Tuesday, January 21, 2014

The Other Coffee Maker Hack

Whatever happened to the second hack of the coffee maker?
Well, it went in a few different directions as well, before it finally got put to use.

My initial goal was to use the timer from an old coffee maker to trigger the brew cycle of a newer Single Cup coffee maker (since they have no clocks/timers).
Initially I thought that I would be able to power the timer board independently from the power supply from the coffee maker (there is a ribbon cable connecting the 2 boards together and testing the individual connections enabled me to find the power lines).

Running the board with a 5v power supply seemed to work (I also had to hook a resistor as a load across 2 other lines).

I only have 1 solenoid and it is one that I pulled out of some old broken film camera (I don't remember what it was). The solenoid pulls instead of pushing but I figured that I could still work with that so I make a little circuit with 2N2222 transistor to switch on the solenoid (it needed larger current than the timer board could deliver)– it worked but the solenoid did not deliver enough force to trigger the button. On to another way to solve this issue.

Next I thought I could use the one small servo motor I have (since it is low power and the gearing in it allows it to produce significant force. So, I began putting together a board (circuit came from Make Magazine – link) to run my little servo motor fully in one direction using it to press the button on the other coffee maker and triggering it from a similar transistor switching circuit (I needed to change the base resistor to match the current needed by the new circuit). Testing this is when I found that the clock/timer circuit from the old coffee maker was running fast.
Servo Controller and mini Servo
To keep this short – I realized that I was making everything over complicated and it would be much easier to just use the original coffee maker power supply board and just change out the output of the relay to switch the power on for the servo motor control board. So, I cut the traces from the relay to the mains AC power and connected it to a wall wort dc power supply (I connected the plug, with spade connectors, into the wiring for the wall plug going to the old coffee maker). Finally it all works, just need to mount everything in a box and figure out a way to put the servo by the on button.
Coffee Timer, Finished - prior to putting in enclosure
 This is when my wife, Laura, told me that she ordered a new coffee maker! What do I do with this stuff now? 

Well... she had told me that she wants a better light timer to help her get up in the morning – I've been trying to use a cheap commercial timer (with the rotary dial and tabs to set on and off times) but it hasn't performed well (difficult to get it set correctly to current time and even harder to get it to turn on right when you want it to). They are not made to be very accurate, if they were, then using them as deterrents when you are gone would be ineffective (if they turned on and off at precise times everyday a potential thief watching the house would notice since most people are not so precise when it comes to turning lights on and off everyday). 

Purchasing a timer to switch appliances on and off at specific times is much more expensive than a simple rotary timer. I figured that I already have a digital timer that can switch a relay on and off why not just wire the relay to a regular 3 prong outlet and put everything in together into a box with the display on the front. I did it and it works. Note – the board from this coffee maker turns on for 2 hours and then automatically shuts off.
Fully Functional Light Timer
Total cost:
Coffee maker $0 (old one I still had in storage, Goodwill has them here for about $5)
Outlet for box - $0 salvaged from an old appliance
Outlet cord - re-used from original coffee maker
Project Box (from Radio Shack) about $6
Potential improvements as a Wake Up light:
  • simple circuit to gradually increase the light intensity
  • servo motor to gradually turn light towards the head of the bed (same effect as increasing intensity/brightness)
Some stuff I learned from this project:
  • controlling a servo motor (I've done it before with an Arduino but not from simple hardware - helped greatly in my understanding as to how they function and are controlled)
  • Determining the pinout of cables (I always need practice at this, since it does come up a lot)