Abstract: A current limited strobe charging circuit in which the charging current is automatically limited during the time required to reform the primary storage capacitor after a long period of non-use without materially effecting the current flow and time required to subsequently recharge the storage capacitor after it has been reformed includes a positive temperature coefficient resistor serially connected therewith to switch from a low resistance mode of operation to a high resistance mode of operation as a result of its own internally generated I.sup.2 R heat.

Abstract: A cinematographic system including a programmable viewing apparatus by which an exposed photographic film strip in a multipurpose cassette may be processed, viewed by projection, and rewound, either entirely or for a selected film length for replay, without removal from the viewing apparatus. A control circuit is provided which continuously measures the position of the film strip in the cassette and precludes projection of the leading end of the film strip in response to signals received from the electronic logic system of the viewing apparatus. The signals condition the circuit to count in either the forward or reverse direction depending upon the direction of film strip movement. The count, which corresponds to the position of the film strip, is continuously displayed by the viewing apparatus. When the count is at or below a predetermined number corresponding to the length of the leading portion, the circuit will prevent the projection lamp from turning on during a project cycle.

Abstract: An electrical regulator for operating a photographic illuminating lamp provides two controls on the triggering of a phase-controlled power switch. One control employs a differential switch in a feed-forward loop that adjusts the potential at which a timing capacitor triggers the power switch. The other control is a feedback loop which controls the rate at which the timing capacitor is charged. The regulator combines the feed-forward and feedback controls to regulate the mean square of the lamp voltage for a wide range of input voltage amplitudes and frequency.

Abstract: A programmable viewing system for processing and viewing cassette contained photographic film strips including a chassis defined by a centrally disposed vertical plate-like casting on which all internal viewer components cooperable mechanically and/or optically with the cassette are mounted together with a cassette well by which the cassette may be registered with such viewer components. A programming cam disc is rotatably carried by the casting for controlling both electrical switches for controlling an electronics logic system as well as shiftable viewer component positioning members, one on each side of the casting. The programming cam disc further controls cassette ejection. The program cam disc, together with contacts in the cassette, also control the film processing cycle during which the film is transported between spools and processing fluid is applied to the film strip.

Abstract: A programmable viewing system for processing and viewing cassette contained photographic film strips including a chassis defined by a centrally disposed vertical plate-like casting on which all internal viewer components cooperable mechanically and/or optically with the cassette are mounted together with a cassette well by which the cassette may be registered with such viewer components. A programming cam disc is rotatably carried by the casting for controlling both electrical switches for controlling an electronics logic system as well as shiftable viewer component positioning members, one on each side of the casting. The programming cam disc further controls cassette ejection. The spools of the cassette are driven by an electric motor through a clutch.