The invention relates to a method and a device for improving heat transfer in a circular plate heat exchanger, as well as a heat transfer plate to be used therein. An aspect of the invention includes implementing non-standard IO adapters in a standardized IO architecture. The separate filament transformer subcircuit obviates the need for a conventional starter circuit for the fluorescent lamp. The precomputed calibration variables may be derived from respective three dimensional plots representing, respectively, detector outputs in relation to a calibrating input light with known values of the first and second actual bandwidth parameters. Other embodiments are described and claimed. Further, this semi-rigid rod may be encapsulated in a lightweight foamy tube to give it bulkiness.