National Instruments BNC-2090 User Manual

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National Instruments BNC-2090 User Manual Manual pdf 28 page image

Chapter 3 Signal Conditioning Application ExamplesNational Instruments Corporation3-3BNC-2090 User ManualSoldering and Desoldering on the BNC-2090Some applications require you to modify the PWB, usually by removing0 Ω jumpers and adding components. The BNC-2090 is shipped with0 Ω jumpers in the C and D positions (see Table 3-1 and Figure 3-2).Use vacuum-type tools when desoldering on the BNC-2090 and avoiddamaging component pads.Use a low-wattage soldering iron (20 to 30 W) when soldering to theboard. You should use only rosin-core, electronic-grade solder. Acid-core solder damages the printed circuit board and components.Analog InputEach analog input signal has several open positions for passive signalconditioning components. Four of these positions are designated asresistors and one is designated as a capacitor. The factory-defaultpositions for the 0 Ω jumpers are the C and D positions of the inputnetwork, as shown in Figure 3-2. You can remove these 0 Ω jumpers tobuild analog input signal conditioning circuits. You can also addpassive analog input signal conditioning, such as filters and dividers.The component positions are different for each channel. Figure 3-2shows the onboard equivalent circuit.Table 3-1. Channel Component PositionsChannel Position in Figure 3-2Differential Single-Ended A B C D E0 0, 8 R1 R2 R19 R20 C11 1, 9 R3 R4 R21 R22 C22 2, 10 R5 R6 R23 R24 C33 3, 11 R7 R8 R25 R26 C44 4, 12 R9 R10 R27 R28 C55 5, 13 R11 R12 R29 R30 C6