Description
Description
The Smart 5V Thermistor Relay Switch – Automatic Temperature Protection is an intelligent, self-contained temperature monitoring and control module designed for automation enthusiasts, hobbyists, and industrial users. Operating on a standard 5V DC supply—compatible with USB power banks, Arduino, Raspberry Pi, and other microcontroller platforms—this module combines a sensitive NTC thermistor temperature sensor with a built-in relay to automatically switch external devices based on ambient temperature .
When the temperature rises above or falls below your preset threshold, the onboard comparator circuit (LM393) instantly energizes or de-energizes the relay, allowing you to control fans, heaters, pumps, alarms, or other AC/DC devices up to 10A. The module features an adjustable potentiometer for setting the temperature trip point, a green LED indicator showing relay status, and both Normally Open (NO) and Normally Closed (NC) output terminals for flexible application design .
Unlike complex programmable controllers, this module works standalone—simply apply 5V power, adjust the potentiometer to your desired trigger temperature, and connect your load. No coding, no microcontrollers, no software required. The onboard comparator provides reliable, noise-immune performance with a built-in flyback diode to protect the circuit from relay coil spikes .
Whether you need to activate an exhaust fan in a hot server room, turn on a heater in a reptile terrarium, protect a 3D printer enclosure from overheating, or automate greenhouse ventilation, the Smart 5V Thermistor Relay Switch delivers plug-and-play temperature protection in a compact, easy-to-use package.
Key Features
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Standalone Operation – No microcontroller or programming required; works immediately after power-up .
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Adjustable Temperature Trip Point – Onboard potentiometer lets you set the exact temperature for relay activation.
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Dual Mode Operation – Use NO (Normally Open) for “turn on when hot” applications, or NC (Normally Closed) for “turn off when hot” applications .
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High-Power Relay – 10A/250V AC or 10A/30V DC contact rating can control fans, heaters, pumps, and more .
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Sensitive NTC Thermistor – Fast response to temperature changes with included external probe.
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LM393 Comparator IC – Provides stable, noise-immune threshold detection.
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Status Indicator LED – Green LED illuminates when relay is energized .
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Flyback Protection Diode – Protects circuitry from voltage spikes when relay de-energizes .
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Compact Form Factor – Small footprint (approx. 50mm x 26mm) fits easily into enclosures .
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Wide Compatibility – Works with 5V USB power, Arduino 5V pin, or any regulated 5V DC supply.
Technical Parameters
| Parameter | Value |
|---|---|
| Operating Voltage | 5V DC (±5%) |
| Operating Current | ≤ 150 mA (relay active) |
| Temperature Sensing Range | -40°C to +100°C (-40°F to +212°F) |
| Adjustable Trip Point Range | Approx. 20°C – 100°C (depending on environment) |
| Relay Contact Rating | 10A / 250V AC or 10A / 30V DC (resistive load) |
| Output Terminals | 3-pin screw terminal (COM, NO, NC) |
| Comparator IC | LM393 (dual voltage comparator) |
| Sensor Type | NTC Thermistor (10KΩ typical at 25°C) |
| Operating Temperature | -40°C to +100°C (module and sensor) |
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