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eering department. , On .the farm, automatic electrical equipment is replacing manpower in dozens of chores. The control devices used in this equipment make possible the substitution of machinery for manpower.
V Controls are available that react to changes in temperature, humidity, pressure time, and light. They can be used to operator heaters, motor driven equipment, lights and other devices ta maintain desired conditions. Thermostats control electric hotbeds, brooders, ventilating systems, sweet potato curing and storage houses. A humidistat responds to changes in relative humidity. It can be used to operate ventilating fans to maintain desired relative humidity, and to control supplemental heaters on crop drying equipment. Pressure switches respond to changes in pressure in liquid, air, or gas. This device automatically controls
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