Power Amplifier Inside A electric guitar pickup is basically just like a dynamic mike coil. For decades, energetic microphones have been sent with the style coil mounted on the primary of the microphone's transformer, and maybe not referenced to surface (‘floating'). The microphone's situation is typically linked to the cable shield, that is connected to the microphone amplifier's ground (see Rane's website for more discussion).
By and big, active microphones are extremely calm units as a result of the mix of transformer solitude and healthy, hanging transmission lines all through, in addition to guarded, humbucking coils.
So why not instruments? Guitars are once affected by noise. Humbucking pickups are only an incomplete (though crucial!) solution. The most obvious option is always to move the guitar pickup to a healthy production, as being a microphone. A similar thought was published this 2001 patent application such as Power Amplifier Inside?