Vehicle Frost Box
The system I choose to research is a simple "open-looped system" called the "Vehicle Frost Box". This system is used to informing motor vehicle operators that likely conditions for icy roads are developing. Black ice cannot be seen and is a prime contributor to vehicle accidents during the winter months. If used, this simple system could actually save precious time, money and physical injury.
For system development, the "Problem Statement" is; "Black ice cannot be seen on roads, causing safety hazards for drivers." Next, the "Need Statement" is; "We need a way to determine when favorable weather conditions exist to form black ice on roads". Last, the "Requirement Statement" consists of the following: the system must be cheep, reliable, and linear, with a low thermal mass allowing a quick response to variation in air temperature.
There is a system already in use that is cheep. This system uses a liquid crystal strip attached to the drivers wing mirror. However, this attachment location is too high from the ground to properly determine road conditions. Additionally, some cars have heated mirrors, which would render this system useless.
A silicone semiconductor junction, in the shape of a diode was chosen to build the design around. This option filled all the requirements listed in the "Requirement Statement". Optional sensor devices were thermistors, thermometers, and thermocouples. These options were discarded because of high cost.
The basic design of the frost box follows:
Powered by vehicle ignition
Uses a remote temperature sensor mounted close to the road surface
Display is a single tri-color Light Emitting Diode (LED)
Mounted on the driv...
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...to determine length for the wires that connect the system. Care must be taken to insure the wire path is protected from fraying, corrosive conditions and moving vehicle parts.
Now that the Frost Box is installed and operational, the operator will be able to determine black ice conditions. The primary application for the Frost Box is installation on motor vehicles. Another application for the Frost Box is installation in green houses, to determine when heating should be turned on.
I found this system interesting to report on. Not only because of its simple design, but because my husband constantly warns me to be careful during the inclement winter weather here in Ohio. I hope you found it interesting too.
Dellow, Steve, "Everyday Practical Electronics/ETI" January 2000: "Vehical Frost Box", Wimborne Publishing Ltd. 1999