Abstract: A controller for a system of the type including a variable temperature heat source arranged in heat exchange relation with a fluid circulating circuit, and a variable speed pump disposed in said circuit for varying the flow rate of fluid therethrough in response to variations in the temperature of the fluid. The controller includes a probe for sensing a temperature indicative of the temperature of the fluid in the circuit and for generating a first signal indicative thereof; means for generating a reference signal indicative of a predetermined temperature; means for comparing the first two signals and generating a third signal indicative of the difference therebetween; means responsive to the third signal for generating an analog control signal; means responsive to the analog control signal for varying the pump speed as a function of the control signal for equalizing the first and second signals.

Abstract: A balancing radiometer for measuring the intensity of incident electromagnetic radiation comprises: a pair of identical sensors, each including a thermally conductive substrate, at least one surface of the substrate being comprised of an electrically insulating material, and means disposed on the one surface for resisting the flow of electric current and absorbing incident radiation; means for shielding one of the two sensors from the radiation source, the other sensor being unshielded; means disposed in thermal conducting relation with the substrate of the shielded sensor for providing a first signal proportional to the temperature of the shielded sensor; second means disposed in thermal conducting relation with the substrate of the unshielded sensor for providing a second signal proportional to the temperature of the unshielded sensor; means for comparing the first and second signals; variable power supply means responsive to the signal comparing means; means for connecting the power supply means to the shi