European Electric Clock 50 Hz

Discussion in 'Electric Horology' started by dalesr, Jan 12, 2009.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    I have an old European Electric Synchronous Motor Clock that was built around 1940 by my father. It was running at 110 Volts at 50 Hz with no earth ground or fuse. I have grounded this clock and fused it. However, this clock is running fast since it is running at 60 Hz and the gear train was designed for 50 Hz. I would like to convert this clock to run at 16 volts AC to make it safer per an article from Rod Elliot,who I believe is a member, by creating a new coil with the appropriate turns to have this motor run at this safer voltage. I will then purchase an UL approved 16 volt AC power pack. I will still have the problem with the frequency since this clock is designed to run at 50Hz. I am looking for a way to make this 50 Hz clock useable at 60 Hz using my 16 volt AC Power pack as the power supply. Rod Elliot stated that he was planning on writing another article on how to convert a 50 Hz clock to run on 60Hz. I am anxious to find out if this article is still in the planning phase but have no way of contacting him. Any help on this would be greatly appreciated even if there are other ideas on how to convert this clock to run at 60 Hz and keep accurate time. I want to keep this clock as orginal as possible since it was customed made.
     
  2. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    Converting a synchronus AC electric clock from 50 Hz to 60 Hz use generally involves reducing the tooth count of the pinion on the fastest running part of the clock; usually the motor pinion. It is a practical method and depends on the skill of the clockmaker and availability of a pinion of the same size dimensions but with fewer teeth.

    The other method would be to alter the number of pole pieces on the clock motor; something possible but impractical and I've never heard of anyone doing it.

    I understand a recent discussion about the safety of using mains connected old electric clocks. Fusing and grounding techniques only help if the alterations are done with care and understanding. Rewinding the motor coil with bigger wire and using a lower voltage may satisfy certain needs but in my view does not make an electric clock safe to use from a fire and safety view.

    To my knowledge, the European Pujol clock is the single outstanding clock with a reputation for setting fire to homes.
     
  3. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    So even if I used an UL approved 16 VAC power supply where the current draw is under 15ma, you still believe this is a fire hazard. I am interested in understanding why you feel this still is a fire hazard. I want to be sure I fully understand my risks and appreciate your input.

    The pinion closest to the motor will be difficult to match and I am not even sure where to start looking for this part. Do you have any ideas where I can find electric clock pinions for old electric clocks? I could take pictures of this pinion if this would be helpful.
     
  4. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
  5. harold bain

    harold bain Registered User
    NAWCC Member Deceased

    Nov 4, 2002
    40,850
    162
    63
    Male
    deceased
    Whitby, Ontario, Canada
    Country Flag:
    Region Flag:
    Hi, dalesr, welcome to the message board. Does the clock you have use a telechron motor similar to the one pictured in your article? If so, it is possible to get a replacement rotor (the rotor, not the field, controls the motor speed). Fusing the motor is not a bad idea. What size fuse are you using? I would go with about 1 amp, as these motors do not draw much current.
    I have worked with rotors and fields for about 40 years and have never seen one overheat to be a danger of catching fire. The field itself seldom causes any problems, but the warnings of old wire insulation are quite valid. As for grounding, have you noticed that plug in lights are seldom grounded?
     
  6. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    The subject of the thread was about a clock your father made that you want to operate on 60 Hz mains. You stated that you have "grounded this clock and fused it." Nobody is going to fault your action.

    And I thank you for the reply to my comments about making old mains powered electric clocks safe from causing house fires or electric shock to users. However, that's another subject and has to be addressed with considerable care.

    I have browsed Rod Elliot's article and understand the intent and thrust of his procedure. I feel that commenting on this venue about electrical safety in very specific terms such as recommending certain procedures and using specific electrical products would be like "walking thru a mine field."

    Back to the thrust of your query: it would be helpful if you would describe the clock and include photos of the motor. It is likely that if the clock rotor is one made in the US, one of the contributors would provide a source for a suitable pinion to reduce the speed of your clock so as to operate from 60 Hz mains.
     
  7. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    More: For European made AC electric clocks, the old Rudof Flume clock parts books list various fiber gear/pinion gear sets for Junghans, Urgos, Petersen, Mehne, Mauthe, KundO, Muller, Kienzle etc.etc. The dimensions of the gears and pinions and tooth counts are given. Rotor specifications are also provided. Because you stated your father's clock was made in Holland, it may have a German motor.

    Photos and description of the motor in your clock with the data in the Flume catalogs may assist in deciding a way to re-gear your clock for use on 60 Hz.
     
  8. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    I have this clock protected by a fuse of 250ma. The current draw on this clock measures 14.26ma. The VA is (14.27ma)(115) = 1.64 watts
    The DC resistance measured on the coil is 3.8K ohms and the calculated XL is 115/14.27ma which is 8058 ohms. I am ground this unit to earth ground because there may be a potential where the coil bobbin may short to the laminated core. I believe this is very unlikely but just an extra precaution since the enclosure is metal. Attached are pictures of the clock and motor. I believe this gear train was made in Holland. This clock dates around 1942 right after the war. It was very hard to get copper during those times so it was built with metals available at that time which my dad said was zinc and brass. This clock works fine and has a mechanical display for Date, Day, and Month. I hope someone has an idea on how to get this clock to keep accurate time within a budget.

    Attached are pictures of my clock.

    Picture 076.jpg

    Picture 077.jpg

    Picture 080.jpg

    Picture 084.jpg
     
  9. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    Your photo (84) of the back side of the movement strongly resembles the Urgos 11, probably an earlier version. The three terminals on the bobbin is suggestive of dual voltage ie: 110/220.

    Re-gearing the works for 60Hz use will require a count of each wheel and pinion and including the rotor and calculation to determine a practical change of pinion to slow the hands.
     

    Attached Files:

  10. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    Les,

    Thanks for the quick response on this and finding the manufacturer of this motor. The gear train also has a worm gear and not sure how to include this in the wheel and pinion count. This may take me a while since i have to dissemble the gear train and identify each wheel and pinion. I will make a drawing of the gear layout including worm gear. This is a nice project.

    I really appreciate you finding this information for me and providing me this technical knowledge. My dad had this clock sitting around for over 50 years after he immigrated to the Unites States.

    Also, how do I identify how many poles are in this motor. I thought this was a single phase synchronous 2 pole motor. However, the calculations used to calculate the speed of the motor would indicate that this motor is running at 3600 RPMs. I do not believe it is running that fast which makes me believe there are more than 2 poles to this motor.

    RPM = (f * 60) / (n/2) where n is the number of poles.

    -Ray
     
  11. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    The synchronus motor in your photo appears to have 40 poles and would turn 150 rpm at 50 Hz or 180 rpm at 60Hz.
     
  12. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    Thanks for letting me know the number of poles/speed of this synchronous motor. Since you were able to figure this out from the picture I sent you, do I just count the number of teeth/magnets on the rotor to determine the number of poles?

    I will be working on the wheel count and pinion count including the pinion count on the rotor this weekend. The wheel that connects to the pinion on the rotor is made of plastic and all of the other gears are made of metal. This plastic wheel has a shaft on both ends and is easily removed once I dissemble this gear mechanism. I already did this once to clean and then oil the pivot points on this assembly. I plan on creating a drawing with the teeth count on both pinions and wheels which will include the diameters of the pinions and wheels in this gear train. I plan on having this done by Monday. I will be using Visio 2007 since that is the only drawing software I have. I will create a PDF file to upload this drawing into this message board. I hope that is okay.
     
  13. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    Good plan!

    I'm sure a sketch of the wheels and tooth counts will reveal that the part you need to change is the wheel/pinion pair driven by the pinion on the rotor. Although there's a possibility that a rotor with more poles too could be a practical change.

    Note that the "plastic" wheel driven by the rotor is most likely one generally referred to as a "fiber" gear wheel. They were made of linen cloth/bakelite composition and are very fragile.

    Additionally, most of the pivots in an electric clock are usually lubricated with grease not oil. Most agree on this point. The reason is because unlike spring or weight driven clocks, with gear-up ratios, AC electric clocks have gear-down ratios. Too, it is common to lubricate the gear teeth, something ill advised with spring/weight clocks.
     
  14. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    I lubricated the pivots using clock oil and did not lubricate the gears. I am glad you brought that point up. Is there a special type of grease recommended for lubricating electric clocks? :eek:
     
  15. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    Grease for electric clocks should be a good grade and not thick, not thin. I doubt that Vaseline is appropriate....more like ball bearing grease compounded from rapeseed oil.

    I'm sure some clockmakers would use their favorite mainspring grease.
     
  16. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    The attached drawing provides the wheel and pinion count including the diameters of each wheel and pinion. The measurements were made using a Fractional Dial Caliper and all measurements are in millimeters. There are thirty poles on the rotor and the calculated motor speed at 50 Hz is 200 RPM and the calculated motor speed at 60 Hz is 240 RPM. I have made an attempt to figure out the speed at each phase starting at the Rotor Pinion and ending my calculations at the Minute Wheel. My calculations were based on 50 Hz just to make sure that the wheel and pinion counts are correct. I believe my numbers are accurate since the Minute Wheel has 72 Teeth and the calculated RPM at 50 Hz was 1.25 RPM. The ratio 60 minutes/72 Teeth equals 0.8 and the factor of 1.25 times 0.8 equals 1 RPM. I then worked backwards and made an attempt to calculate the number of teeth at each phase to have this clock run at 60 Hz. I have identified three places that can be changed to have this clock run at 60 Hz as shown below. I have attached a picture of these electric parts.

    1. Another Rotor with 36 Poles
    2. New Minute Wheel from 72 Teeth to 90 Teeth
    3. New Worm Wheel that is mounted on the Plate from 40 Teeth to 48 Teeth

    Based on my calculations, the Fiber Gear Wheel that connects to the Rotor Pinion cannot be modified unless both the Rotor Pinion Teeth and the Fiber Gear Wheel Teeth are changed. Therefore this was not an option in correcting the clock to run at 60 Hz.

    Please review my drawing and my calculations and let me know what would be the easiest way to get this clock to run at 60 Hz. I was leaning toward the Minute Wheel Gear since it looks like this gear can be removed with the right tools and replaced with a new wheel with 90 Teeth. However, I was not sure if that many teeth on a gear are recommended and will this work with the worm gear that has 9 threads.

    Thank you so much for taking the time to work with me on this project. I have already learned so much and I am very interesting in learning more about clocks.
     

    Attached Files:

  17. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    I've studied your excellently prepared analytical drawing of your 50Hz clock movement.

    I agree with your conclusion of a practical conversion to 60 Hz operation would involve replacing the 75 tooth minute wheel with one made with 90 teeth.

    I had thought that a simpler change would involve either a change from a 30 tooth rotor to one with 40 poles might be easier or replacing the pinion.

    I opened a generic US made 60 Hz "spin-to-start" electric clock to count the rotor. It has 36 poles! Obviously a different design completely.

    Again, your drawing is excellent and is commendable.
     
  18. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    I am not sure what to do next. Who would be able to assist me in determining if I can replace this gear with 90 teeth and what the cost would be? I would imagine that the person doing this work would need the shaft that this gear exists on as well as the plate where the worm gear is mounted.

    Thanks for the compliment. I wanted to be sure that you had enough detail to determine the best approach to resolving this.
     
  19. swolf

    swolf Registered User
    NAWCC Member Sponsor

    Nov 24, 2002
    395
    1
    18
    MA
    Country Flag:
    The ratio ofn a pair of worm gears is determined by the number of teeth in the toothed gear divided by the number of spirals in the worm.

    Number of teeth in gear = ratio of the two gears.
    number of spirals in worm


    Sherm
     
  20. clock works

    clock works New Member

    Jan 18, 2009
    3
    0
    0
    Hello,
    Have you thought of generating the AC 220V 50hz? It may be easier than cutting new gears.
    http://www.elmelectronics.com/index.html sells an IC ELM446DS that will putout 50Hz from commonly availabe 3.58Mhz TV colour burst crystal.
    All you have to do is input that signal into a low power car audio amplifier and connect the output to a secondary of a small transformer (220V in 12V out). If there is a bit of hum, then use another two more tranformers to step down and step up. In that case first two transformers can be 110V to 12V.
    If you can find the transformers (by taking them out of the DC wall power supplies that have some iron inside), 12V DC power supply, and the amplifier on Ebay you could build one for about 50 Dollars.
    http://cgi.ebay.com/Stereo-Hi-Fi-Audio-Amplifier-Car-Motorcycle-Boat-Radio_W0QQitemZ180321913678QQihZ008QQcategoryZ18795QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
     

    Attached Files:

  21. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    My original plan was to do this electronically and make this clock electrically safe. I found the attached URL that explains in detail how to modify the coil to run at 16 VAC using a standard UL Approved 16 VAC power pack . This author is planning on writing another article on how to convert a low voltage (16 VAC)@ 60 Hz to 16 VAC @ 50 Hz. I am not sure when he will write this article. The ELM446 digital divider integrated circuit seems like this would work well with a coil running at 16 VAC. Could you provide me a schematic using a 16 VAC@60Hz with an output of 16VAC@50Hz using the ELM446? See the article below for more details on converting the clock from 220 volts to 16 VAC.

    http://sound.westhost.com/clocks/ocm.html

    I was hoping that I would be able to just replace a gear. However, this now looks like it would be more difficult and costly and I do not want to spend that kind of money on this clock.

    Thanks for the input.
     
  22. clock works

    clock works New Member

    Jan 18, 2009
    3
    0
    0
    If it isn't broken, don't fix it. Rewinding the stator is as much involved as making a new gear. My solution provides enough isolation (electric shock hazard) through the transformers and if you use a .5A fuse to the audio amplifier, then your clock has fire protection as well.

    If you still wants 16V the you could add another step down transformer 220V to 16V. The more the number of transformers used, the harmonics will be less and the motor will run smooth and quiet.

    Providing quartz referenced 50Hz is expensive and not easy. If you have some soldering skills you could put that IC onto a perforated PCB and stuff it inside the amp. You could use a 3pin 5V regulator to power the IC which may be already availabe inside the amp.

    This method preserves the clock as it is if in case you want to use it in Europe.
     
  23. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    I agree with you 100% that if it is not broken don't mess with it. The clock is running fine at 60Hz but fast as expected because gear train is designed for 50 Hz. I am not sure I fully understand your design and how the harmonics will be less because of more transformers. Can you provide me a schematic using your design and an explanation of how the harmonics will be reduced and make the clock run smoother? This will help me visualize and better understand your design. FYI, The coil on this clock supports both 110 and 220 and the current draw at 110 volts is 15ma. I currently have a 250ma fuse installed on the hot side and the unit is now grounded. The clock is a metal chasis.

    Also, is there a problem using an existing power inverter with a modified sine wave. I found this power inverter and it costs about $30 but not sure if the modifed sine wave will work with clock motor. I am assuming a modified sine wave is a square wave. Is a pure sine wave recommended for the motor to run smooth/quiet/reliable?

    http://www.dvdoverseas.com/store/index.html?loadfile=catalog91_0.html

    Thanks for the input and quick response.:)
     
  24. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    AC electric motors are designed to operate within a narrow range of frequency (Hz) generally 50 or 60 Hz. Too, the AC waveform is sinusoidal.

    Square wave AC or stepped square wave AC or modified square wave AC has, by nature, a very high frequency component....approaching infinity. Some filtering using inductors or transformers does remove or further modify the square wave by reshaping the square into something approaching a sine depending on the complexity of the filter. In so doing, even harmonics of the fundamental waveform may be introduced along with the modified waveform at reduced amplitude.

    Harmonic components in the supplied AC power result in heating of the iron core material of the AC motor in much the same way as higher frequency AC. The same applies to transformers. Special iron, sintered or finely laminated is needed for core materials higher than 60 Hz; ferrous material that can magnetize and demagnetize or change state rapidly. Plain iron can't; it just gets hot and current goes up making more heat loss in the copper windings.

    I personally would not recommend providing synthesized alternating current for a clock or small motor designed for low frequency AC except on an intermittent basis.
     
  25. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    This was very informative and answers my question that the power inverter is not a good idea. What possible solutions do I have to get this clock to run safely/reliably at 50 Hz without damaging the motor using a 60Hz line voltage? I know that the gear change would work to run at 60Hz but not sure if I can find a gear of 90 teeth that will mesh with the worm gear. Nor would I know how to install this gear if I found one. I do believe this is the best approach though.

    I loaded this free software from the web called emachineshop which provides estimates for gears. I put in the specifications for a 90 gear with the diameter specified in my drawing and the price was around $200. Ouch!!!

    http://www.emachineshop.com/machine-shop/index.php

    This clock also moves a mechanical Dutch calendar and the hour shaft is specifically designed for this mechanical device. So it seems that my only choice is to use the existing gear train with it modified to support 60 Hz, right? Where do I go from here?
     
  26. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    Changing the 75 tooth worm wheel to a 90 tooth wheel is, in my opinion, not satisfactory unless the worm shaft is also changed to match the pitch of the 90 tooth replacement wheel.

    A more "forgiving" place to change ratios, I believe is at the first reduction where a ten-tooth pinion drives a 40 tooth wheel. Replacing the ten tooth pinion with one of 12 teeth would, I'm thinking cause the 40 tooth wheel to rotate at the designed rate.
     
  27. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    #27 dalesr, Jan 21, 2009
    Last edited: Jan 21, 2009
    I like the idea of replacing the pinion since this is the most forgiving place to change the ratio. I am not sure how changing the pinion to 12 teeth makes the 40 gear rotate at the right rate. Based on my drawing and calculations, I thought that the 40 Gear must run at 50 RPM. When I use a 12 tooth pinion, I am calculating 72 RPM. Am I doing this wrong? Please advise.

    W(A) = 10/40 * W(B) = 1/4 * 200 RPM = 50 RPM assuming clock is running at 50 Hz
    W(A) = 10/40*W(B) = 1/4 * 240 RPM = 60 RPM
    W(A) = 12/40 * W(B) = 3/10 * 240 RPM = 72 RPM

    If the 40 Gear wheel driving the 10 gear pinion was changed to 48 gears, the RPM would be 50 RPM based on my calculations.
    W(A) = 10/48 * W(B) = 5/24 * 240 RPM = 50 RPM
    However, this gear is on a shaft that has threads that drive another gear and not sure if this fiber gear can be replaced easily. This is assuming that my calculations are correct.

    Thanks for the input;)
     
  28. harold bain

    harold bain Registered User
    NAWCC Member Deceased

    Nov 4, 2002
    40,850
    162
    63
    Male
    deceased
    Whitby, Ontario, Canada
    Country Flag:
    Region Flag:
    Dale, can you post a few pictures of the motor itself? Just wondering if there may be any North American equivalents that may fit.
     
  29. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    Harold,

    I posted the pictures of the motor and clock on 01-13-2009, 08:31 PM. It was post # 8. I am not sure how to link this post to this thread. Is this what you are looking for?

    Thanks

    -Ray;)
     
  30. harold bain

    harold bain Registered User
    NAWCC Member Deceased

    Nov 4, 2002
    40,850
    162
    63
    Male
    deceased
    Whitby, Ontario, Canada
    Country Flag:
    Region Flag:
    Dale, I didn't realize that whole assembly was the motor. I thought that was the whole clock movement.
     
  31. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    It is the motor and clock movement. The motor is the front view which includes the coil, laminated core, and rotor. The rotor has a pinion that connects to the clock movement. It looks like I would need to replace the whole assembly (motor and clock movement) to run at 60 Hz. This would have to mate to the mechanical calendar which is also shown on post #8. The hour shaft is a bit longer so it can pass through the mechanical calendar and then attach the minute and hour hands. The only other options discussed thus far are finding a rotor with 36 poles that is identical to my existing rotor except the old one has 30 poles. Les was hoping that would be the case since it is the simplest solution. The other options include gear/pinion changes which we have been discussing and still finalizing best approach from a technical and cost perspective.

    If I can find a motor/clock movement at 60Hz and retrofit this into the mechanical calendar, that would be nice. This way I would not have to worry about gear changes and this clock could be used in different frequencies by just replacing the motor/clock movement.

    I really appreciate everyones input. :)
     
  32. fixoclock

    fixoclock Registered User

    Aug 29, 2000
    138
    5
    18
    Male
    Country Flag:
    Rod Elliot is a member of Chapter 72, Sydney Australia. He is our in-house expert on all things horologically electric.
    Contact him via email at : rode@sound.au.com

    I personally have rewound two 240VAC 50Hz synchronous motor clocks to operate on 16VAC according to Rod's instructions and they run cool, and are intrinsically safe "low voltage" by the Australian Standards.

    Lindsay Bramall.

    ps. Les, the AMCC electric 4-glass regulator is running perfectly.
     
  33. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    Lindsay,

    I will reach out to Rod Elliot.

    Thank you:)
     
  34. RodE

    RodE New Member

    Aug 20, 2006
    2
    0
    0
    Electronics Engineer
    Sydney, Australia
    Country Flag:
    Region Flag:
    For those who have shown an interest in the frequency changer, the article is close to completion. Be warned though ... it is based on electronics from start to finish, so some may need to involve a friend to assist.

    I have to construct a prototype system to do a complete test, because there are several sections that cannot be acceptably verified using theory alone. This will take me a while, as I'm pretty busy at the moment.

    No conversion system like this is trivial, but the one I have developed is designed to track the mains frequency perfectly, which should give the most accurate timekeeping possible. As far as I'm aware, the technique has never been used before for this application.

    The nice part is that there are no potentially irreversible changes to the clock train, so originality is easily preserved (provided you retain the original 120/220V coil intact - highly recommended where possible.

    Even commercially available quartz crystal based systems with 1ppm (part per million) accuracy (which is considerably better than the normal) will give an error of a couple of seconds per month. The mains is usually better than this by at least an order of magnitude long term.

    Regarding the safety issues with using mains clocks with unearthed Class 0 insulation (known in regulatory circles as "basic" insulation), this is either now banned or is being phased out worldwide. Double insulation standards do not apply to any clock motor I've seen.

    Class III (SELV - Safety/Separated Extra Low Voltage) is generally considered to be intrinsically safe, and SELV transformers that are VDE, IEC, CSA, UL (etc.) approved are almost always double insulated, and must satisfy stringent requirements regarding safety during fault conditions, both internal and external.

    As Lindsay indicated above, my email is mailto:rode@sound.au.com and all queries are answered as long as my email address is allowed past your anti-spam filters.

    Cheers, Rod

    http://sound.westhost.com/clocks/
     
  35. fdew

    fdew Registered User

    Jul 12, 2007
    233
    4
    18
    How about a outside the box solution to both problems. As I understand it this is a spin start movement and the wiring may be suspect. connect a gear to the spin start shaft, buy a proper speed AC synchronous motor install a mating gear, make us a bracket, and plug it in. Nothing in the clock is damaged, and it runs.

    Frank
     
  36. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    Rod,

    I sent you an email

    -Ray
     
  37. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    Frank,

    Thanks for the input. The spin start level starts the rotor manually and not sure how the gear would mate with the rotor poles.
     
  38. eskmill

    eskmill Registered User
    NAWCC Fellow NAWCC Member

    Aug 24, 2000
    7,135
    31
    0
    Region Flag:
    Dalesr has determined the most practical way to convert his European made 50 Hz AC synchronus motor clock to operate on 60 Hz is to replace the 30 pole rotor with one made with 36 teeth.

    Hopefully someone can locate a 36 pole rotor having a ten-tooth pinion that will fit the dimensions he's made of his 30 pole rotor. Its OD measures 28mm with a 10-tooth pinion having an OD of 5.5mm.

    A page showing available European electric clock rotors is in the snapshot below. Presumably made for 50Hz. Note that none are listed in the catalog page with 36 poles.
     

    Attached Files:

  39. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    Les,

    Thanks for posting the specification sheet for my rotor and requesting a search for a 36 pole rotor.

    Greatly appreciated!!

    -Ray
     
  40. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    [FONT=&quot]This old electric clock also needs a minute hand and nut. The hour hand dimensions are 1.5 inches long from center hole to end and the inner diameter is 5mm. See attached picture. I am looking for a pair of hands that will look similar to this hand. The minute hand I am figuring is about 2 inches long and it is oblong. The dimension for the shaft for the minute hand is oblong and is ~ 2.5mm or 0.14 inches. There is also a thread to hold the minute hand in place. This is a very fine thread most likely metric and the diameter is about 2mm or 0.12 inches. Does anyone have an hour hand and minute hand with mounting nut that resembles this hour hand?[/FONT]


    file:///C:/DOCUME%7E1/Dalesr.JSQ/LOCALS%7E1/Temp/moz-screenshot-2.jpgfile:///C:/DOCUME%7E1/Dalesr.JSQ/LOCALS%7E1/Temp/moz-screenshot-3.jpg HourClockHand.GIF [FONT=&quot][/FONT] [FONT=&quot][/FONT]file:///C:/DOCUME%7E1/Dalesr.JSQ/LOCALS%7E1/Temp/moz-screenshot.jpgfile:///C:/DOCUME%7E1/Dalesr.JSQ/LOCALS%7E1/Temp/moz-screenshot-1.jpg
     
  41. dalesr

    dalesr Registered User

    Jan 4, 2009
    225
    1
    18
    New Jersey
    Country Flag:
    I have found a minute hand.

    I think this forum can be closed

    Thanks for all of the help.

    I want to specially thank Les for all of his help on this clock.;)
     

Share This Page