Low Noise Transformer

Figure 11-5 reveals two low-noise construction techniques, as applied to a typical flyback transformer. We should compare the right-hand electrical schematic with its equivalent winding version to the left. In the discussion below, we note that though transformers with split windings are not being explicitly discussed here, the same principles can be easily extended and applied to them, too. Here are some observations ... 

Wavenumber precision and low noise levels allow spectra with slight differences to be subtracted from each other to expose those differences. Fourier transform instruments are not as accurate as dispersive spectrometers for measuring transmittance. 

All broadband spectra were amplified by a low-noise preamplifier with a dynamic range > 1,000, and a broadband main amplifier. The amplified time-domain signal is digitized by a 20 MHz, 9 bit Bruker ADC with 128 K words of buffer memory, and Fourier transformed by a Bruker array processor (128 K word FFT in 8 sec). 

Figure 11-5 Two Alternative Low-noise Winding Arrangements for a Flyback Transformer...

Optical frequency of the HeNe (15802.78 cm ) and the mirror velocity v is measured in cms . A typical mirror velocity for a FT-NIR spectrophotometer is v = 0.633 cms . The HeNe laser frequency is then modulated at 20 kHz, which puts the lower frequencies in the audio range where low-noise electronics are available to digitize and transform the signal. The detector response is measured at every zero-crossing of the HeNe laser signal. 

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