Intervalometer

Claim 2

Apparatus for launching a plurality of electrically fired rockets in a predetermined sequence, said apparatus comprising: a plurality of triggerable semiconductor current switching devices connected for selectively firing respective ones of said rockets, each device having a control terminal which is responsive to an input voltage above a predetermined threshold applied thereto for triggering the respective device to fire the respective rocket; a capacitor; means for charging said capacitor thereby to generate a progressively rising control voltage; and a resistive voltage divider for applying a different proportion of said control voltage to each of said control terminals; means for sensing the current drawn by said semiconductor switching devices in firing respective rockets and for generating a signal when each rocket is fired; and means responsive to said signal for discharging said capacitor and for providing a predetermined delay after said current ceases before permitting said capacitor to resume charging whereby the different rockets are launched in a sequence corresponding to the sequence of the different portions.

Claim 3

Apparatus as set forth in claim 1 wherein said means for discharging said capacitor includes a transistor amplifying means which is biased into conduction in response to current drawn by said switching devices.

Claim 4

Apparatus for launching a plurality of electrically fired rockets in a predetermined sequence, said apparatus comprising: a plurality of triggerable semiconductor current switching devices connected for selectively firing respective ones of said rockets, each device having a control terminal which is responsive to an input voltage above a predetermined threshold applied thereto for triggering the respective device to fire the respective rocket; a capacitor; means for charging said capacitor thereby to generate a progresSively rising control voltage; and a resistive voltage divider for applying a different proportion of said control voltage to each of said control terminals; and means including transistor amplifying means biased into conduction in response to the current drawn by any one of said switching devices in firing the respective rocket for discharging said capacitor and including also a second capacitor which maintains conduction through said transistor amplifying means to provide a predetermined delay after said current ceases before permitting said capacitor to resume charging whereby the different rockets are launched in a sequence corresponding to the sequence of the different portions.

Claim 5

Apparatus for launching a plurality of electrically fired rockets in a predetermined sequence, said apparatus comprising: a plurality of triggerable semiconductor current switching devices connected for selectively firing respective ones of said rockets, each device having a control terminal which is responsive to an input voltage above a predetermined threshold applied thereto for triggering the respective device to fire the respective rocket; a capacitor; means for charging said capacitor thereby to generate a progresSively rising control voltage; and a resistive voltage divider for applying a different proportion of said control voltage to each of said control terminals; and means including transistor amplifying means biased into conduction in response to the current drawn by any one of said switching devices in firing the respective rocket for discharging said capacitor and including also a second capacitor which maintains conduction through said transistor amplifying means to provide a predetermined delay after said current ceases before permitting said capacitor to resume charging whereby the different rockets are launched in a sequence corresponding to the sequence of the different portions.