Abstract: Actuating circuitry which may be used with a contact exploder, useful on a orpedo, for example, which is sensitive not only to direct hits but also to abrasive damage or sea water exposure caused by grazing contact, but insensitive to changes in its velocity or momentum or unwanted environmental background, such as shock, vibration and electromagnetic field variation. The exploder includes a normally insulated and shielded wire which traverses that part of the surface of the missile which is most likely to make contact with a target. The wire is so connected into associated actuating circuitry that it will cause explosion if: (1) even grazing contact with a target causes removal of even a small amount of the insulation and shielding of the wire, which causes grounding of the circuitry at the wire; or (2) even grazing contact opens or breaks the wire at any point.