Thermistors, NTC Temperature Probes and PTC Components
Thermistors and temperature-dependent components
A thermistor is a resistor whose resistance changes substantially with temperature. This collection includes bare NTC and PTC components, wired NTC temperature probes, thin-film and SMD sensors, NTC inrush-current limiters, PTC heating and protection parts, plus temperature-control and data-acquisition modules. These are different electrical and mechanical products, not universal replacements for one another.
Understand the product families
- NTC sensing thermistors: bare bead, epoxy-coated MF52-type, MF5B thin-film and SMD parts are offered in selected resistance, B-value, tolerance and package options. NTC resistance falls as temperature rises. R25 is the nominal resistance at 25°C; 10 kΩ R25 alone does not establish the same temperature curve as another 10 kΩ part. B3435, B3950 and B4250 options require the controller's matching calibration.
- Wired NTC probes: cylindrical metal heads, air and surface probes, magnetic mounting, M4/M6/M8 threaded heads, waterproof-style sheaths and XH2.54 two-pin cable options serve different installation points. Confirm sensor type and curve, probe head dimensions, lead length, connector polarity/pin assignment where relevant, ingress and temperature limits of the whole assembly. A listing's “waterproof” or “high temperature” wording does not certify every selected cable or connector for immersion or extreme heat.
- NTC inrush limiters: disk types identified by part series and cold resistance limit power-on surge by self-heating. Select by steady-state current, energy rating, cold resistance, hot resistance, cool-down/restart behavior and enclosure temperature. A 10 Ω inrush disk is not a 10 kΩ sensing probe.
- PTC devices: positive-temperature-coefficient sensors, self-regulating heater elements, motor-temperature protection parts and resettable protection devices have distinct trip, hold, voltage, current and thermal behaviors. A PTC heater is not a drop-in NTC sensor; a thermal switch and an electronic PTC element are not automatically interchangeable.
- Measurement modules and other sensor technologies: RS485/Modbus multi-channel readers, fan controllers and temperature-switch boards require their specified probe type, power and communications settings. Some results name PT100/PT1000 platinum RTDs, DS18B20 digital probes or thermocouple assemblies: these are not ordinary NTC thermistors and need matching electronics and calibration. A module-only variant may not include its probes.
Selection checklist
- Identify the job: temperature sensing, inrush limiting, self-regulating heat or overtemperature protection.
- For sensing, match R25, B constant or resistance–temperature table, tolerance, measurement span and the controller's sensor setting. Consider self-heating and thermal contact.
- Choose mechanical format, mounting location, head, cable length and connector against the actual equipment drawing. Shape, resistance and appliance name alone cannot prove fit.
- For current-carrying and mains-connected parts, check the selected device's documented voltage, current, thermal and safety approvals plus the equipment service specification. Do not infer certification from a generic seller title.
- Verify exact variant and pack quantity; some shared listings vary B value, wire length, mounting style or module-versus-sensor contents.
FAQ
Can any 10K NTC replace a 10K B3950 probe? No. Match its resistance at 25°C, B curve, tolerance, packaging and controller calibration; B3435 and B3950 do not yield the same temperature reading across the range.
Are PT100 and PT1000 NTC thermistors? No. They are platinum resistance temperature detectors with different excitation and readout requirements. DS18B20 is a digital sensor, not a two-wire resistance equivalent.
Can a sensor thermistor replace a compressor starter or motor protector? No. A sensing element does not provide the current-handling, switching or protection function of a specified starter or protector. Use the appliance's service data and a qualified technician for mains equipment.
