Posts tagged ‘PTC’

Thermistor Parameter Measurement — II

Last time I showed a simple circuit that can be used to measure unknown thermistor parameters. The circuit is basically just a power MOSFET using a voltage and duty cycle controlled PWM signal to drive the gate and thus generates a temperature reference which is measured by both the unknown thermistor and the precision temperature sensor LM335. By measuring the voltage drop across the thermistor at different temperatures, we can obtain the R-T curve of the thermistor and thus estimate the parameters that define the R-T curve using some known models. Continue reading ‘Thermistor Parameter Measurement — II’ »

Thermistor Parameter Measurement — I

Over the years, I have gathered quite a few NTC and PTC thermistors. But most of them are unmarked so it would be difficult to use them in an accurate way without knowing the parameters. So I decided to build a simple circuit that can be used to trace the temperature-resistance curve, and the parameters can then be estimated using the measured data points. Continue reading ‘Thermistor Parameter Measurement — I’ »