That said... Essentially, this is a guide for making a data logging system for use with the breathalyzer microphone.
To accomplish this, an Arduino and a Logomatic SD data logger are embedded into an old and considerably large tape deck. The data is fed into the tape deck through an unassuming 1/4" audio jack.
Step 1: Go get stuff
- old tape deck or similar
- Arduino Diecimilia
- Logomatic V1.0 SD Data Logger (available from Sparkfun)
- SD card
- An SD card reader
- A 10K resistor
- A schotky diode
- 1/4" jack (unless you already got one fo the breathalyzer mic)
- 9V battery connector
- 9V battery
- hookup wire
- electrical tape
- philips head screwdriver
- soldering setup
- pliers and/or cutters
- power drill
Step 2: Prep the case
I decided that the best place to insert my electronics was in the battery slot of the tape player. Unfortunately, the battery slot was just slightly not deep enough for the Arduino. This was easily resolved by disassembling the case, breaking off some excess plastic and reassembling.
Once the plastic was broken, everything fit in with room to spare.
The only real rule with this is that there needs to be enough room to comfortably fit all of your parts inside. Don't forget to factor in a reasonable place for mounting the 1/4" stereo jack without creating too many problems.
Step 3: Insert the stereo plug
In my case, I didn't have to drill a hole. I was able to pass it through an existing hole in the case and secure it that way.
Step 4: Prepare the SD card
Step 5: Setup the Logomatic
Wait for a few minutes. You should see a flashing sequence of lights. When the lights are done flashing, remove the card and put back into card reader.
Two text files should appear called ___ and ____. You want to open them and configure it to have the following settings ______
Step 6: Build the interface circuit
Step 7: Program the Arduino
In other words, download this code. Download the Arduino development platform. Load this code into the Arduino development platform. Once the code is loaded, hit the upload button as shown in the picture below.
That's about it.