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)

Final (for now) Bird Bath Heater post

After many redesigns of the heating element I have had no success in melting any ice in the birdbath. I have tested the integrity of the newest element that I made, multiple times, as well as the power coming from the windmill and I can say that the windmill is generating the expected power and the heating element seems to be intact (resistance is unchanged from the calculated and initial measured resistance). It seems that I need either a bigger windmill or even higher gauge (thinner) wire than what I have used so far.

The last heating element I tried was a repeat of the last one only I made it much more compact to concentrate the heat:
Heating Element v3
I put it together using:
I wrapped the Nichrome wire around a short section of wire insulation taken from a hair curler (same one I took the original Nichrome wire from) - I wound the wire as close as I could and then coated it with the RTV silicone. (On the left side of the picture is a tube of RTV silicone (Room Temperature Vulcanizing) meaning it sets and cures at room temperature to become resistant to higher temperatures [this one was rated around 300 degree Celsius)
For clarity, a bigger windmill would mean any of the following or a combination of them:
Larger propeller (bigger swept area)
Bigger motor (larger stepper, treadmill motor – just something with a bigger output)
Higher placement (less turbulent winds)

Other things that would possibly increase effectiveness:
*More efficient heating element
  • thinner wire
  • closer spacing of wire in coil (tighter coil)
  • improve heat conduction from coil to body of element
*Add solar to increase power to heater (likely minimal due to decreased solar radiation in winter)

The windmill itself is undamaged and continu
es to function even after the nasty weather that we've had over the last few weeks. So, I can say the basic design works and I will leave it outside to see how it holds up over the rest of the winter.

I will continue to post over this week to catch up (I've been working on some additional projects)