Abstract: Precisely positionable apparatus for collecting corona-generated current. A conductive sheet or coating is affixed to one side of an insulative sheet material. A low residue of nonresidue adhesive alone or carried by a tape is affixed to the other side of the insulative sheet. The sheet is then placed on a copier photoconductor or photoconductor carrier such as a drum, adhesive side to the carrier. The adhesive keeps the sheet flat against the surface at which the measurement is to be made. A shock protection line including front-to-back parallel diodes is connected between the conductive surface and ground. With the corona on, and the carrier in position, a current measuring device is connected between the conductive surface on a tab of the sheet and ground.