-- card: 47944 from stack: in -- bmap block id: 0 -- flags: 0000 -- background id: 3551 -- name: -- part contents for background part 16 ----- text ----- 171 -- part contents for background part 3 ----- text ----- envelope follower -- part contents for background part 4 ----- text ----- An AC-to-DC converter coupled with a lag processor to produce a DC envelope proportional to the AC input envelope.