1371887 Flash apparatus POLAROID CORP 18 April 1973 [24 April 1972 5 Feb 1973] 18745/73 Heading G2X An adapter for a camera having a flash circuit calibrated for firing flash lamps of a given impedance includes switching means responsive to a lamp firing signal to provide an actuating signal for an electronic flash unit, the adapter presenting during such operation an impedance equivalent to that of a flash lamp. Fig. 2 (not shown) sets out the details of a flash lamp firing circuit for firing in sequence a series of three flash lamps (60a, 60b, 60c,). When a lamp fires successfully, a predetermined impedance is sensed by a monitoring unit, which presents a signal activating a fixed delay and inhibiting a lightsensitive circuit which controls the exposure under ambient light conditions. Fig. 4 shows an adaptor arrangement for actuating an electronic flash 178, and which connects with the flash lamp firing circuit 40 at terminals 182, 184. The corresponding leads 186, 188 are inter-connected by a reed-type relay 190 which represents an inductive load. A fixed resistor 196 is also coupled across leads 186, 188 in parallel with relay 190, this resistor having an impedance characteristic closely similar to those of the flash lamps. Thus as the firing circuit is energized, relay 190 is energized to close a switch 192 which closes the circuit to the electronic flash 178. This is. detected by the monitoring unit as a successful flash ingition, which presents a signal as before.
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