Discreet Data Logger

There is no better way to hide a covert device than to stick it inside a larger conspicuous device.

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

To do this, you will need...

materials:
- 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
- PCB
- hookup wire
- electrical tape

tools:
- philips head screwdriver
- soldering setup
- pliers and/or cutters
- power drill

Comments

[beehard44]

i was thinking of an analog datalogger using the tape...

[timmy1234s]

so what value of the diode do you get!?!?

[Derin]

doesnt matter

[timmy1234s]

also, what type of 10k resistor do you get ? Is it the one with 1/8 watt, 1/4 watt, or 1/2 watt?

[Derin]

any of those should work

[tyeo098]

What exactly is it logging?

[randofo]

In this case, breathalyzer data. But, it can be modified to log any analog sensor.

[vatosupreme]

could you use it to log position data from an incremental position encoder? (like on a cnc)

[randofo]

I don't see why not. I actually didn't make the datalogger itself. I bought it from here:

http://www.sparkfun.com/commerce/product_info.php?products_id=752

They have full documentation. You should be able to log most anything so long as you want it on an SD card.

[merseyless]

Quote "Two text files should appear called _ and . You want to open them and configure it to have the following settings " somthing is WRONG with what is NOT in this sentence. What are the settings?!?

[randofo]

Oh yeah... I forgot to finish that. Basically, you want to open the text file and keep the default settings for serial communication. Sparkfun has documentation about configuring the datalogger on their site. I'll fix that tomorrow.

[merseyless]

thx

[ongissim]

It would be cool to use an open PWM pin of the Arduino and hook it up to the input of a VCO, and connect the output of the VCO to the taping mechanism in the recorder so you can tell how much someone is intoxicated by the pitch of the tone.

[mothflavour2]

it would be cool if it could log data onto the tape itself. I'm considering doing a bit of research into converting a VCR to store data on VHS tapes. Nice instructable.