Friday, March 25, 2011

I Drink the Beer I Make

Time and temperature are two important parameters that are monitored during the brewing process. I developed a device that times the various brewing steps and where applicable monitors the temperature.

Here is a list of the available functions:
  • Brew – Starts a timer showing time for the overall brewing process. It also displays the current battery voltage and display a warning if the voltage is getting low.
  • Strike – Displays the temperature as the strike water is heated. It also displays the temperature rate of change so the end time can be predicted.
  • Mash – Tracks the time and temperature during the mashing process. A warning will be displayed and an alarm sounded if the temperature falls outside the minimum and maximum allowed range.
  • Sparge – Similar to the mashing function.
  • Boil – Tracks the time during the boiling process. An alarm is sounded for each of the hop additions.
  • Chill – Monitors the wort temperature as it is cooled and sounds an alarm when it reaches the desired temperature.
  • Alarm Toggle – This will enable or disable the alarm sound.
  •  Display Backlight – This will turn on or turn off the display backlight.
  •  Defaults – These are the tunable parameters such as minimum temperature and maximum temperature, mash, sparge and boil times, etc.
I used the Pololu SVP-324 for the hardware platform. The SVP makes a good general purpose project platform. The SVP has all of the needed hardware for this project except the temperature probe.

Here is a list of the hardware functions I used. There are many more features available such as motor controllers, multiple digital inputs and outputs, servo control lines and two regulated power supplies one of which is adjustable.
  • ATmega324PA AVR microcontroller (32 KB flash,2 KB RAM, 1 KB EEPROM)
  • 16x2 LCD display with backlight
  • Three Buttons
  •  Buzzer
  • One of the eight analog inputs

The temperature probe was constructed using a two foot long piece of copper tubing and a TMP36 temperature sensor. The copper tubing is the type used to run a water line to a refrigerator ice maker. The TMP36 fits perfectly inside the tube.

The steps to make the temperature probe:

·         Straighten the desired length of copper tubing.
·         Crimp one end and seal it with a non-lead based solder.
·         Use heat shrink tubing for each lead to insulate each lead soldered to the each of the three wires.
·         Insert the sensor and wire into the open end of the tube until it hits the bottom.
·         Seal the opened end with silicon sealant. This end should not be submersed in the liquid.
·         Wrap this end with a thermal insulation material such as foam or vinyl tubing so the probe can be handled safely when removing it from a hot liquid.

At some point I will decide on a water resistant case for my BrewMon project. For now I am just using a plastic baggie.

Here is the code:

Enjoy and if you are ever in the area visit Keystone Homebrew Supply.

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