Backpack Water Level Monitor for Hydration Packs

The main purpose of the backpack water level monitor is to measure the water level in hydration packs which are normally used by hikers.

When a button is pressed the water level in the reservoir is displayed after the regular measuring of the monitor. The speed of level drops are also kept tracked and an estimate of the number of hours remaining at the present consumption rate is displayed. A beeper will warn the user that the supply is running low if the level drops below a set threshold.

A modified version of the Motorola demo board is used to build the hardware as it contains the MC33794 e-field sensor, MAX232 serial interface, and MC68HC908QY4 MCU. A couple of trace cuts and some added power supply components are all that the board required. A pair of 7-segment displays and 74HC164 shift registers are contained in a separate display unit that mounts at the end of the drinking hose which uses a 3-wire cable to connect to the main unit. The system is being powered by four CR2430 lithium coin cells in series along with a low power voltage regulator supplying 5V.

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