Not including the Android device, you can expect to pay approximately $120 to build the controller and blower that you see here (this includes two Maverick thermometers). The battery I used is ~$40 but you can probably get away with a much cheaper option, especially if you don't plan on running 12-hour cooks.

Android Device

You'll need an Android phone. You do not need a cell or internet connection (unless you want to use the Twitter functionality) but it must have Bluetooth. This app should run on any 2.3.4+ Android device but I can't guarantee it will work until someone tries it. The following platform/OS combos have been tested. If you build one using a different combo let me know and I'll add it.



Device Android OS Version Motorola Droid (original) 2.3.7 Samsung Galaxy S III 4.0.4 Motorola Droid 3 Minimoto v1.7 Samsung Note 3 4.4.2 OnePlus One 4.4.4 Nexus 7 4.4.2

Controller

Part Description Qty URL Price IOIO This is the hardware that links your Android to the blower using Bluetooth. I used an older version of the IOIO but the new one should work fine. The main difference is that you need an adapter (supplied) to connect the Bluetooth dongle. If you don't want to use the new one you can get the older version on ebay. 1 SparkFun $40 Bluetooth dongle The Bluetooth dongles proved to be tempermental. The two dongles linked here work but have a short range. See extended discussion later in this page. 1 Seeed Studio SparkFun $5-10 Maverick ET-73 probes You want at least two probes, one for the pit temperature and one for the food. The pit probe looks different from the food probe so look at the pictures above to get one of each.



Be sure to get ET-73 probes, not ET-732 probes. They have slightly different plugs and are not compatible. 2+, max of 6 Search Amazon and Ebay $10-15 each 2.50mm mono jacks 2.50mm mono female jacks for connecting the thermometers. You need one per thermometer. I bought one jack in a different color to indicate which one is the pit thermometer. Multiple DigiKey

All-Electronics $1 each Standoffs For attaching the IOIO to the enclosure. Any standoffs will do as long as the screws for attaching the IOIO fit through them. 4 All-Electronics $0.40 for 10 3.5mm stereo jack Used to connect power between the IOIO board and the blower. Another one is required for the blower.(listed below) 1 All-Electronics 1*

All-Electronics 2

Digi-Key $1.50 3.5mm male stereo cable Used to connect the IOIO to the blower. A 3' cable is fine. 1 All-Electronics $1.50 2.1MM power jack Double-check to make sure it fits with whatever power supply you buy. 1 All-Electronics

Digi-Key

$1 TIP41C Switching transistor for controlling the blower via PWM. 1 Digi-Key $1 1N4004 diode Protects the IOIO electronics from blower. 1 All-Electronics

Digi-Key $1 #4-40 screws + nuts Attaches the IOIO to the enclosure. Half-inch screws are just barely long enough so longer ones might be good. 4 Local hardware $5 Breadboard I soldered all the components to a breadboard that I bought at a local electronics supply. The one linked to the right should work although you may need to trim it down. 1 All-Electronics $5-10 22.1k ohm resistors One needed for each thermometer. It would be a good idea to get twice as many as needed and measure them with a multimeter. The closer they are to 22.1k ohm the more accurate the measured temperature will be. Don't obsess about it: being off by 100-200 ohms is fine. Multiple All-Electronics

Digi-Key $0.10 each 830 ohm resistor Part of the PWM circuitry. 1 All-Electronics $0.50 Enclosure You can use any enclosure that will hold the IOIO and parts. I used a food storage container from the Container Store. A clear plastic box not only looks cool but lets you see the LEDs to verify that your IOIO is powered and working. Electric project boxes might not work as well--they have slots on the interior that make it harder to install panel-mount components. 1 The Container Store $5 Optional Headers I soldered headers to the IOIO. This allowed the breadboard (with the Arduino headers) to be plugged into the IOIO instead of soldered directly. Digi-Key $2.50 Arduino Headers I used Aurduino headers to connect the circuit board to the IOIO. Arduino headers have a longer pin. This let me replace the circuit board or the IOIO without having to unsolder anything. 1 pkg All-Electronics $1.50 Total price w/ two thermometers (including optional headers) $100-$110



* - The first jack from All-Electronics is the jack I used. However, the second one is probably easier to use.

Power Supply

There are a few options for supplying power:

Battery

Using a battery for power means you can use your controller anywhere, which is convenient. I use a 10 amp-hour sealed lead-acid battery because I want to be able to run the smoker for 10-12 hours. This appears to be much more power than necessary because the battery hardly drained after 8 hours, so you may be able to get by with something cheaper.

Part Description Qty URL Price 12 volt battery 10 amp-hour battery 1 RadioShack

Amazon $25 Battery charger You'll need a charger if you use the battery above. 1 RadioShack

Amazon $11 Alligator clips Alligator clips to connect the cable to the battery leads. 2 (one pair) All-Electronics

Digi-Key $1 Power plug Power plug for connecting battery to the controller. 1 All-Electronics

Digi-Key $1 Rectifier diode (Optional) If you follow my build then it's possible to accidentally reverse the polarity when you hook up the battery, which will fry your IOIO. A rectifying diode will prevent this at the cost of a bit of voltage. A 1-amp diode such as the 1N4007 should do. 1 All-Electronics

Digi-Key $0.50 Total price $40



AC Power adaptor (i.e. wall-wart)

You can buy an AC adaptor but you can probably find one at a thrift shop for cheap. The one I used for testing was a power supply from an old laptop that I bought for 50 cents. You can use any adaptor as long as:

It's 12 volts.

At least 1 amp. More amps is fine. If you want to be overly anal get one that can supply 2 amps. When the blower starts up it will momentarily take more power.

If you still want to buy an adaptor:

Part Description Qty URL Price 12v adaptor 12 volt / 1amp adaptor 1 All-Electronics

Digi-Key $10

Cigarette 12 volt adaptor

One other option is to use a 12-volt adaptor that fits into the cigarette lighter of your car. I haven't tried it but it should work fine.



Blue Tooth Dongle



The IOIO can be persnickety on what dongle it will accept. The IOIO has a dongle page that lists dongles that have been shown to work with the IOIO but it varies by phone and you may have to purchase multiple dongles before you find one that works with your setup. DealExtreme has lots of dongles cheap but they can take 4-5 weeks to ship. The dongles linked in the list above are known to work with the phones I've used.



Class 1 dongles are better because those have a longer range but I haven't found one yet that works. If you do, send me a message so I can try it too.

Blower

These are the parts required for the blower assembly. The nipple that I used fits into the 1/2" ball valve on my smoker. You may have to adapt your blower to fit your smoker.



Part Description Qty URL Price Enclosure Any enclosure that can house the blower and the PCB connection can be used. The one I used is linked here. 1 All-Electronics

Digi-Key $4 3.5mm stereo jack Used to connect the power cable from the controller. Another one is required for the controller. 1 All-Electronics 1*

All-Electronics 2

Digi-Key $1.50 12v blower The blower I used has a tachometer sensor which isn't currently being used. 1 Digi-Key $14 M20 Washer M20 washer. I bought it at a local Ace Hardware. 1 HomeDepot $0.60 Nipple 1/2 x 3 pipe nipple. 1 HomeDepot $2 PVC bushing 3/4 x 1/2 PVC bushing. I had to cut off the end to get it to fit in my enclosure. 1 HomeDepot $0.66 Screws + nuts For attaching the blower to the enclosure. Total price $22

Tools

Drill and bits, preferably a drill press.

If you build a blower like the one above you'll need a drill bit for cutting 7/8" holes, like this one.

Soldering iron and solder.

X-Acto knife or similar.

Wire cutters, pliers, etc.

Not necessary but helpful:

Heat gun and shrink tubing to protect your wiring.

Skills Required

The most difficult skills for this project are soldering and the ability to read simple schematics. You'll likely need some patience, too. :)