Introduction
   In areas where ambient temperatures reach in the high 80 degrees Fahrenheit, such as Central America, South America, Asia, the Middle East, and certain areas in the United States, a portable fan would help. It may seem challenging to those new to the world of analog circuits and analog circuit design to conceptualize a solution using fundamental circuits and ICs; however, the following provides a step-by-step implementation of a basic temperature-based fan thermostat/controller. This approach makes use of the popular USB port available in many portable devices to create a USB-powered fan thermostat/controller that can bring relief to the user. By using a simple temperature sensor coupled with a simple low power circuit that consists of the TS6001-2.5 voltage reference, the TS1001 low power operational amplifier, and the TS9001 comparator, you may find the design of a 5V USB-powered fan thermostat/controller to be easy, interesting, and useful.