Kundo Kundo Electromagnetic

Discussion in 'Electric Horology' started by whatgoesaround, Oct 29, 2017.

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  1. whatgoesaround

    whatgoesaround Registered User

    Jan 22, 2008
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    Hello,
    I have a Kundo electromagnetic clock that just seems to have run out of power. It is the model that is basically a big white eight inch circle with a see through center on a brass base. I know the model also comes with the dial in black instead of the white. It has run quite well for years. Then recently it just quit. I figured the battery was the problem, so I changed it and went to wind some other clocks and looked over and it still was not going. It is just barely rocking back and forth, but not enough to engage the gears with the pallet. I checked the new battery and it is definitely good. Any ideas? Has the coil burn out? It is rocking back and forth under some power, but obviously far, far weaker than it should be. Thanks in advance for any ideas.
     
  2. John Hubby

    John Hubby Principal Administrator
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    Does your clock have mechanical contacts (they will be on the right side of the movement looking from the front of the clock) or does it have transistor switching? IF mechanical, I would say the problem is the contacts are dirty or burned from arcing. A photo of the front of the clock will show which it is. If it is one of the transistor versions then something is amiss in the circuitry.
     
  3. whatgoesaround

    whatgoesaround Registered User

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    Thank you, John. Well, I always learn something whenever you answer my questions. I have six different electromagnetic Kundos and none have the contacts on the side, like I see on my ATOs. I never knew they could come that way. So, it is the transistor type. The circuitry is hidden underneath the battery holder, that I would think, is not original. I had it next to an ATO and have learned that it is the ATO that was giving the little push to make this clock move so weakly (after it stopped). I would not have known the magnet in the ATO could be that strong; it does not seem to be rocking.
     
  4. Burkhard Rasch

    Burkhard Rasch Registered User
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    these KundO´s (without contacts) usualy come in two types: one with a switchboard in the base and the other where all electronic parts incl. the Germanium transistor is housed in the solenoid shell.The first ones usualy work while in the second type electronic failure is found more often.Hope Yours works again!
    Burkhard
     
  5. whatgoesaround

    whatgoesaround Registered User

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    Danke, Burkhard. Unfortunately, it looks like mine is the type with the transistor in the coil. I think the model was 825. I read that even if I could get the transistor, that it would be incased in steel, unless one of the originals, and would really affect the magnetic force. I saw online a guy that fixes the coils for $60+shipping. Maybe I can find a cheaper donor, but it sure seems that something is burnt out. I tested it and can register current through the circuit with the multimeter at 1000X ohms, but the arm is not moving.
     
  6. Berry Greene

    Berry Greene Registered User

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    What voltage is the battery in your Kundo?
    Don't over think this too soon. The usual problem is Verdigris in the supply wiring. Be certain that voltage reaches the circuitry if it is a transistor set up. Buzz out the wiring to make sure it's continuous. Has there been any damp? Condensation is a killer to copper & brass. BG
     
  7. whatgoesaround

    whatgoesaround Registered User

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    I am not even close to being knowledgeable about the electronics, but I used my multimeter on the 1K ohms marking and it made it through the entire circuit to make a reading, which indicates to me that the circuit is not shorted. No register on the X10 ohms setting. No corrosion. It seems I read somewhere a while back that the transistor is the likely culprit in these clocks with this circuit. I have looked online and found that the original transistor was a germanium transistor and hard to find, if I were brave enough to try to replace it. The coil wire is so thinv, it scares me a bit.
     
  8. Berry Greene

    Berry Greene Registered User

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    You can still get them even on ebay. Of course they aren't all new. See link below. Your best bet would be an OC71 or AC128. It's used as a switch so the characteristics ought not to be critical. Most transistors back in the daze were PNP types. Yes I can see that fitting it would be a challenge for anyone. However, for the small outlay it's surely worth a try. If you can't solder perhaps someone nearby could be found who can. Perhaps if you take the clock along together with the new transistor part.
    The transistor, the plastic bobbin and the fine wire are easily damaged by heat I will grant you. You have to be quick and use a heat shunt(s). A small spring loaded aluminium hair clip was ideal for use as a heat shunt. Strategically placed It absorbs the heat that runs up the wire from the soldering point. Of course both the coils need to be intact. You should be able to measure them with an ohmeter. You are looking for contiuity and not an enormously high reading in ohms. I wish I could be more specific but low kilohms is my guess. ( 1000 to 20,000R) OR 1K to 20K.
    BG

    germainium transistor | eBay
     
  9. whatgoesaround

    whatgoesaround Registered User

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    Thanks, I have located the number of the transistor and equivalents. I might be able to get one of the guys at our local tech college I am acquainted with to help me out.
     
  10. two sheds

    two sheds Registered User

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    Hello people

    I bought one of the more recent Kundo electromagnetic carriage clocks at auction (a friend is obsessed with electromagnetic clocks and a bit rubbed off on me). I think mine is an early version of the model (i.e. 1970s?) since there’s no pc board and I presume instead is a really sweet little switch that is closed every tick of the clock.

    It doesn’t work though and I’m no sort of watchmaker but would like to at least know what’s wrong. I’d like to download the instructions above to see how it works, but need a certain number of posts before I’m allowed. Should I post my questions one by one, possibly greeting everyone in individual posts until I’m allowed? I’ve got a couple of photographs if that would help.

    Thanks in advance
     
  11. Berry Greene

    Berry Greene Registered User

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    That sounds like an interesting clock and project. Please don't give up too soon. You have come to the right place. There are ways around most things. However we do need to identify the model etc. Start with some photos and we'll see if someone can identify what you have there. BjG
     
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  12. two sheds

    two sheds Registered User

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    Thanks :)

    I'll go and get photo - I hope I'm allowed to post it. From the first reply in the thread it does sound like the mechanical contacts that are at fault - I live in Cornwall so damp atmosphere.
     
  13. two sheds

    two sheds Registered User

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    Contact is at the right as I look at the front as John Hubby said up front of the thread.

    There's no pc board at the bottom of the clock. I have two very thin wires coming from the bottom, neither of which seem to be insulated unless there was an insulating paint that has rubbed off. I’m assuming the pendulum and coil body are one polarity and the back strut is the other. I get open circuit when I measure between the two which seems a good sign, and short circuit between the coil body and column at the back. Nothing that goes from open to short when the pendulum swings and the switch contact is made, though.

    I actually thought I was responding to a thread that gave pdf type descriptions of the clock so I'll go and look for them when I have the right permissions to download.
     
  14. two sheds

    two sheds Registered User

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    Oops I dragged and dropped the photo but it didn't work. Never mind, all adds to the post count :) Hope this works.

    Kundo mechanism.JPG
     
  15. whatgoesaround

    whatgoesaround Registered User

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    I am certainly not one speaking with any authority on this, but it looks as though the the two contacts on the right side are bent over and need to have space between the bar and these two contacts. As the pendulum swings the very top arm that is angled downwards should push on the top gear and it will end with the arm on the side of the movement jumping; it should just barely contact the two prongs on the side that end in gold plated tips. Currently, they look bent over and pressed against the portion of the arm that jumps, holding it down. You will see these parts moving in this video:
     
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  16. two sheds

    two sheds Registered User

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    I've taken a look and the contacts do look ok - it was a poor photo which may not have helped. I've added your notes to my Word document of "things to check", though. The contacts do look dirty though so I've ordered some switch cleaner on advice from another kind person from the site.

    I've downloaded all the pdfs of the clock and will give it all a good study and then start measuring resistances and poking around (very gently).
     
  17. Burkhard Rasch

    Burkhard Rasch Registered User
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    in this old thread Kundo - Kundo Electric clock You´ll find the original repair/maintenace instructions. Post 11 and following HTH
    Burkhard
     
  18. two sheds

    two sheds Registered User

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    Thank you, yes I've already downloaded them all :) And appreciated that you went to the trouble of uploading them originally - really helpful.

    I'm at the moment going through all my notes from the site, trying to get them in some order.
     
  19. Berry Greene

    Berry Greene Registered User

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    If it were me I would take out the battery, then connect an ohmmeter (switched to continuity or buzz if it has that feature) across the switch. Now operate the mechanism manually to close the switch and watch the meter or listen to the buzzer. That will tell you that the switch works and that it has low resistance contacts. They may be oxidised and you can try switch cleaner although almost any spirit (Isopropyl alcohol or methylated spirit) will probably loosen any deposit. However, you may need to wipe them carefully with what? I'd use brown paper or very fine abrasive paper. I mean fine and probably already used! The points are probably iridium or gold plate. If so they should not tarnish anyway!
    Be very careful with any fine wires from the coil. If they break its big trouble. You can measure the coil for DC resistance with the meter but I cannot advise you what that should be. If it's low voltage battery then it is likely to be quite low. {100- 1000R is just a guess}. However you are measuring DC and that's not what the circuit sees in operation because the coil acts like a balloon of magnetic energy. If he switch and coil seem reasonable you will need to check they are in a "circuit" - which is a ring with the battery connections. No battery yet.

    So now you're meter is on Volts with a battery installed. Your -ve probe is on the -ve of the battery and you are chasing the +ve around the circuit. When the switch closes it reaches the coil. A current flows, the coil becomes a magnet and attracts the pendulum. It's action switches the current off until the next time. That's what should happen!
    To check current you need to get the meter switched to mA in series with the flow. More difficult and I would use an external battery holder and croc clip leads. Every time that switch closes a current flows to energise the coil.
    That took a lot of words but actually its quite simple.
    Good luck and let us know how it goes.
    BerryG
     
  20. two sheds

    two sheds Registered User

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    #20 two sheds, Mar 10, 2019
    Last edited: Mar 10, 2019
    Great stuff, thank you. Have added that to my list of things to check. I'm still actually trying to understand how it works so what all the bits are for before risking doing anything - am getting there.

    I presume that the first toothed wheel has 60 teeth so moves the second hand. On that axis is a pinion (say with 10 teeth) which drives the next toothed wheel which also has 60 teeth. That would need another pinion with 10 teeth to gear back up to drive the hour hand?

    I can't quite see within the gubbins, but there looks to be a couple of extraneous toothed wheels and pinions driving the second and hour hands, which puzzles me a tad. Unless there's a 60-toothed wheel and a 10-toothed pinion with that pinion actually driving the hour hand.
     
  21. two sheds

    two sheds Registered User

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    I tried to edit that but my edit got rejected. So I'm going to need another wheel (say 20 teeth) and pinion (10 teeth) to actually drive the seconds hand because the pendulum swings twice a second. And the hour hand would actually need a pinion (10 teeth) and wheel (60 teeth).

    Sorry, my understanding *is* really this basic. :(
     
  22. Burkhard Rasch

    Burkhard Rasch Registered User
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    #22 Burkhard Rasch, Mar 10, 2019
    Last edited: Mar 10, 2019
    the KundO ´s never had a seconds hand , just hours and minutes.I don´t know the exact BPM rate of the KundO pendulum ,but You could check by moving the pendulum manualy back and forth for the minute hand to pass just one minute and count the number of movements , I´ll bet it is neither 60 nor 120 but something inbetween.HTH
    Burkhard

    I´ve just gone through the repair manual again,it writes the frequence is 1.5 per second or 10800 BPH
     
  23. two sheds

    two sheds Registered User

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    Yes minutes rather than seconds :oops:. I'll go and see if I can count some teeth :)
     
  24. two sheds

    two sheds Registered User

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    Hello again

    Well I’ve had a try but no success. I sprayed switch cleaner on the contacts and connected an Ammeter across all the places I can think of but can’t get a short circuit when the switch closes. It’s difficult because the moving arm of the switch is very delicate and I don’t fancy prodding it. I looked for a likely contact connected to it but nope. :(

    I may take it into a clock repairer to take a look and give me an estimate since I don’t want to fiddle when I don’t know what I’m doing. I can’t see a transport parking mechanism so I’m hoping that if I gently pack the pendulum with bubble wrap it will be ok? Thanks for all the posts though – very helpful and I do understand it better now. Lovely mechanism.

    One last thing on this though, I was trying to work out the gearing for the minutes and hours hands but wasn’t altogether successful there either. The pendulum does swing every 2/3 seconds. Its difficult to see but the am assuming the first and second pinion/gear teeth have ratio 45/6 and 72/6 which would give the 60 seconds. There are another two pinions/gears on the front that look like they have ratio 32/8 and 36/8 but that gives 18 hours which don’t work :( .Any thoughts?
     
  25. whatgoesaround

    whatgoesaround Registered User

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    Cleaning the contacts with the gold plated tips and the adjustment of the gap so that the bar just taps it are the two adjustments that have made the most difference for me on this model.
     
  26. no1bradd

    no1bradd Registered User

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    Hi im in thetfort norfolk do want the clock repairs i got a workshop in the back off the garage and i collect electrics clock .
    DSC00277.JPG
     
  27. two sheds

    two sheds Registered User

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    Hello bradd - thanks, I'll bear it in mind. I live in Cornwall but I could always package it up. The only thing is I don't know what's wrong with it. If it's the coil I'd imagine it would be expensive to rewind. I don't mind spending on it because it would be lovely to have it working, but I don't know whether I could stretch to coil rewinding.
     
  28. no1bradd

    no1bradd Registered User

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    Can you send me photo of it .
     
  29. two sheds

    two sheds Registered User

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    The mechanism is shown in post 14, and the clock looks like the one in post 15. I think it's an early model with a switch made/broken at the top right rather than a transistor. Thanks.
     
  30. no1bradd

    no1bradd Registered User

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    You can contact me no1bradd@hotmail.com send me some picture of back of the clock it should be like this .
    this the back of the clock with nothing in .

    DSC00247.JPG
     
  31. two sheds

    two sheds Registered User

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    This is the back of mine:
    arthur's Kundo.JPG

    I've in the meanwhile been having more success in tracing the electrical connections, and am hopeful I'll be able to see where the break is.
     
  32. two sheds

    two sheds Registered User

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    Hello again

    Progress :)

    I’ve traced the connections as far as I can. The major problem was that the wires going to the battery casing were insulated so I wasn’t getting a connection (they were so thin I couldn’t really see). So I burned off a bit of the insulation and soldered on a battery case.

    First question: does the polarity of the battery matter? Bearing in mind that there is (I think) no transistor, just a switch.

    I’ve not connected up the battery, but one side of the battery case now gives a resistance of about 1000 ohms through the body of the clock (and I presume the coil) right up to the contact pin which touches the dual-leaf gold-plated contacts every pendulum swing. The other side of the battery gives a short circuit to the metal clamp that holds the dual-leaf contact. So it looks like a good contact (nearly) all the way through :) .

    The resistance from battery case to the contact pin fluctuates between 600 and 1600 ohms as the pendulum swings – I presume because of the back emf in the coil. The voltage (no battery connected) varies between 160 to 200 mV as the pendulum starts swinging, gradually down to 0 mV as the pendulum stops.

    I’m now wondering whether @whatgoesaround was indeed correct that the two contacts on the right side are bent over, although the problem seems to be an open circuit rather than permanent closed circuit. Better photo attached. I'll do a short video if that helps.

    Kundo clock contacts.JPG

    I’m now presuming either the contacts are dirty (although I can’t see that and I did try cleaning them) or the pin isn’t contacting the gold plated tips at all. I can’t think of anything else that might be wrong.

    Thanks again for the help – I’m a lot more hopeful about this.
     
  33. two sheds

    two sheds Registered User

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    couldn't upload a video - I can't decide whether it shows the pin making contact or not. Perhaps will look at giving the adjustment screw a clockwise turn to see.
     
  34. whatgoesaround

    whatgoesaround Registered User

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    compare to the earlier posted video
     
  35. two sheds

    two sheds Registered User

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    Yours (top, image taken from your video) looks different to mine - I can't see the gold-plated twin contacts on yours. On mine the pin very nearly reaches the contacts but not quite - a friend suggested that I put a cigarette paper between them to see whether they were actually contacting, and it showed me that they weren't.

    Kundo reference mechanism.jpg

    Kundo clock contacts.JPG

    Sorry it seems to have doubled up on the attachments and I can't change it.

    Kundo reference mechanism.jpg Kundo clock contacts.JPG
     
  36. two sheds

    two sheds Registered User

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    It's working wehey :)

    I turned the adjustment screw one way and then the other and the contacts now make, and it's been going for an hour or so. :)

    So thanks again - I'd never have known how to approach it without the advice. Somewhat of a triumph - I've never been successful with anything like this before.
     
  37. two sheds

    two sheds Registered User

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    You may wish to have a bit of a quiet gloat at this point :)

    I'm glad I went through everything I did, though. I now do understand it a lot better.
     
  38. whatgoesaround

    whatgoesaround Registered User

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    I love the electromagnetics, too. No gloating, I am not very confident with these either. Congrats! on bringing it back to life!
     
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  39. two sheds

    two sheds Registered User

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    ta :) It's the only clock I have in the house and it's pleasant wandering downstairs and seeing it ticking away. I was surprised how small the swing is, I was expecting it to travel nearly the full magnet length.
     
  40. whatgoesaround

    whatgoesaround Registered User

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    Two Sheds,the electromagnetic Kundos I have swing so that the pointed end in the center swings from one end of the magnet to the other. Is it a good battery? Are the contacts where the battery goes clean?
     
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  41. two sheds

    two sheds Registered User

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    Interesting, thanks. I only actually have rechargeable batteries and I measured 1.3something V across it so that may be it. I'll get a non-rechargeable battery and see whether getting it up to 1.5 V makes a difference.

    It actually seems to be running just over a minute a day slow. I recall from my school physics that the maximum angle doesn't make any difference to the period as long as the angle's small. I presume the bell shaped thingy screws up or down to adjust the period, but I'll try a new battery before I try to correct it.

    It's still working though, tick tick tick :)
     
  42. whatgoesaround

    whatgoesaround Registered User

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    Ccrrect, it is not the length of the swing, DId the battery make any difference? Really, it is running, it is in range of adjustment (just a slight turn to raise the weight); sounds goodv enough to me. If the swing does not increase, you are still enjoying it, right? Enjoy.
     
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  43. two sheds

    two sheds Registered User

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    Yep still loving it, ta. It actually stopped after a couple of days but I'm hoping the battery wasn't fully charged. I put another one in two days ago and it's still going. It's only an AAA battery so I've bought an AA battery holder and non-rechargeable AA battery so we'll see. If it still runs down I'll assume I over adjusted the pin/contact so the pin is in contact for too long so it's draining the current.

    I did see from a data sheet that the clock only takes microamps but I presume that was for a transistor version. I think the coil resistance is around 1 kohm which with a 1.5 V battery would give 1.5 mA. Plucking a duty cycle of say 1/10 out of the air and an AA battery with say 3000 mAh, I'd hopefully get 20,000 hours or a couple of years.

    I live in hope. :)
     
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  44. whatgoesaround

    whatgoesaround Registered User

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    You only want a momentary contact
     
  45. praezis

    praezis Registered User

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    Conditions are even better: EMF reduces the voltage to 0.7 - 1 V.
    My comparable ATO takes avarage 35 µA.

    Frank
     
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  46. Berry Greene

    Berry Greene Registered User

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    While not wanting to be unnecessarily disagreeable or a right old clever clogs, I wonder if it would be better to work backwards from where you are. Can I take it that 3000mAh is a reasonable figure for the said battery? Then lets see how long it lasts. Wait and see. Expecting 2 years eh? From what exact type of battery? Is it fresh (newly manufactured).
    When inductors are in play - as they are here, the resistance becomes Z (not R) which is Impedance. That is for ac not DC. Because a field is produced - the BEMF back voltage that builds opposes the flow. When the field collapses you get some of your investment back! Useful if you know what to do with it. Put it in a big electrolytic capacitor perhaps? Another issue is the internal resistance of the battery which depends on the type and its condition. Lithiums in particular will often show a perfectly good off load voltage (light load as imposed by a decent measuring device (multimeter), BUT it will sag immediately you draw any current. Better for some circuit operation than others. It is very important to understand that.
    I was taught that very early on. A battery test must include a load. Preferably the actual load. Some modern meters include a battery test position that includes a load. There is a crude way that you can use a multimeter to test the relative "goodness" of a battery even if it has no such special battery test position. Switch it to high DC Amps (10A at least). Connect the probes briefly across the cell. (Only low voltage single cells please). Watch how far it climbs and how fast. Get to know your particular meter as each will give a different result. {Because shunts are not a standard). Don't overdo it or you will needlessly flatten the battery and heat up your meter shunt.
    You heard it here first? OK you didn't!
    Regards, BerryG.
     
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  47. two sheds

    two sheds Registered User

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    Sorry about the delay answering this, I didn't get an e-mail message alerting me to it.

    Yes I'm assuming a couple of years is hopelessly overoptimistic. It's been going a couple of weeks on an AAA rechargeable so far though :) . It's also only lost a minute in four days since I adjusted it. I'll see how long it goes for and solder an AA battery holder to it and see how that goes.

    One other question though. How can I adjust the time? So far I've set my alarm at the time the clock's reading and just started it then. Can I (gently) rotate the clock minute hand anticlockwise until I reach the right time?
     
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  48. MartinM

    MartinM Registered User

    Jun 24, 2011
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    This clock has no complicated strike or chime mechanisms with the associated cams and levers that would be a problem if the hands were turned backwards.
    Feel free to move it either direction.
     
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  49. Berry Greene

    Berry Greene Registered User

    Oct 2, 2017
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    If this is a clock that operates on a single cell, I would choose a primary battery every time as they give a little more terminal voltage. (1.5V). Rechargeable types such as Ni-Me-Hy & Ni-Cad are 1.2V through most of their discharge cycle. It seems small but is not so in terms of a percentage difference.
    Martin M is spot on wrt winding direction. However, if ever you have a mix of clocks that does include chimers and strikers some of which do not like reverse ACW setting, it's not a bad plan to cultivate a CW winding habit. You can even stop a clock for a little while and let time catch up then to avoid the awkward issue of resetting a few minutes of gain.
    Whatgoesaround makes a good point of enjoyment. In fact perfect clocks form only one strand of enjoyment. Sometimes the naughty character of some unpredictable mechanism is equally endearing and leads to more discussion and deeper thoughts than a really well behaved reliable clock promotes. The more you are called to attend it the deeper goes the ownership. That's been my experience anyway.
    Rgds, BerryG
     
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  50. two sheds

    two sheds Registered User

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    Yes I'm looking forward to trying to fiddling with it a bit to get the timekeeping exact. I will soon replace 1.2 V AAA with 1.5 V AA battery to see how that changes things. I'd imagine it would give a bit larger kick each period.

    I did also (for no apparent reason) work out from https://www.eeweb.com/tools/coil-inductance?utm_source=AspenCore&utm_medium=ELECTRONICS%20TUTORIALS

    with say 25mm average coil diameter and 3000? coils and 0.065mm wire diameter (AWG #42) that the coil inductance is around 1 H.So with 1 kOhm coil I get the time constant T=L/R seconds = 1/1000 = 1ms. So after 5 ms (5T) the current will have reached maximum value. With a 2/3 second swing, say the contact is made for 1/10 second or 100 ms so the rise time is negligible?

    As I say, the calculations were for no apparent reason :)
     
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