Control a small DC fan from a temperature threshold with a transistor or MOSFET, flyback protection, and hysteresis; this is not an AC-unit controller.
Engineering approach
Control a small DC fan from a temperature threshold with a transistor or MOSFET, flyback protection, and hysteresis; this is not an AC-unit controller.
Implementation guidance
Drive the fan with a logic-level MOSFET or rated transistor, add a flyback diode, use a separate load supply when needed, and apply different ON and OFF thresholds so sensor noise cannot chatter the output.
Scope and limitations
DHT11 is slow and modestly accurate, and this prototype cannot control refrigeration, HVAC contactors, or mains equipment. Use approved thermostatic controls and qualified installation for those systems.
Choose the required components and verify their specifications in the Juthour Tech store.
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