The first question should be on the order of, "Why have you chosen this particular device?" Asking why would shed light on possibilties such as, "The device is part of a panel meter that we're using in our class..." or something similar. Another adequate response might well be, "Because I have one on hand." If one is wanting to use something already on hand, it's no sin. Better that than simply throwing it out.

The man asked for help in doing THAT and not in building a high-quality data conversion subsystem.

There are many ways, it's been said, to "skin a cat" but it's his cat, so, if there's help available, let's help him do that, which is what he wants, and what he asked, and not something else. If he's later persuaded to try something else, well, that' OK, and possibly better, but first, he should have a shot at what he wants to do. Clearly, this couldn't be for production, as the majority of ADC's are much less costly than the one about which he asked.

RE