The finished controller

GitHub and KC Ver. 1.01

I started a GitHub repository for my source code.

All night test - Complete!

I finally got the thermostat working. I added a delay to the relay loop that makes it wait ~ 3 minutes before shutting off the relay and ~ 3 minutes before turning on the relay.

This keeps the relay/freezer from thrashing (turning on and off rapidly) when the temperature is on the cusp. I ran it all night with the set temp at 50° when I got up this morning the current temp was 48° FTW!

I’m going to lengthen the delay a little bit and add 1° to the upward set temp so it stays off longer on the temperature rise and gives a bigger compressor rest zone between runs.

Pictures and source code to follow.

IT'S DONE! -- Sort of...

The boarduino came Saturday. It took me about 10 minutes to assemble with these instructions: http://www.ladyada.net/make/boarduino/solder.html

I uncharacteristically did not take pictures. The above instructions illustrate the process better than I could.

I soldered all the connections to the peripherals and added connections to the high voltage box. I put it all together, updated the programming and plugged it it. It was a complete success... until... it cooled down to the set temp and began thrashing. The temp flickered back and forth between 51 degrees and 49 degrees about twice a second. The relay was clicking back and forth like a buzzer.

I pulled it out of service and I am working on a way to delay the cycling. My goal is to make it stay on for an extra 10 minutes to allow the temperature to "latch" and stay off on the way up for the same reason.

Waiting on parts

I ordered a "brain" for my controller. I'm getting a boarduino http://www.hvwtech.com/products_view.asp?ProductID=661 from solarobotics.
This will let me permanently solder the *duino in place. Once it arrives, I'll be minutes from being done.

Making the temperature probe

I'm making the temperature probe to go in the main body of the freezer out of

• 4 feet of cat 5 cable
• 1 LM-34 temp sensor
• 1 3 inch length of 3/8 inch copper tube
• Electrical tape
• JB Weld

I started by unjacketing the cat 5 and untwisting one pair (orange). I then retwisted the solid orange onto the blue - blue/white pair.

Next I soldered the wires to the legs of the LM-34 and TESTED it. I've built stuff like this in the past and not tested it before I commited to making it a permanent installation. Bad idea.

Then I wrapped the legs in electrical tape and dry fitted it in the tube

Next I mixed up some JB weld and slathered it over the sensor and pulled it back into the tube. I then scooped more JB weld into the end of the tube, taped both ends and hung it up to set overnight. I'll fill the tube completely in the morning with thinned JB weld and then let it rest 24 hours before I'll deem it "ready."

The kegerator code so far

This is a work in progress:

/*

Kegerator Controller by Chuck McKenna

is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License

The circuit:

* LCD RS pin to digital pin 12

* LCD Enable pin to digital pin 11

* LCD D4 pin to digital pin 5

* LCD D5 pin to digital pin 4

* LCD D6 pin to digital pin 3

* LCD D7 pin to digital pin 2

* LCD pin 1 to ground

* LCD pin 2 to +5v

* LCD pin 3 to 4.7K ohm res to ground

* LM-34 Vout pin to Analog 0

* Button up to digital pin 7

* Button down to digital pin 8

*/

// include the library code:

#include

// initialize the library with the numbers of the interface pins

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

// set pin numbers:

const int buttonUpPin = 7; // the number of the Temp Up pin

const int buttonDnPin = 8; // the number of the Temp Down pin

const int tempPin = 0; // analog temp sensor pin

// variables:

int setTemp = 50; // variable storing the Set temp

int currTemp = 0; // variable storing the actual, current temp

int tempTemp = 0; // temporary temp

int buttonUpState = 0; // variable for reading the pushbutton status

int buttonDnState = 0; // variable for reading the pushbutton status

int tempIn = 0; // get temperature variable

void setup() {

// set up the LCD's number of rows and columns:

lcd.begin(16, 2);

// initialize the pushbutton pins as input:

pinMode(buttonUpPin, INPUT);

pinMode(buttonDnPin, INPUT);

lcd.setCursor(0, 0);

lcd.print(" Key Largo");

lcd.setCursor(0, 1);

lcd.print(" Brewery");

delay(2500);

lcd.setCursor(0, 1);

lcd.print(" ");

}

void loop() {

// Print header line of output

lcd.setCursor(0, 0);

lcd.print(" Current | Set ");

// set the cursor to column 0, line 1

// (note: line 1 is the second row, since counting begins with 0):

lcd.setCursor(3, 1);

lcd.print(currTemp);

lcd.print("F ");

lcd.setCursor(9, 1);

lcd.print("|");

lcd.setCursor(11, 1);

// Check buttons for set temp

buttonUpState = digitalRead(buttonUpPin);

if (buttonUpState == HIGH) {

// add 1 to setTemp

setTemp++;

delay(250);

}

buttonDnState = digitalRead(buttonDnPin);

if (buttonDnState == HIGH) {

// subtr 1 from setTemp

setTemp--;

delay(250);

}

lcd.print(setTemp);

lcd.print("F ");

//Get the temp

tempIn = analogRead(tempPin)/8.0;

currTemp = (tempIn * 9)/ 5 + 32; // converts to fahrenheit

tempTemp = setTemp-1;

//Psuedo Relay

if (tempTemp > currTemp) {

// turn off relays

lcd.setCursor(15, 1);

lcd.print("-");

}

if (setTemp <>

// turn on relays

lcd.setCursor(15, 1);

lcd.print("+");

}

}

Some photos