For my monthly maker column in Dutch newspaper “De Volkskrant”, I made a coolbox in which you can control the temperature in three separate compartments to keep craft beer at just the right temperature.
The contraption I build uses three Peltier-elements to cool, an old desktop computers power source, an LCD to show both the measured and the set temperature and finally an Arduino to tie it all together.
Step 1: Materials and tools
- a coolbox. Mine was 40 x 15 x 30 cm
The active cooling part:
- three Peltier elements. I used 40 x 40 mm ones from Conrad: http://www.conrad.com/ce/en/product/189115/TEC1-12…
- three large heat sinks, including fans
- three small heat sinks, no larger than 40 x 40 mm.
- three thick pieces of thermally well conducting metal. I use aluminium. as thick as the lid of the coolbox and no larger than the Peltier elements.
- three power MOSFET’s: IRF3205 (http://www.irf.com/product-info/datasheets/data/ir…
- a power source that can dish out 12V (or 15V, even better), 16A. I use an old desktop computers power source and will assume you do as well for the rest of this instructable. If you choose a different power source, I assume you know enough about volts, amps and watts to calculate if your source of choice will work.
The micro-electronics to control it all:
- three temperature sensors. I used the often used tmp36 and this instructable assumes you do as well. However, if you have calibrated thermistors, I suggest you use those. Arduino’s and multiple tmp36’s often cause problems with stable temperature measurements that you do not experience when only a single sensor is used on the Arduino.
- an 16 x 8 LCD screen. If you have the Arduino starter-kit: it’s the one supplied in that kit. If you have never used the LCD screen with an Arduino before, either use the examples in the Arduino starter kit, or this excellent instructable: http://www.instructables.com/id/Connecting-an-LCD-…
- 4 10 kOhm potentiometers. (higher resistance no problem)
- 10 kOhm resistor
- breadboard and assorted wires
For more detail: Temperature controlled coolbox