Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,544   Posts: 1,544,427   Online: 1072
      
Page 2 of 2 FirstFirst 12
Results 11 to 18 of 18
  1. #11
    BetterSense's Avatar
    Join Date
    Aug 2008
    Location
    North Carolina
    Shooter
    35mm
    Posts
    2,864
    . Another way of doing timing stuff would be a microcontroller of some sort, but those generally also have set clock frequencies that are pretty much entirely independent of current and voltage
    All microcontrollers I know of have either crystals or RC resonators to get them going. In both cases the supply voltage doesn't matter, it just has to be enough and not too much.

    Does anyone know anything about Technics turntables? The one in my avatar has a strobe light that you can use to adjust the platter speed, but I don't know if it syncs off the mains or not, and I also don't know if the mains frequency changing would cause the turntable speed to change.
    f/22 and be there.

  2. #12
    MattKing's Avatar
    Join Date
    Apr 2005
    Location
    Delta, British Columbia, Canada
    Shooter
    Multi Format
    Posts
    12,389
    Images
    60
    Quote Originally Posted by BetterSense View Post
    All microcontrollers I know of have either crystals or RC resonators to get them going. In both cases the supply voltage doesn't matter, it just has to be enough and not too much.

    Does anyone know anything about Technics turntables? The one in my avatar has a strobe light that you can use to adjust the platter speed, but I don't know if it syncs off the mains or not, and I also don't know if the mains frequency changing would cause the turntable speed to change.
    I bet the Technics turntable has different speed synch marks for 50 Hz and 60 Hz power, so I would guess that it does synch off the mains.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  3. #13
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,219
    Many turntables just have a simple neon lamp for setting the speed of the platter. This blinks with the mains frequency. I notice on my Technics, the light is RED rather than neon orange, but either way, it blinks with the mains frequency.

  4. #14

    Join Date
    Mar 2011
    Location
    Lynden, Warshington
    Shooter
    Multi Format
    Posts
    74
    I'm not at all happy about this tolerance loosening- I have two old IBM/Simplex school clocks circa 1960 which (because of accurate frequency regulation) are indeed very accurate. Granted, NIST atomic clocks put these in the dust, but I like them :-)
    I would love to use the "FP" flash setting on my camera, but I cannot find "Flash Powder" anywhere... such is life.

  5. #15
    BetterSense's Avatar
    Join Date
    Aug 2008
    Location
    North Carolina
    Shooter
    35mm
    Posts
    2,864
    Many turntables just have a simple neon lamp for setting the speed of the platter. This blinks with the mains frequency.
    Well, see this is where I'm going. If the neon strobe blinks with the mains frequency, and the turntable's speed itself is proportional to the mains frequency, then if the mains frequency changes down say 10%, then the strobe will strobe 10% slower and then maybe the turnable itself will spin 10% slower so I will not actually be able to tell except the music might sound funny. I doubt I would actually be able to tell because I used to have a much cheaper Marantz turntable with a synchronous motor, and it was 4% slow, and you really couldn't tell.
    f/22 and be there.

  6. #16
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,219
    Quote Originally Posted by BetterSense View Post
    Well, see this is where I'm going. If the neon strobe blinks with the mains frequency, and the turntable's speed itself is proportional to the mains frequency, then if the mains frequency changes down say 10%, then the strobe will strobe 10% slower and then maybe the turnable itself will spin 10% slower so I will not actually be able to tell except the music might sound funny. I doubt I would actually be able to tell because I used to have a much cheaper Marantz turntable with a synchronous motor, and it was 4% slow, and you really couldn't tell.
    Yes that is correct, but the deviation in mains frequency is only going to go up to 0.004% in some parts of the country. Only the vinyl audiophiles with oxygen-free hookup wire neatly arranged at right angles will be disturbed by the news. (they won't be bothered by this if they don't know about it ).

    Most DVMs should have a frequency counter. I just checked my mains and I get a steady 122.7V and 60.00 Hz.

    There is already a similar thread to this one on "audiokarma.org" http://www.audiokarma.org/forums/sho...ains+frequency

  7. #17
    Nicholas Lindan's Avatar
    Join Date
    Sep 2006
    Location
    Cleveland, Ohio USA
    Shooter
    Multi Format
    Posts
    2,375
    Images
    4
    The strobe on turntables is usually a neon bulb syncing to the line frequency. However, the turntable itself, if it is modern, would run off a quartz crystal. When the table was designed the line frequency strobe was a check on the operation of the crystal and motor - now the table's crystal and platter motor are a check on the operation of the power grid...

    The article states a 20min/year error, but also a 14 seconds / day error. The daily error is about 0.02% - and quite irrelevant for any photographic purpose. An untrimmed bog-standard quartz microprocessor crystal can have an initial tolerance of 30ppm or 0.003% - about the same as the proposed sloppy power line timing.

    I would say, though, that the 14 minutes a year is a pain in the but when it comes to resetting clocks, but then power failures mean the clocks need resetting several times a year anyway. Old analog electric clocks will be a bother, but I only have one of those left.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  8. #18
    Steve Smith's Avatar
    Join Date
    May 2006
    Location
    Ryde, Isle of Wight
    Shooter
    Medium Format
    Posts
    8,596
    Images
    122
    Quote Originally Posted by Nicholas Lindan View Post
    The strobe on turntables is usually a neon bulb syncing to the line frequency. However, the turntable itself, if it is modern, would run off a quartz crystal.
    Yes, otherwise, if the motor was also synchronous to the mains frequency, it would always be correct to the strobe and you wouldn't be able to adjust it.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

Page 2 of 2 FirstFirst 12


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin