Slide show


A researcher wanted a small inexpensive data logger to record water temperature in streams. One of the problems encountered in research projects is having the measurement devices stolen or moved from the desired position. A package was needed for the recorder that would be waterproof and inconspicuous.


The data logger circuit consisted of a low power microprocessor, a temperature measurement IC, several serial non-volatile memory ICs and a voltage regulator. An inductive communications coil allowed the processor to be programmed and data to be retrieved.

The solution to make the device inconspicuous was to embed the circuit in a rock-shaped molded urethane package. We found a rock that was large enough to contain the circuitry and used it to make a mold. This also provided a waterproof enclosure for the circuit. We mixed sand into the urethane to produce a convincing rock appearance.


We produced a small number of these units.