Coupling capacitors vs isolation transformers?

[DKJones96]

I can't find anywhere a pros and cons of each on the net anywhere. Any links?

Also, in a capacitor coupled, say output stage, does the output transistor pull up to its biased say 18v and hang there with no output load unless there is AC or does the capacitor provide some sort of load under DC also?

Thanks in advance.

 

[ericj]

They perform different tasks.

Coupling capacitors block DC voltage from going across the connection - usually blocking DC from an output but occasionally an input has a DC bias too.

Transformers decouple the signal as well if used properly but unless specifically gapped for DC voltage, they need a coupling capacitor as well if they might be exposed to DC.

One of the more common uses for isolation transformers here is to decouple ground potentials, to prevent ground loops.