again it overshoots, undershoots, overshoots, and undershoots until it gets close to the goal temperature. Charted on a graph, it would look like spiking zig zag lines or the stock market crashing and rebounding day after day. This is not efficient and in reality, your “hold” is just holding at a degree or two below and above, flipping back and forth.

Now onto the EKG family and the two reasons EKG outperforms everything else on the market. First, Stagg EKG and Corvo EKG use a PID controller (much like your fancy $20,000 espresso machines), so the zig zags are less drastic and resemble a curve leveling off at your goal temperature. This lends itself to a more accurate output. In addition, those other kettles just have on/off mechanical relays (remember from above, either 100% or 0% power). Fellow’s EKG line is able to do a little something called “Pulse Width Modulation” using a non-mechanical approach. PWM uses series of on/off pulses to vary the duty cycle, the fraction of time that the output voltage is “on” compared to when it is “off.” This PWM action allows us to maintain temp much more accurate compared to a standard mechanical relay that is clicking on and off around the set point. Oh, and that also means Stagg EKG doesn’t have that annoying mechanical on/off click that drives baristas crazy.

Okay okay… so what does this mean in terms of actual performance? After running countless tests, we can say with confidence that the EKG family’s PID controller heats and maintains water temperature to +/- .3 degrees Celsius. This is three to four times more accurate than the leading electric pour-over kettle available on the market today. In one series of tests, we compared Stagg EKG to the leading variable temp pour-over kettle (to be nice, we won’t name names).

The test: 600 ml of water set to hold at 200°F.

Although both kettles have an average temperature of essentially 200°F over the course of testing duration (averages can be misleading), the standard deviations tell a very different story. Stagg EKG has a standard deviation of 0.27°F while the leading pour-over kettle comes in at 1.06°F.

As you can see from the plot, Stagg EKG is bouncing between about 199.5°F and 200.5°F (blue line), while the leading pour-over kettle ranges from a low of below 198°F and a high of over 201.5°F (red line). The competitor kettle turns on (100%) overshoots the set point, then shuts off (0%). The water cools down to 198°F and then the kettle clicks back on (100%). The result is relatively drastic swings in temperature even though you’re technically in hold mold. Stagg EKG, through PID and PWM is able to do micro adjustments that make it hold temp three times more accurate in this experiment.

Stagg EKG vs. Leading Variable Temp Pour-Over KettleWhy should the inner-workings of an electric kettle matter to you? The fourth wave of coffee has been forecasted as “the science of coffee.” As we learn more about coffee, users seek more resolution on their brewing parameters as seen in many third wave shops employing techniques such as Total Dissolved Solids, brewing by weight, and using coffee brewing smart technology. Stagg EKG and Corvo EKG provide users the ability to manipulate temperatures with to-the-degree precision to easily control the brewing temperature. This empowers users to experiment and explore all the varying degrees of extraction for coffee and tea. Both Stagg EKG and now our latest product, Corvo EKG, have a brew range of 104°F to 212°F (40°C-100°), can hold the set temperature for 60 minutes, and most importantly, are the most accurate variable temperature electric kettles on the market.

Corvo EKG Electric Tea KettleStagg EKG Electric Pour-Over Kettle

 

 

 

 

 

 

 

 

 

Master Brew Class with Dylan Siemens US Brewers Cup Champion

Master Brew Class With Dylan Siemens | Onyx X Fellow

By | Bay Area, Coffee

The Fellow Playground had the honor of hosting Dylan Siemens, the 2017 US Brewers Cup Champion, for our #OnyxXFellow Brew Master Class Weekend. Not only does Dylan bust out incredible cups of coffee, he couldn’t be a nicer human being. The Fellow team didn’t want our new Arkansas friends to leave. While the weekend was jam-packed with activities, by far the best part was watching Dylan in action teach brew classes. The level of his knowledge is mindblowing, and we were like kids in a coffee-infused candy listening to his tidbits and sipping on his brews.

For Dylan’s Master Brew Classes in the Playground, he came up with three different recipes using the Stagg EKG Electric Pour-Over Kettle, Stagg [X] Dripper, and Stagg Double Wall Carafe. Follow along with his method below, and then let us know how your brews turn out! Read More

Stagg EKG+ Production Update: It’s Go Time!

By | Design

Be honest. You’ve seen seen Stagg EKG on Instagram feeds for the past three months, shaken a fist at the screen, and said, “Grrrr…Fellow, where’s my EKG+?” Trust us, the EKG+ delay stung— we wanted to ship it out just as badly as you wanted to receive it. Unfortunately, the last checkboxes to be checked came down to safety regulations, and they were out of our control. Sometimes we wanted to shake our fist at the screen and say, “Grrr…safety, who needs you?” But alas, we drank a cup of coffee, calmed down, and realized safety is very much needed.

We spent the holidays away from home and our families in China and Taiwan to ensure we were making progress every single day. I was there for 10 days at the end of December while our other engineer, Neil, spent seven days in the factory in early December. The first hold-up we were working through was a product modification for the EKG+ to pass the safety certification. This was the addition of an “enable/disable” feature for Bluetooth as required for ETL product certification by Intertek (the governing body for electronic product safety). We’re happy to say this feature was recently completed (thankfully achieved through a menu in software and not as an additional switch), and EKG+ was re-submitted for ETL certification. Read More

WHY DOUBLE WALL INSULATION?

By | Coffee, Design


Here at Fellow, we obsess over temperature and understand how important it is for brewing coffee. That’s why we created two pour-over drippers, Stagg [X] and Stagg [XF] with vacuum insulated double wall stainless steel to help reduce temperature loss during your brew. Obsessive? Yes. Excessive? No.

The thinking: the more control you have over temperature, the more control you have over your extraction.

But how does our double wall insulated stainless steel dripper actually stack up to competing drippers? We’ve run a series of tests comparing Stagg [XF] Dripper to other popular coffee drippers. For the sake of consistency and accuracy, we focused on testing Stagg [XF] versus flat bottom single wall stainless steel drippers. Here’s what we found:

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How To Dial-In Your Prismo To Pull The Best “Shot”

By | Coffee

Just like a real espresso machine, Prismo needs a bit of “dialing in” to pull a great shot. When done correctly, Prismo makes an incredibly flavorful, dense, and tasty espresso-style brew. When done wrong, like with an espresso machine, you can produce sub-optimal results like sour taste notes and a grainy texture. It takes a few brews to settle into your favorite routine, but once you find that sweet spot, Prismo can pull tasty espresso-style coffee shot after shot.

Wondering how to make the best possible shot with Prismo? Here are a few tips and tricks we’ve learned from product testing and from our friends in the coffee world…

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EKG+ Production Update

By | Coffee, Design

 

Hello Fellow pre-order supporters!

As you’ve likely seen, we have started to ship Stagg EKG units (the non-BlueTooth version) to Kickstarter Backers. As you know, the EKG+ units were not in the same container. Although we did expect about a month difference between the two units, we didn’t forecast many of the challenges we’re currently facing.

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Prismo: Superpowers for your AeroPress®

By | Coffee, Design

 


Meet Prismo, an AeroPress® attachment that unlocks espresso-style coffee without an espresso machine.

We here at Fellow love espresso, but sometimes we don’t have access to a good espresso machine, and the team is left to walk to the nearest coffee shop. Since we’re a coffee product company (and that coffee shop is over a mile away), we figured we should probably solve this problem. Read More

The Anatomy of an “Espresso-style” shot

By | Coffee


So when you pull a shot with Prismo, why call it “espresso-style” instead of just an espresso shot? Well friends, a leopard can’t change its spots. Although Prismo makes a pretty damn tasty shot, it lacks some of the features that make up a tried and true espresso shot. The magic of a traditional espresso comes with 9 bar pressure, 25-30 seconds of percolation time, and the right amount of  heat. All of which are difficult to achieve when manually pressing a shot.

That said, we love the espresso-style shots we’ve made with Prismo! And hey, for a much lower price point than an espresso machine, you can get close and have fun doing so. So what is “espresso-style”? Let’s break it down:

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Crowdsourcing Design: Kickstarter Stretch Goals

By | Uncategorized

Since Duo Coffee Steeper’s Kickstarter campaign back in 2014, we’ve tried to keep our backers and fans involved as much as possible in our design process. From Duo to Stagg System, we often send out surveys and invitations to participate in user testing on new products. For our second round on Kickstarter with Stagg EKG our mentality has been no different.

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