Let's say a human engineer comes across an alien electronics lab.
It occurs to me that electrons are electrons, if the aliens are at a similar state of development to us then at least the simplest (discrete?) components might be similar in operating principle and should be recognisable. On the other hand, alien electronics could be very different.
the aliens are at a similar level of technology to what we have today.
the engineer has stumbled upon the equivalent of a university electronics lab, well equipped makerspace or very well equipped hobbyist's workshop.
the aliens have similar requirements for their components that we do, mainly being cheap to produce and reasonably reliable. They identify components by sight, like most humans.
the only tool the engineer has with earth-style units is his trusty multimeter.
How different are alien electronics likely to be? What sort of components would the engineer be able to recognise first and how? How quickly could he begin working with alien tools and components?
Having read the answers and comments so far, I would like to clarify some points. I'm sorry if I did not make myself clear before.
The aliens are not significantly more advanced than us. Their electronics are based on the same principles as most Earth electronics, generally not bio-electricity, weights and pulleys, etc. Memristors (which, admittedly, I only just learned about) are fair game.
Silicon is a fairly common element. It would be strange if the aliens did not have access to it. Ditto for anything else required by Earth style electronics.
The alien lab certainly has more tools than a mere multimeter, except they are all marked in a different language. Addition: The engineer has access to a power-supply with a knob for selecting voltage and limiting current. He doesn't know what the units are however. (I foresee calibration involving a melted piece of wire...) Likewise, oscilloscopes, logic analysers, etc., are available, but are all marked in alien units. (Anything a well equipped electronics lab would have, the aliens also have.)
(I don't think I have broken (m)any answers here, if I have, sorry.)