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  • J Tiers
    replied
    Originally posted by The Artful Bodger View Post
    The adjustment steps are (presumably) taps on the transformer secondary and the principle would be exactly the same for half or full wave rectification.

    Considerations of core saturation et al aside the choice of half wave is likely due to some old wives' tale that the 'rough' DC is better for battery charging.

    Ten coarse steps of coarse voltage adjustment plus ten steps of fine would give a total of 100 voltage steps!
    yes, the principle is the same.

    But, if you use two diodes (the minimum for full wave) you need a center tapped winding, and the "steps" become more complicated. If you use a full wave bridge, then the same single plug system works, but you have to use, and mount, connect, etc, 4 diodes.

    The largest package full wave bridges are about 35A Their meter seems to go to 10 A. They are using a large stud mount diode, probably because they want something that will stand the inevitable short circuiting by folks who are not any too clear on dealing with electricity. The "test" does not pop the fuse, although it "pegs" the meter with a bang, so................. presumably it is large enough to not be particularly effective at protecting a rectifier. They just want to have a product that is fairly fool-proof for use out in the sticks; cheap, and not prone to popping fuses often.

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  • The Artful Bodger
    replied
    The adjustment steps are (presumably) taps on the transformer secondary and the principle would be exactly the same for half or full wave rectification.

    Considerations of core saturation et al aside the choice of half wave is likely due to some old wives' tale that the 'rough' DC is better for battery charging.

    Ten coarse steps of coarse voltage adjustment plus ten steps of fine would give a total of 100 voltage steps!

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  • J Tiers
    replied
    I'd bet the two sets of plug connections are to adjust the voltage in finer steps.

    The half wave messes up the transformer, but is as cheap as it gets, using one plug for adjustment. That used to be done back when tubes were used for rectification, and it worked "ok". If they used a two diode full wave, they would need a different adjustment method. A full wave bridge would be extra expense.

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  • The Artful Bodger
    replied
    I must admit I have not seen cotton covered wire in recent years, not even in some of the junk I get to dismantle. The machine that applies the cotton is probably a hundred years old and of course the cotton may be locally produced and the windings are varnish(?) dunked so not too bad by old time standards.

    They do close the core after all the windings are in place.

    The half wave system seems odd as a diode bridge cannot be that expensive. Likewise, why do some units have three windings?

    The plug leads adjust the output voltage? Why are there two? Is one of those windings used as a choke to reduce current?

    Rusty steel in the core laminations and of course rust is a poor conductor so maybe that will reduce eddy current losses!

    Yea, ancient transformer construction and quite a few shortcuts in the construction but I could be lead to believe the circuit design is actually smarter than it at first appears.

    The cabinets have a nice choice of colours and some appear to be designed to stand straight on a dirt floor!

    All in all, I would like to have a nice hulking battery charger for the range of batteries we have at the aviation museum and I am sure that these ones will not spit the dummy if connect to a 'too flat' battery. I wonder how much they cost but the freight to NZ would be the killer.





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  • J Tiers
    replied
    I don't think the wrap their own wire... the orange stuff was regular plastic insulated wire. The coil wire may be varnish insulated and then with a top wrap to make it less easy to damage in handling and winding. "Magnet wire" used to be available like that here in the US.

    The sleeving for protection is pretty normal, even a higher quality feature. What the cores are made of is a question... "Random steel" varies in it's magnetic characteristics. But that is apparently secondary to their main goal of making transformers for their product. And we have no clue what ANY of these factories are using as far as composition of steel. Scrap can be anything from CRS to transformer steel, to some form of tool steel or specialized alloy. It all "looks" the same.

    My suspicion is that they have some clue what they have. The various casting operations seem to select their melt material in various proportions from piles. I'd bet they bought the scrap with a good idea of what it was. Pakistan has some good engineers, and the rest of the population are not 100% rubes.

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  • A.K. Boomer
    replied
    Agree'd their just doing the best with what they have,,, but wow what it takes to wrap all that wire in some kinda sheathing, and you know their not "hammering out" their own copper wire at that "factory"

    Just an observation as to why they can't get varnish insulated wire to begin with... nothing to do with dipping it themselves --- just buying it in bulk like everyone else - their already buying the copper that way...

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  • J Tiers
    replied
    There were two white parts. The first was the basic wire insulation, and the second was a protective sleeve for the leads where they come out.

    Old time transformers which that resembles, had cloth, or threads wound around the wire. That wire may be like that. It is effective, and absorbs varnish, becming good insulation.

    Yes, varnish insulation is more space efficient. And, real varnishing is done by vacuum; dunk, pull a vacuum, let the air bubble out, then let the pressure back in to force the varnish into all the spaces. For that, the varnish is usually a heat-cured varnish that does not rely on a solvent evaporating. it's more like bakelite.

    It's pretty obvious that neither space, nor efficiency is very important to them. Cheap chargers for low-profit shops. Like cheap wrenches for the same shops. It gets people working, and money moving, which is the basis of an economy.

    You can't really fault it, although the wages are likely to be very low except for the most expert workers.

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  • A.K. Boomer
    replied
    Originally posted by J Tiers View Post


    As for the varnish, you must have missed the part where the kid carried the windings up to the "loft" and dunked them in the varnish tank.
    Im listening because you know electrical stuff far better than me --- see how that works???

    anyways --- what was the white sheathing on the transformer wires being wound BEFORE dunking the whole glob into the varnish - which i did not miss,,,

    that's what I was talking about - that's thick stuff and all adds up to more space/less efficiency,

    All the transformer wires iv seen are VARNISHED FIRST and then just wrapped that way like motor windings or anything else... it protects them from touching each other - some are "double dunked" meaning the word we so frequently have seen advertised as "double insulated" ...

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  • J Tiers
    replied
    Originally posted by A.K. Boomer View Post
    Now I know your just stirring the pot JT, thing would be half the size if they discovered "varnish insulation" for the transformer wiring,,, and nice "operator switchboard" effect,,, yeah those external wires are going to be lifetime for sure...

    but only due to the fact that they provided some "kindling" with it to be able to keep warm in the colder months.... so one season otta due...

    capped it all off with a dead short test at the end, not to do anything with testing the amp meters accuracy --- nope - just that it's "magically connected" then call it good... hopefully shipped without the POS still being on fire and burning down the truck with the "melded crank" or putting more demands on the "soft wrench" stowed away under the goat excrement - due to one of the tires popping from the heat and needing a quick change with the revamped roman chariot wheel....
    Not stirring the pot.

    I actually was impressed with the effort put into making the thing. They do pretty much all that they reasonably could, except the case.

    NOT impressed with the design...... although some of it may be explained by the half-wave rectifier that it appears they use..... DC on the transformer windings is generally considered bad, and it makes the powerco unhappy as well. But that transformer may be less affected by it than some.... it does not seem very efficient, but that may also make it less likely to saturate with DC. And it also may help make a constant current for charging. Whether that is by accident or design, I could not be telling you.

    There does seem to be a part of the core laminations missing on one side at the top, which could have an effect like that. Might be just camera angle, though.

    As for the varnish, you must have missed the part where the kid carried the windings up to the "loft" and dunked them in the varnish tank.

    The "kindling"...... at least some of them seem to have angle iron clamps.... the one at the end, that had just one meter, not the two meters the others had, was using angle iron.
    Last edited by J Tiers; 01-08-2022, 11:27 PM.

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  • A.K. Boomer
    replied
    Now I know your just stirring the pot JT, thing would be half the size if they discovered "varnish insulation" for the transformer wiring,,, and nice "operator switchboard" effect,,, yeah those external wires are going to be lifetime for sure...

    but only due to the fact that they provided some "kindling" with it to be able to keep warm in the colder months.... so one season otta due...

    capped it all off with a dead short test at the end, not to do anything with testing the amp meters accuracy --- nope - just that it's "magically connected" then call it good... hopefully shipped without the POS still being on fire and burning down the truck with the "melded crank" or putting more demands on the "soft wrench" stowed away under the goat excrement - due to one of the tires popping from the heat and needing a quick change with the revamped roman chariot wheel....

    Leave a comment:


  • J Tiers
    replied
    This just has to be seen.... if you are familiar with electrical or electronics you will appreciate it for sure.......

    https://www.youtube.com/watch?v=cpaWCedoptA

    A real case of when yah gotta, yah gotta.

    Leave a comment:


  • vectorwarbirds
    replied
    Originally posted by Rustybolt View Post

    Oddly enough the rest of the world that isn't us has a need for this kind of thing. Kinda like the tool kit on your motorcycle. It's crap until you find yourself broke down by the side of some rural road.


    Interesting you should mention that. I have a friend that spent 18 months in India with a portion of that time riding a diesel powered Royal Enfield motorcycle to Nepal. I sent him this video and he told me he saw those L wrenches with sockets sets all over the place. Told me they could take apart an entire motorcycle and put it back together with them and he never saw one bend or broken. So apparently they work fine for their proposed purpose by people smart enough to use them correctly.

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  • Rustybolt
    replied
    Originally posted by plunger View Post
    Love the guy with the pink gloves. Sad to see children do this. The dude tightening the chuck on the broach operation must have a strong back. the machine is at the perfect heightto force him to buckle over all day long. How do they even find a market for this soft crap.
    Oddly enough the rest of the world that isn't us has a need for this kind of thing. Kinda like the tool kit on your motorcycle. It's crap until you find yourself broke down by the side of some rural road.

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  • JRouche
    replied
    I have a problem with this Post. "More quality tools from our hard working friends in Pakistan!
    "

    It is offensive to me . Why? You mistakenly used the incorrect tearms, termonolgy. Not your fault.

    I dont like to see or hear of any person hurting another. It is just my nature, I cant help it. JR JR

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  • JRouche
    replied
    Originally posted by A.K. Boomer View Post
    those wrench/bars in the OP vid ..
    Hahaaa! This part of the conversation is my fault. I did not see the video and really just dont watch yertube vid.

    My bust again. JR

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