The DynaSense® MK I is a digital, indicating, on/off temperature controller, which allows instant system setup and provides pinpoint accuracy with on/off control action of heating and cooling devices operating alternately and independently. The resistance vs. temperature change of the platinum RTD probe is amplified by a complex solid state assembly, which controls a rugged electro-mechanical, two position relay in direct relation to system demand and deviation from temperature setpoint. Indicating accuracy is ±1 digit. The unit provides a bi-stable output relay, which alternates the heat or cool device input to the temperature controlled system in response to the RTD sensor temperature and produces a classic sawtooth (on/off) type response curve at the set-point temperature. An adjustable dead-band control provides cycle rate and on/off differential adjustment.