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I'm a novice to electronics, and I was wondering if someone would clarify an experiment I just witnessed. A photodiode was set up to receive some signal. This signal is then read by a transimpedance amplifier. Finally, the signal is then “sampled” by a Digilent Analog Discovery. What is the purpose of using this Digilent Analog Discovery (that is, what is meant by it being used for "sampling", in this context)? This device seems to be a kind of portable, compact, all-in-one electronics bench-top device; and, in this case, it seems to me (I could be wrong) that it is doing the job of an oscilloscope. Furthermore, this device seems to be quite expensive, so why would someone use it instead of just making a cheap circuit themselves? Is it difficult/impractical/expensive to build a substitute circuit to do this job yourself, or is it probably just out of convenience for the experiment? In a production device, would engineers still include the Digilent Analog Discovery (I seem to doubt this), or would they just making their own custom board/part (since it seems that it would be much cheaper, and technically optimised to whatever their device is). I would greatly appreciate it if people would please explain what's going on here.

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what is meant by it being used for "sampling", ... in this case, it seems to me (I could be wrong) that it is doing the job of an oscilloscope

Sampling = making voltage readings. In this case the job probably could be performed by an oscilloscope.

The Analog Discovery is not just an voltage sampling device. It also has a 2 channel arbitrary waveform generator as well as digital I/O lines. And all of these are fully programmable so you can coordinate their use with each other to create custom measuring instruments. And don't forget the programmable voltage supplies.

A classic example is the impedance analyzer. You apply a specific frequency sine wave input into a device and measure the output amplitude and phase shift. Then you repeat this for several different frequencies. This requires coordination between a function generator and your voltage sampling device. And then you need to process the data and display the results in a Bode plot.

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  • \$\begingroup\$ Thanks for the clarification. What about the production question? For a production device, wouldn’t engineers just design/build this part themselves and save a lot of money (and have a more optimised device)? So I’m guessing it was just used as a matter of convenience for the experiment, right? \$\endgroup\$ Jul 20, 2021 at 3:09
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    \$\begingroup\$ I'm not sure where your question is coming from. Of course for a commercial product you want to reduce hardware costs as much as possible. I don't think anyone would include an AD in a commercial product, but I've seen boards that are meant to be used with an AD. \$\endgroup\$
    – ErikR
    Jul 20, 2021 at 3:31

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