chromatic stroboscope fork unit
Date1941
Inventory NumberWJ0434
ClassificationFrequency Meter
Subject
Maker
C.G. Conn, Ltd.
founded 1875
User
Psycho-Acoustic Laboratory, Harvard University
1940 - 1962
Cultural Region
Place of Origin
Place of Use
Dimensions20.3 x 35.6 x 48.3 cm (8 x 14 x 19 in.)
Material
AccessoriesBlack rectangular case
DescriptionRectangular metal case with slanted front panel with large dial and arched window with mirror strip and arched scale. Open grating on back half.
In black rectangular case with textured material and removable lid.
This object is one component of the stroboscope called the "fork unit" or "tuning unit".
In black rectangular case with textured material and removable lid.
This object is one component of the stroboscope called the "fork unit" or "tuning unit".
Signedin silver on front plate: CONN / CHROMATIC / STROBOSCOPE / FORK UNIT / C.G. CONN, LTD. / ELKHART, IND.
Inscribedstamped in white inside lid and on front panel: OEM-sr PAL / 10395
in red on top: 76-B-808 / Tr-HU-2/7/61
Curatorial RemarksThis object is the so-called "fork unit" or "tuning unit", which sets the speed of the rotating disks. The stroboscopic disks themselves would be on a unit place above it called the "scanning unit" (see manual in Primary Sources).
FunctionA chromatic stroboscope is a very precise frequency measuring device, originally developed by the C.G. Conn musical instrument company to measure the frequency of musical instruments. They were sold under the name "Stroboconn".
The instrument has disks with several alternating white and black strip patterns rotating at a set speed (slighltly different), which corresponds to an acoustic frequency. The disks are illuminated from the back with a light source that is connected to a microphone receiving an audio signal from the musical instrument. If the frequency of the instrument (and the backlight) matches the frequency of the rotating disk, the pattern appears static.
Chromatic stroboscopes later found useful applications in many other fields of study where frequency measurements were needed.
For details of its use, see the manual listed in Primary Sources.
The instrument has disks with several alternating white and black strip patterns rotating at a set speed (slighltly different), which corresponds to an acoustic frequency. The disks are illuminated from the back with a light source that is connected to a microphone receiving an audio signal from the musical instrument. If the frequency of the instrument (and the backlight) matches the frequency of the rotating disk, the pattern appears static.
Chromatic stroboscopes later found useful applications in many other fields of study where frequency measurements were needed.
For details of its use, see the manual listed in Primary Sources.
ProvenancePsycho-Acoustic Laboratory, Harvard University.
General Radio Company
Date: ca. 1924-1926
Accessories: crystal unit; removable coil; 3 (?) batteries (removed during FAE inventory).
Object number: RS0655
George Washington Pierce
Date: ca. 1924-1926
Object number: RS1441
General Radio Company
Date: 1915-1918
Accessories: loose calendar page with circuit diagram
Object number: 2012-1-0034
Radio Corporation of America
Date: 1923
Object number: RS0039
