For a signal device comprising a plurality of percussively ignitable flashlamps mounted on a support member and arranged in an array with respectively associated preenergized striker springs, a selective actuating mechanism for sequentially releasing the striker springs to fire respective flashlamps in response to successive hand actuated indexing. The selective actuating mechanism comprises a spring-loaded ratchet bar retained in a longitudinal channel in the support member in combination with a slidable member which is also retained in the channel in engageable contact with the ratchet bar. The lamps and striker springs are mounted in a row parallel to the channel with the strikers projecting beyond the periphery of the channel. The slidable member, which may comprise a folded flat spring having a first tang for engaging the ratchet bar and a second tang for engaging a surface of the channel, has a trip wire projection which is aligned with the projecting portions of the strikers. Upon successive hand actuation of the ratchet bar, the slidable member is indexed along the channel so that the trip wire projecting therefrom sequentially releases the preenergized strikers to fire respective flashlamps.