Introduction: Smart-home Enabled Single-cup Coffee Maker
I have this great coffee maker. It makes one travel cup, and that's all I want on my way out in the morning. However, to start the brew cycle it requires the push of a button. This characteristic prohibits it from working with a timer or any smart-home switches.
The easy solution would be to buy a cheap full pot brewer with an on/off switch, but I do not want a full pot brewer. Apparently the product I want does not exist in the market- so here we are.
My morning routine would start with me heading to the kitchen to start the coffee maker, then going about the normal morning business. I really wanted to be able to use my smart-home device to start my coffee without me going to the kitchen first.
Now, As long as I remember to fill the water and the grounds before bed, I have hot coffee waiting for me when I get to the kitchen.
This mod cost about $12 (excluding the materials I had on hand: coffee-maker, 5vDC transformer, soldering and wiring supplies, smart-home enabled outlet).
Basic knowledge of electricity, electronics, soldering.
A coffee-maker you want to make smart enabled- and feel comfortable disassembling with the confidence you can get it reassembled. If you have this exact maker feel free to contact me for more specifics on disassembly before you start!
* I wouldn't attempt this with a K-brand maker, only a maker that has a single momentary push-button switch to initiate the brew cycle.
Smart-home device, or plug-in timer.
5vDC transformer (old usb phone charger)
Programmable Relay (ordered from Amazon)
Soldering Iron, Solder, Wire cutters, Screwdrivers,
Double-sided mounting tape.
Wire: copper, stranded, insulated, 18-20 gauge (Note- Specific colors of wires are mentioned in this instructable because it made it easier to write the descriptions for this instructable. You can use any colors you want. :) ).
Step 1: Assembly
I disassembled the maker and used my multimeter to get an understanding of how the maker works. This photo shows the maker with the new components connected.
I found that the coffee-maker's circuit would accept a push-button hold-down time of as much as 40 seconds, but it only needs about a quarter second to activate. If the hold-down is longer than 40 seconds it will default the maker to off.
Although I found 5 volts in the circuit, I also found it didn't have enough amperage to trigger the relay, so I determined I would need to provide a separate low voltage power supply to drive the relay.
I obtained a 5 volt DC transformer from a USB phone charger by carefully removing the transformer from the plastic housing.
The wiring diagram is found in the next step of this instructable.
Step 2: Wiring
I soldered 2 wires (green and white) directly to the coffee-maker's incoming 110vAC on the main circuit board and soldered those wires to the 110vAC side of the transformer circuit board.
I soldered two wires (red and black) to the 5vDC contacts on the transformer circuit board and connected them to the screw terminals on the programmable relay.
I jumpered the 5vDC + to the Signal+ terminal, and the 5vDC- to the Signal -.
When 110vAC is applied the relay is triggered.
I connected two wires (brown and blue) to the Normally Open (NO) and the Common (COM) screw terminals of the programmable relay, and soldered these wires to the contacts of the brew-start switch circuit board.
Step 3: Programmable Relay
I purchased the programmable relay on Amazon, it cost about $12.
The programmable relay is programmed to wait 1.5 seconds before closing the relay for .5 second. For my maker this works as intended. I found that a short delay to start was needed to ensure consistent triggering.
Step 4: Fitting the Components Inside the Case
After testing that everything worked, I mounted the components inside the coffee-maker case with double-sided foam mounting tape, taking extra care to ensure all wiring is secured well clear of the heating chamber.
Step 5: Control
Now when the 110vAC is applied, the relay is triggered which closes the push-button circuit and starts the brew cycle.
This maker has a feature that shuts off the AC when the water reservoir is empty, so I did not need to devise any other methods of shutting the brewer off, however as an added safety measure I also program the smart-home device to shut off after 3 minutes.
This project will work with either a smart-home controller, a remote-controlled plug, or a simple timer. It also retains the ability to function as-original with the push of the button (as long as the outlet it is plugged in to is on).
The only peculiar behavior is that if the maker has been unplugged, it will trigger the relay when it is plugged back in. This isn't a serious issue, if there is no water this particular maker will turn itself off, or you can manually stop the cycle by pushing the button.