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Instead of using a slightly larger number of inexpensive multiple-sourced parts, you could consider using a part designed for this kind of application, the TI ISO1211. See Figure 3. I think values of Rsense = 560 ohms, Rthr = Rshunt = 1K and C = 100uF/50V would work, but check that yourself. It will run off the 3.3V Pi power supply. You might want to use a ...


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Yes, there are quad optoisolators (one 16-pin package, either surface-mount (0.1" or 0.05" pitch) or old-fashioned DIP). Just go to your favorite parametric search engine, such as Digikey's and select 4 channel optoisolator. Product Index>Isolators>Optoisolators - Transistor, Photovoltaic Output Around 150 choices with different packages, ...


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From the optocoupler's point of view, common-mode transients happen when the voltages at the inputs change relative to the voltages at the outputs, but when the voltage between the A and K inputs stays the same. In this circuit, this implies that the voltage between VDDiso and GNDiso does not change. In other words: the LED driving circuit is not affected by ...


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Here is a potential idea which uses a digital isolator (Silicon Labs Si8610 Data Sheet) on the output. The input has lightning strike protection diodes and a differential amplifier with high common mode rejection ratio; both required for a 25m cable exposed to hazards. You could also add filter capacitors. All parts are relatively inexpensive. The ...


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