PICAXE Pitcher Perfect Thermometer

Sometimes, silly seems to work.  I was finishing the software for a digital thermometer with all of the pieces on the workbench and it occurred to me that I had not even given any consideration to an enclosure.  This is unusual for me since I generally order a project box, plastic or aluminum, when I order parts.  Maybe my friends are correct and it is just Mr. Old Age creeping up on me, but as long as I can remember to unplug my soldering iron, I'm not going to dwell on the issue!

I continued with coding.  Yesterday I found myself in Wal-Mart and I was looking for a cutting board in the kitchenware section (to use for a base of a Morse Code Key.)  And there it was, the perfect enclosure for the perfect price, under $2.  So, sit back boys and girls and lets build the pitcher perfect kitchen thermometer... build it for a gift, build it for your mother, or build it for yourself and be the envy of your neighbors.

Step 1 Getting it all together

This is a PICAXE microcontroller, uC, project which means the code is written in PICAXE Basic.  There are several places on the Internet to acquire the parts, but the places listed below are the suppliers I used and have used repeatedly without issue.  Consistently good service is one of the things I think about and I put this before being thrifty to extremes.  For example, I have been waiting for a few parts from mainland China... since July!  (I do believe there really are slow boats...)  On the other hand, I ordered some parts Monday from phanderson.com and received them today, two days later.  Do what you need to do to stay within your budget, but even if you have to buy everything, you are in the sub-$20 range (of course, you may have to pay a little more because of minimum quantities and shipping but you will have some parts left-over for another project.)

Bill Of Materials:
Item                   Long Description                  Suggested Source                                        Note

• PICAXE             PICAXE-08M2 (8-pin DIP)    http://www.phanderson.com/picaxe/
• Thermistor       10K neg temp coeff               http://www.phanderson.com/picaxe/picaxe_thermistor.html
• Protoboard*       AXE021 - PICAXE-08 Kit      http://www.phanderson.com/picaxe/         ONLY for PC with SERIAL PORT
• Protoboard*       PICAXE USB Protoboard     http://www.phanderson.com/picaxe/         NEEDED only for USB chip programming
• 6V battery          6V Lantern Carbon/Zinc      Harbor Freight / Wal-Mart / Sporting Center
• 7805                  5V voltage regulator              http://www.radioshack.com/product/index.jsp?productId=2062599
• 470uF cap        Electrolytic capacitor             http://www.radioshack.com/product/index.jsp?productId=2103624    (see text)
• 100nF cap        ceramic or polyester             Comes with phanderson's protoboards or procure from Radio Shack
• 10K x 2               1/4W resistors 5%               http://www.radioshack.com/product/index.jsp?productId=2062347
• 22K                      1/4W resistor 5 %               http://www.radioshack.com/product/index.jsp?productId=2062331
• LCD**                 Dual 2 line x 16 character     http://www.ebay.com/itm/Lcd-Display-16-x-4-Lines-Serial-Cable-Micro-/350219967924?pt=LH_DefaultDomain_0&hash=item518abc9db4
• Pitcher 1G       MainStays 1 Gallon                 Wal-Mart 73149-49009 about $2
• Misc                 Wire, solder, hobby knife, soldering pencil

* If you purchase your PICAXE chip from phanderson.com it will come with one 22K and one 10K resistor.  If you purchase the serial port protoboard, it will come with one 22K and one 10K resistor, an IC socket, and the small bypass capacitor.  If you purchase the USB protoboard and programmer, it too will come with the 22K and 10K resistor.  Please note that if you intend on using the USB programmer you will still need to purchase the AXE021 protoboard or you will have to utilize some other protoboard for circuit construction and inclusion in the project or purchase something like this: http://www.sparkfun.com/products/9260

If you do not wish enclose the project as shown, then only one of the protoboard is required.  I used one of these: http://store.fungizmos.com/index.php?main_page=product_info&products_id=189&zenid=4a48db672a7555696946b3443533d84d

** You will need to use a solder pencil and some solder-wicking braid or vacuum sucker to remove a solder pad on the LCD as described in the LCD description on eBay: "...remove the solder from J3 then it is 4800 8N1"  The PICAXE code requires this modification!  I have, using modified code, used both a SparkFun 9600 Baud and a Scott Edwards 9600 Baud display, both 2-line x 16-characters.