A method for operating a thermocycler instrument, comprising the steps of a. supplying power to a thermocycler instrument that includes at least two generally opposing and spaced apart thermoelectric devices, a sample holder therebetween with one or more bores for receiving one or more sample tubes, and heat exchangers associated with the thermoelectric devices and projecting generally away from the sample holder; b. applying a voltage signal capable of having a positive polarity and a negative polarity to the at least two generally opposing and spaced apart thermoelectric devices of the thermocycler via at least one circuit; c. applying a voltage signal to an air mover circuit for rotating an impeller of an air mover for convectively expelling air from the thermocycler; d. controlling the polarity of the voltage signal that is applied to the thermoelectric devices to repeatedly alternate the operation of the thermoelectric device between a first condition of supplying heat to the sample holder and a second condition removing heat from the sample holder; e. obtaining a first sample holder electrical signal from a first temperature sensor corresponding with a temperature within the sample holder that approximates the temperature of a sample; f. obtaining a second electrical signal from a second temperature sensor corresponding with a temperature from a heat exchanger; and g. employing the first sample holder electrical signal and the second electrical signal for determining values for controlling power delivery to be delivered to the thermoelectric devices; wherein the one or more bores for accepting the one or more sample tubes within the thermocycler experience thermal uniformity within ±1°C of one another. a. supplying power to a thermocycler instrument that includes at least two generally opposing and spaced apart thermoelectric devices, a sample holder therebetween with one or more bores for receiving one or more sample tubes, and heat exchangers associated with the thermoelectric devices and projecting generally away from the sample holder; b. applying a voltage signal capable of having a positive polarity and a negative polarity to the at least two generally opposing and spaced apart thermoelectric devices of the thermocycler via at least one circuit; c. applying a voltage signal to an air mover circuit for rotating an impeller of an air mover for convectively expelling air from the thermocycler; d. controlling the polarity of the voltage signal that is applied to the thermoelectric devices to repeatedly alternate the operation of the thermoelectric device between a first condition of supplying heat to the sample holder and a second condition removing heat from the sample holder; e. obtaining a first sample holder electrical signal from a first temperature sensor corresponding with a temperature within the sample holder that approximates the temperature of a sample; f. obtaining a second electrical signal from a second temperature sensor corresponding with a temperature from a heat exchanger; and g. employing the first sample holder electrical signal and the second electrical signal for determining values for controlling power delivery to be delivered to the thermoelectric devices;