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Clock wiring

John Wilding's version of the Murday clock

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John Weight22/04/2019 20:01:55
52 forum posts
14 photos

Good evening all,

Puzzling over the correct wiring of the coils into the circuit of the above design, an answer to the following query would be most helpful.

There are 4 wires from the two coils, which is the correct way to connect the wires to the supply, in series or parallel with each other.

This looks like a silly question to be asking but I cant make up my mind which would give me the most powerful result in operating the mechanism.

Thanks to any one able to help find the answer.

John Weight

Michael Gilligan22/04/2019 21:46:01
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12923 forum posts
555 photos

John,

I haven't studied Wilding's version, but Murday's patent shows the coils connected in series:

murday.jpg

.

MichaelG.

.

https://worldwide.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=189706212A&KC=A&FT=D&ND=3&date=18980309&DB=EPODOC&locale=en_EP

Edited By Michael Gilligan on 22/04/2019 21:46:43

duncan webster22/04/2019 22:51:17
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2014 forum posts
30 photos

Wiring in parallel gives more current for a given voltage and hence more oomph (to use the technical term). However you need to make sure either way that the coils are the right way round so the magnetic fields add up, not subtract. To check out a piece of steel across the poles and see how hard it is to pull it off. then swap one coil connections round, and see if it gets more or less. Alternatively you could use a compass, make sure the top end of one attracts the north end, and the top of the other attracts the south.

I'd start with them in series, if this doesn't give enough impulse switch to parallel

AdrianR23/04/2019 10:19:41
135 forum posts
3 photos

Looking at the drawings on page 6 and 7 it looks like a series connection to me. I would make some sense to have it series. It would halve the current the contacts have to break. In fig 1 it is showing a 6V battery, which should be enough for a series coils.

John Weight23/04/2019 20:11:15
52 forum posts
14 photos

Good evening all,

Many thanks for the replies re the clock wiring all of which were helpful in pointing me in the right direction. I have not yet had a chance to check things out in the workshop and probably won't be able to much before Friday, so, fingers crossed I shall be able to sort it out then.

Thanks again, John.

John Haine23/04/2019 22:02:28
2455 forum posts
132 photos

You will need a quench resistor across the coil to limit the inductive kick voltage when the contacts open and stop sparking which will erode them. A value of a few hundred ohms is typical. Modern practice would use a diode but that tends to cause a delay in the armature dropping out which may or may not be a problem.

Michael Gilligan01/05/2019 22:25:40
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12923 forum posts
555 photos

Just thought I should add this beauty, for reference: **LINK**

https://www.sellingantiques.co.uk/563155/murdays-patent-electromagnetic-clock/

MichaelG.

John Weight02/05/2019 19:36:48
52 forum posts
14 photos

Hello Micheal,

Thank you for your link re the Murday clock which I found most interesting, especially as I hadn't realised until I saw it that it had a transparent glass Dial, as in the one I made to John Wildings design I had incorporated a dial made from perspex. Thanks again for the link.

John

AdrianR03/05/2019 16:57:03
135 forum posts
3 photos

Another way to quench the arc is to use a capacitor from a car distributor.

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