Abstract: A drive for a slide projector utilizing circular magazines which permits the slide projector to be used with circular magazines having differing numbers of slide compartments. A variable gear unit, including a shift mechanism to vary the gear ratio, couples a drive motor to a drive ring for rotation of a circular magazine disposed in the projector. The circular magazine is rotated in a stepwise manner, the length of each step depending upon the number of slide compartments which the particular magazine contains. The drive ring is made sufficiently large to accommodate most conventional circular magazines and includes a cam which extends radially inwardly and which is adapted to engage a notch formed on the outer surface of a circular magazine. The circumferential step length is adjusted by changing the gear ratio in the variable gear unit by longitudinal movement of an intermediate drive shaft.

Abstract: Apparatus is disclosed for viewing photographic slides carried in a long magazine by a slide projector which is configured to accept only a circular slide magazine or carrousel. This invention provides a simple and efficient mechanism for using long magazines with a circular magazine projector without the need of first transferring by hand all of the slides from the long magazine into a circular magazine. An attachment adapted to be fastened to the projector housing has a covered channel for accepting and advancing a long magazine inserted therein. Adjacent the long magazine within the attachment is an intermediate storage tray which contains slide compartments and which is moved synchronously with the long magazine. Slanting guide rails extend from the long magazine to the intermediate storage tray, and these rails individually transfer the slides from the long magazine into the storage tray as the long magazine is advanced.