Abstract: A method and apparatus for detecting leaks within a vacuum system by narrow band detecting and amplifying a particular ultrasonic frequency peculiar to such leaks is disclosed. The device is formed as a hand held probe having a transducer and amplifier both peaked to the particular frequency sought along with a visible display and audible alarm for indicating the level or intensity of the particular frequency sought and audibly notifying the user when that sound level reaches some prescribed intensity. Appropriate shielding and filtering to prevent spurious actuation of the device are also disclosed.

Abstract: Copy production machine having a print mode for making copies under automatic control interruptible by a copy mode of making copies. In the print mode images to be copied are automatically supplied to a copy production portion. In the copy mode, a variety of image supplying techniques may be employed. Copy output means separate copies made from the two modes. In the print mode images are preferably precollated whereas in the copy, mode produced copies are collated. In a print mode plural image sources may be employed, such sources being activated ad seriatim.