Journal of Electrical, Control and Technological Research 1 (2020) 17 – 22 Journal of Electrical, Control and Technological Research Journal homepage: www.sciengtexopen.org/index.php/jectr Response characteristics of a negative temperature coefficient thermistor S. F. Iyere a, , B. O. A. Ozigi b , J. K. Yeboah c 1. Introduction A system is said to be time variant if the time response (time advance or time delay) of the input signal leads to a time shift in the output in response with the input signal. In other words, the characteristics of a time variant system changes with time [1]. A thermistor is a thermally sensitive resistor whose resistance depends on its temperature at a given time. It is one of the most popular temperature sensors, commonly used for measuring temperature. Some materials exhibit appreciable changes in resistance when their body temperature changes, in accordance to the nature of materials they are made of. Thermistors utilized in photocopiers are used for temperature monitoring and control. Their basic function is temperature control of the heater/fusing unit of the copier to prevent over heating of the heater/fuser lamp located right inside of the heat roller. The heat roller performs the function of dry heating of the toner image transferred to the photocopying paper during the process of copying. This prevents the dry ink (toner) used for printing to be deleted or cleaned ———  Contact e-mail: Sunday4success2007@gmail.com a, c Department of Electrical & Electronic Engineering, Ambrose Alli University, Ekpoma, Nigeria; b Power Equipment & Electrical Machinery Development Institute, Okene, Nigeria 2756–6765 / © 2020 the authors. Published by Sciengtex. This is an open access article under CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) ARTICLE INFO ABSTRACT Article history: Received 28 December 2019 Revised 1 February 2020 Accepted 20 February 2020 Published 1 April 2020 This article focuses on the thermistor as a device that is widely used for temperature measurement and control in most electrical and electronic devices and appliances. The research is based on the type of thermistor used in photocopiers with particular reference to Minolta Bizhub (model- 210) photocopier. The resistance and temperature were recorded by the application of conventional heat to deduce the response curves of resistance versus temperature and resistance/time. Results obtained from the characteristics show that the thermistor employed in the photocopier is a negative temperature coefficient (NTC) device. Also, there was a time variation in the response of the thermistor resistance to temperature changes, which indicates that the thermistor under test functions as a temperature control device. The shape of resistance versus temperature curve appeared to be similar to that of a typical NTC thermistor characteristic. https://doi.org/10.37121/jectr.vol1.113 Keywords: Resistance Response curves Temperature coefficient Temperature measurement Thermistor