In practice, voltages of the order of 1 V are are produced by electromagnetic radiation in the background. Hence signals of this size are not of practical use. Thermoelectric and piezoelectric voltages are of the order of 1mV and measurement systems must be designed to sense such voltages. A preamplifier is a dedicated piece of hardware that improves the ratio of the transducer output. This is further amplified to the level of around 1V to run a display device or for AD conversion. In light of this discussion Figure 1.2 can be expanded to Figure 1.6.