An Automatic Direct Inking Audiofrequency Response Recorder
Benjamin Olney · The Journal of the Acoustical Society of America · 1942
This recorder and oscillator assembly draws curves in ink on standard semi-logarithmic graph paper. The frequency range is from 30 to 10,000 cycles per second and the ordinate scale covers 40 db in 1-db steps. Internal calibrating means are provided for establishing reference levels of pressure and voltage. The graph sheet is carried on a flat platen and is entirely visible at any stage of the recording. The recording pen is driven by a vibrating type of motor which has particular advantages for this application. Convenient adjustments are provided to permit recording the average value of a fluctuating quantity such as the output of a rotating microphone.