We worked on a version of thermal fishing bob described here:

http://publiclab.org/wiki/thermal-fishing-bob

We found there were problems with the circuit diagram shown in this wiki page.

This version uses a 10K Thermistor from Ada Fruit:

http://www.adafruit.com/products/372 It comes with a 1% 10K resistor which you can use as calibration or for a resistor divider

Additional parts: * 1 common-anode RGB LED * wire * a breadboard or circuit board & soldering eqmt. * Arduino * 9v battery and holder

Here is our first draft of the circuit board:

Following the excellent Ada Fruit instructions changed the board to stabilize the voltage through the circuit:

Here is the arduino sketch:

We had some successful tests:

The circuit inside its repurposed Kool-Aid enclosure.

We stabilized it with styrofoam cups.

And deployed it in the bathtub.