1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Electronically Impulsing a pendulum for a clock

Discussion in 'General Electronics Chat' started by markelectro, Apr 8, 2007.

  1. RODALCO

    RODALCO Well-Known Member

    Joined:
    May 21, 2006
    Messages:
    1,232
    Likes:
    43
    Location:
    Akld, New Zealand
    agent420 Interesting link re the maths for a pendulum.

    I knew the 2 * Pi * SqRt( L/G) formula which works out as near 1 metre for a clock with a one second beat.

    markelectro

    Better to have the pendulum rod a little longer than one metre than too short.
    The distance is measured from the suspension spring to about halfway in the pendulum bob. I would go for a 1.10 metre Invar rod with enough thread at the end to allowe for fine adjustment.

    The Hipp Toggle works on the attraction method and is very simple and minimises interference with the pendulum.
    It only closes the contact when the pendulum arc decreases enough to engage the v shaped pawl, to fall in the v shaped notch and close the contact briefly, energise the coils, attract the pendulum and keep it going for the next 20 swings or so.

    The Favag minute wheel rotates every 2 minutes, has 2 contact pins, one for positive impulse, one for negative impulse, for a full turn and is driven via a ratchet system from the top of the pendulum rod. I can take a few more photo's if you are interested.
    The Favag is designed for the European master slave clock systems, which usually run on 12 or 24 volts dc, with 1 minute impulses, and changing polarity every minute.
    My Favag runs within ± 2 seconds per week, which is very accurate.
    A solid wall is important too for mounting a masterclock, and not exposed in direct sunlight to avoid excessive temperature changes.

    The French Electrique Brillié system uses the alternating polarity system with changing polarity every 30 seconds, for a 1.5 Volts dc supply to the clocks.

    In case of the English 30 seconds single impulse slave clocks the minute wheel may be a 30 seconds wheel with 15 cogs and 1 contact pin, or a one minute wheel with 30 cogs and 2 contact pins.

    I have a Favag booklet somewhere in my archives and see if can find exact distances are for the position of the Hipp Toggle in comparison to the pendulum rod.
    For the 2/3 seconds beat i can measure it for you, but you are designing it for a one seconds beat, so i assume it will be within proportion, distance wise.

    If you are in the building stage and get excessive swing you can always reduce the voltage applied to the driving coil by inserting a resistance in series.

    Regards, Raymond
     
  2. RODALCO

    RODALCO Well-Known Member

    Joined:
    May 21, 2006
    Messages:
    1,232
    Likes:
    43
    Location:
    Akld, New Zealand
    A good little book to get is :

    Electric Clocks and how to make them.
    From F. Hope - Jones

    ISBN 0 85242 533 3
    From Argus Books
    14 St James Road, Watford, Herts, England.

    I bought it on Ebay USA for US$ 10.

    It discusses the Synchronome system in detail, as well as various clocks based upon the Hipp Toggle system.
     
  3. markelectro

    markelectro New Member

    Joined:
    Apr 17, 2006
    Messages:
    145
    Likes:
    0
    Location:
    Uk.
    Ray
    do Argus have a website.I would like this book.

    Regards Mark



     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. RODALCO

    RODALCO Well-Known Member

    Joined:
    May 21, 2006
    Messages:
    1,232
    Likes:
    43
    Location:
    Akld, New Zealand

    http://cgi.ebay.com/How-to-Make-an-...ryZ10026QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

    I bought it from this seller Chez Willy.

    The book i mentioned is not for sale at the moment, although i bought this book too which is also very detailed in electric clock building.

    Regards, Raymond
     
  6. agent420

    agent420 New Member

    Joined:
    Jun 1, 2006
    Messages:
    73
    Likes:
    0
    Location:
    3rd stoned from the sun
    I've been putting thought into this as well. The coil triggering method is dependant on the speed of the pendulum as it passes the coil; greater speed results in a higher voltage pulse and vice versa. As any of these cirucits are basically a comparator, triggering the impulse when a set voltage is reached, it is not enitrely location dependant; the pendulum speed will affect the trigger.

    Mechanical triggering may be more accurate in this respect, but then you have contact issues and the physical interaction of the pendulum and the switch... Still that system can work with high accuracy as commented by RODALCO about his Favag. More importantly, this shows how accurate a relatively 'simple' system could be, a fact that I think should not be underestimated.

    I have been thinking about using a sensitive Hall-effect sensor set for bottom dead center as the trigger. It should be location dependant only and not impart any physical interaction with the pendulum...

    Basically what you would be doing is simply calculating a delay time for when to start the impulse, based on the location trigger referred above. This would not necessarily have to a complex circuit, but it should be accurate and repeatable. Some delay time is always going to be required, as you will not want to send the impulse until after the pendulum has passed BDC.

    I think a sensor is a better indicator of position that attempting to calculate the pendulkum position. There are too many variables involved. The pic could calculate the required delay, however. You could also measure the pendulum accuracy by comparing measured triggers to a known higher reference, such the PIC's quartz oscillator. This information could then potentially be used in calculating the required impulse delay.
     
  7. RODALCO

    RODALCO Well-Known Member

    Joined:
    May 21, 2006
    Messages:
    1,232
    Likes:
    43
    Location:
    Akld, New Zealand
    Hi, bumping up this older thread.
    I have at the moment great success with impulsing and synchronising 2 Bürk masterclocks, and keeping them in perfect beat with an external oscillator.
    I will post some photo's in the near future.

    Basically i have added a brass nut with a steel nut araldited underneath the bob at the end of the pendulum rod.
    The brass M5 metric fine nut has the same thread as the pendulum rod ( just easier to tap brass than steel ).
    I stripped an old relay contactor assembly and rewound a new coil on it (approx 30 ohms)
    Made supply ± 5 to 7 volts not critical because CMos IC's are used.
    Oscillator provides 1 second pulses.
    via 4N35, 4017 and 4508 i decode an impulse every 3 seconds so it can drive 1 and 3/4 second clocks as well.
    I have off set the coil underneath the 3° mark and it locks in perfectly.
     
  8. Rolf

    Rolf Member

    Joined:
    Jun 22, 2006
    Messages:
    655
    Likes:
    8
    Location:
    E. Tennessee, USA
    Kiss!

    Great! Looking forward to seeing the pictures.
    Your success with this project confirms my belief in KISS (keep it simple stupid) :)
     
  9. markelectro

    markelectro New Member

    Joined:
    Apr 17, 2006
    Messages:
    145
    Likes:
    0
    Location:
    Uk.
    Rod
    I will second that!! looking forwards to seeing photos and diagrams maybe. My initial posted request was to try and impulse without any hipp/toggle to trigger the impulse, I wanted to impulse using sensors and PIC'S but do you know I think that this would not look half as nice as the many types of hipp/toggle options available, give me something to look at.

    http://www.electric-clocks.nl/clocks/en/index.htm

    Rod can't wait to see your results, regards Mark
     
    Last edited: Jun 21, 2007
  10. RODALCO

    RODALCO Well-Known Member

    Joined:
    May 21, 2006
    Messages:
    1,232
    Likes:
    43
    Location:
    Akld, New Zealand
    Pendulum synch cct

    Hi, I have attached a simple circuit which works well, in XL format.
    As i have no drawing circuit drawing prgramme, the symbols used for coil etc have been improvised as blocks with text inserted.

    All resistors are 1/4 watt, diodes are small signal diodes. Depending how heavy the pendulum is some experimenting with more coil turns or other voltages may be required.
    I run it of a variable supply, between 5 and 8 volts seem to work best.
    The C mos ic's should work reliable between 5 and 15 Volts dc.
    The Bürk 3/4 second pendulum bob is about 800 grammes at 60 cm invar rod.

    I put also a blue LED in parrallel with the coil so i know if all is in step.

    The 1 second clock circuit i can post if you need it.
    I is taken from an old powerboard QTT quartz clock used in the utility industry.
    These use a 4.19MHz crystal and divide by 22 IC. and drift is less than 2 seconds a month.

    Drop me a PM if you need the XL sheet.

    Now get the links to the photo's sorted at photobucket.
     

    Attached Files:

  11. RODALCO

    RODALCO Well-Known Member

    Joined:
    May 21, 2006
    Messages:
    1,232
    Likes:
    43
    Location:
    Akld, New Zealand
  12. Rolf

    Rolf Member

    Joined:
    Jun 22, 2006
    Messages:
    655
    Likes:
    8
    Location:
    E. Tennessee, USA
    That is a fantastical simple circuit and pendulum swing correction setup.
    Question: What was the clock accuracy before? Just trying to get some idea of how much it is able to "pull" it into sync.
     
  13. markelectro

    markelectro New Member

    Joined:
    Apr 17, 2006
    Messages:
    145
    Likes:
    0
    Location:
    Uk.
    Ray fantastic stuff!!

    Very interesting to see it being used.I would be pleased to see the 1 sec circuit has I have 1 sec clocks.

    I will try and re-create the diagram in Livewire (a circuit drawing pro) or at least I will try as not got my head totaly around it yet.

    Regards Mark
     
  14. markelectro

    markelectro New Member

    Joined:
    Apr 17, 2006
    Messages:
    145
    Likes:
    0
    Location:
    Uk.
  15. RODALCO

    RODALCO Well-Known Member

    Joined:
    May 21, 2006
    Messages:
    1,232
    Likes:
    43
    Location:
    Akld, New Zealand
    Bürk masterclock

    That Bürk ¾ sec. master clock runs better than ±15 seconds per month.

    Even by wrongly adjusting it, so it gains / looses one minute a day, this circuit will keep the clock in synch.

    With a one second pendulum bob which is heavier you may have to experiment with more turns on the coil to get enough pull but the basics are still the same.

    I like using standard components which are usually more reliable than PIC's and don't suffer from data loss.

    My main purpose for this circuit is to keep two master clocks next to each other, having the penduli in exact swing with each other.
     
  16. markelectro

    markelectro New Member

    Joined:
    Apr 17, 2006
    Messages:
    145
    Likes:
    0
    Location:
    Uk.
    Ray you will have to explain the theory.Just how???

    So set the coil to charge every 3 secs???Have you thought of a trigger method by using sensors or is this not required??

    I completely understand and I will try and recreate your method.


    with this Is it a simple case of both clocks are using the same type of impusing so sould be in sync??

    Keep up the good work mark
     
  17. RODALCO

    RODALCO Well-Known Member

    Joined:
    May 21, 2006
    Messages:
    1,232
    Likes:
    43
    Location:
    Akld, New Zealand
    mark,

    By lowering or highening the pendulum bob you can make a clock run slow or faster.
    To check how well the circuit works i purposely lowered the bob to make the clock loose 1 minute a day.
    The circuit will keep the pendulum "locked in" with the external crystal oscillator and run correct. when turned off the clock will loose time again ( 1minute/day).

    I choose the one in three seconds. You can easily change it to one in 6 or 9 or any combination. The three corresponds to a multiple of ¾ seconds to get a synch.

    With a one second you can try one or any multiples of one.
    With a 4017 you simply have to connect the reset pin to the division required.

    No external sensors are used.
    The impulse will increase, decrease any minor errors in speed between the pendulum bob and synch circuit.
     
  18. markelectro

    markelectro New Member

    Joined:
    Apr 17, 2006
    Messages:
    145
    Likes:
    0
    Location:
    Uk.
    Ray
    Going back to the parts.You used an old contact relay for the electro magnet pulse.Have you any thoughts on constuctiing one of your own?I you have any info I would like to hear.

    Regards Mark
     
    Last edited: Jun 26, 2007
  19. RODALCO

    RODALCO Well-Known Member

    Joined:
    May 21, 2006
    Messages:
    1,232
    Likes:
    43
    Location:
    Akld, New Zealand
    Relay former

    Mark,

    I used the old relay E shaped former for the magnetic field.
    (This was an ex streetlight contactor from the POCO i work for, which was open circuit)
    These relays or contactors have two E slapes which close when ac is put on the coil.
    I only use one E shape of the latter.
    The other E shape is used for the other clock coil.
    The original coil was stripped of all it's wire and than cut in half to make the coil fit on exactly one half E former.
    I glued an other end piece on the half coil to make it as a bobbin.
    Then used my handwinder built from Meccano and put on about 300 turns of thin wire ( haven't got a gauge ) but wire i have a big reel off.

    I'm making another coil for another experiment and will take photo's as i progress.

    Kind regards
    Raymond
     
  20. markelectro

    markelectro New Member

    Joined:
    Apr 17, 2006
    Messages:
    145
    Likes:
    0
    Location:
    Uk.
    Ray
    Cheers!!
    always good to make use of spare parts.

    Looking forwards to the progress.

    Regards Mark
     
  21. markelectro

    markelectro New Member

    Joined:
    Apr 17, 2006
    Messages:
    145
    Likes:
    0
    Location:
    Uk.

Share This Page