An electrical model for a Peltier cell, based on the analogy between thermal and electrical variables, is proposed. The use of thermal models allows the global performance of thermocooling circuit and signal system to be checked by using electrical circuit analysis programs such as SPICE. The maximum error in the steady state between measured and simulated temperatures are less than 0.3/spl deg/C for hot temperature and less than 0.2/spl deg/C for cold temperature with 31.7/spl deg/C of temperature change.

This paper investigates low cost matching network for high impedance ultrasonic transducers. Matching the output transmitter impedance to high impedance transducer is important to maximize the transfer of power and improve the transmitting efficiency of the transducer, and so achieve better signal-to-noise ratio.In NDT ultrasonic applications based on piezoelectric transducers it is usual to introduce a tuned inductor, normally fitted in an experimental way, in order to cancel out the reactive component of the impedance of the transducer. More elaborated tuning solutions are well known, but in systems employing several transducers, such as arrays, is not feasible to connect all the transducer elements via a transformer or a complex network to their transmitters. Therefore, when the number of components is critical, if the system works in a narrow frequency range, this paper proposes to employ a simple L-C matching network with only one inductor and one capacitor. This topology is evaluated, by means of equivalent circuit analysis, computer simulation, and experimental assessment