Use of thermistors in radio tags
Brian H. Cresswell · ScholarWorks@UMassAmherst (University of Massachusetts Amherst) · 1992
Thermistors are semiconductor devices whose resistance changes with temperature. They are used in radio tags to vary signal pulse rate with temperature and, with appropriate circuit and tag design, provide a means to telemeter animal activity. In the circuit describes here (Fig. 1) a combination of capacitors and resistive components determines transmitter pulse rate and length. Pulses become shorter as pulse rate is increased, so overall current drain (and thus tag life) remains about the same, regardless of temperature. The thermistor circuitry adds only about 0.3 g to the weight of a tag.