A Photoelectric Film Tachometer

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Publisher: SMPTE
Doc Type: Journal Article
Article Type: research-article
Abstract: It is often required to know the linear speed of motion-picture film. When a sprocket-drive machine is utilized, it is a relatively simple operation to install a tachometer generator and indicator. However, in the case of friction-drive machines, a simple monitoring of the machine motor gives only an approximate speed, due to film slippage and machine overdrive. One method to indicate speed on a friction-drive machine is to use a metering spool in conjunction with a pinch roller and a tach generator; however, this approach is not too safe or reliable. In an attempt to overcome these problems, a “skip-tooth” sprocket has been designed which is free wheeling and does not place any drag on the film. To this sprocket a slotted disc is attached which acts as a chopper for a reflected light beam. The chopped beam is then converted to an electric current which is displayed on a meter calibrated to read directly in feet per minute of film travel.
Publication Date: 1970-02-01
DOI: 10.5594/J10742
Link: https://doi.org/10.5594/J10742
Author(s): David J. Degenkolb, Jack P. Hall

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David J. Degenkolb and Jack P. Hall; A Photoelectric Film Tachometer, Journal of the SMPTE ( Volume: 79, Issue: 2, February 1970); SMPTE, 1970. Available at https://doi.org/10.5594/J10742

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David J. Degenkolb and Jack P. Hall; A Photoelectric Film Tachometer, Journal of the SMPTE ( Volume: 79, Issue: 2, February 1970); SMPTE, 1970. Available at https://doi.org/10.5594/J10742

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David J. Degenkolb and Jack P. Hall; A Photoelectric Film Tachometer, Journal of the SMPTE ( Volume: 79, Issue: 2, February 1970); SMPTE, 1970. Available at https://doi.org/10.5594/J10742

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<span class="citation">David J. Degenkolb and Jack P. Hall; <cite>A Photoelectric Film Tachometer</cite>, Journal of the SMPTE ( Volume: 79, Issue: 2, February 1970); SMPTE, 1970. Available at <a href="https://doi.org/10.5594/J10742" target="_blank" rel="noopener">https://doi.org/10.5594/J10742</a></span>

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David J. Degenkolb and Jack P. Hall; A Photoelectric Film Tachometer, Journal of the SMPTE ( Volume: 79, Issue: 2, February 1970); SMPTE, 1970
doi: 10.5594/J10742
url: https://doi.org/10.5594/J10742

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David J. Degenkolb and Jack P. Hall; <cite id="bib-10-5594-j10742">A Photoelectric Film Tachometer</cite>, Journal of the SMPTE ( Volume: 79, Issue: 2, February 1970); SMPTE, 1970
<span class="doi">10.5594/J10742</span>
</li>