On Saturday, 1 January 2022 at 21:37:39 UTC, Cydrome Leader wrote:
> Rich S <richsuli...@gmail.com> wrote: 
> > I watched the video but the design details 
> > are hard to determine. IF they wire an 
> > *incandescent lamp* in series with the 
> > output leg, then that would at least 
> > provide some current limiting.
> The terrible core will limit output current as well. It's a different 
> story on the primary side. I do wonder what the %Z is for that tranformer 
> shown in the first part of the video.
> > It wouldn't save someone from shock 
> > but might limit sparking and fire creation. 
> > That poor little diode, needs some protection 
> > against shorts. 
> > I saw the guy "sparking" by touching the 
> > battery clamps together while the unit 
> > was live. So shorting must have 
> > been expected....?
> It looks like they show the start of the making of one model, then switch 
> to the enclosure and completion of a different model. The frame clamps are 
> wood, then metal in the last half of the video. That must be for the 
> premium model.

I expect they use whatever they have. Why not.

> They do have fuses installed on the contraption. My guess 
> is they do nothing until half the windings are shorted in the first place. 

To be fair you don't want the fuse to pop every time the connectors touch

> The sparking was likely the final test procedure. 

and not a bad one. 

> I also wonder how this transformer stacks up against one from the US or 
> europe that was made in the mid to late 1800s.

identical I suspect.
If I were in their position, without the skills to make an smpsu or the money to buy decent parts, I'd do mostly the same. I'd see if there were cheaper alternatives to cotton.

On Friday, 31 December 2021 at 20:21:51 UTC, Rich S wrote:
> I watched the video but the design details 
> are hard to determine. IF they wire an 
> *incandescent lamp* in series with the 
> output leg, then that would at least 
> provide some current limiting. 
> It wouldn't save someone from shock 
> but might limit sparking and fire creation. 
> That poor little diode, needs some protection 
> against shorts. 
> I saw the guy "sparking" by touching the 
> battery clamps together while the unit 
> was live. So shorting must have 
> been expected....?

I doubt they'd go to the expense of a lightbulb.

On Friday, 31 December 2021 at 16:59:51 UTC, Cydrome Leader wrote:
> Ed Lee <edward....@gmail.com> wrote: 
> > On Thursday, December 30, 2021 at 5:32:09 PM UTC-8, Tabby wrote: 
> >> On Thursday, 30 December 2021 at 18:48:06 UTC, Cydrome Leader wrote: 
> >> > Tabby <tabb...@gmail.com> wrote: 
> >> > > On Saturday, 25 December 2021 at 02:59:09 UTC, jeff.li...@gmail.com wrote: 
> >> > >> On Fri, 24 Dec 2021 20:36:33 -0000 (UTC), Cydrome Leader 
> >> > >> <pres...@MUNGEpanix.com> wrote: 
> >> > >> 
> >> > >> >It looked like cloth covered wire for the transformer. I can't imagine 
> >> > >> >that's cheaper than varnish, but maybe there's another shop where they 
> >> > >> >twist it on by hand. 
> >> > >> In India: 
> >> > >> Cotton cloth costs Rs 65 ($0.85) per meter. 
> >> > >> <https://dir.indiamart.com/impcat/plain-cotton-fabric.html> 
> >> > > 
> >> > > 1m means something like 1x2m, though the width varies 
> >> > > 
> >> > >> Varnish costs about Rs 145 ($1.92) per kg. 
> >> > >> <https://dir.indiamart.com/search.mp?ss=varnish> 
> >> > >> 
> >> > >> I don't know the relative wire coverage area for cloth vs varnish, but 
> >> > >> they seem about equal. 
> >> > > 
> >> > > If we guess wildly at 10mm circumference for the cloth insulation: 
> >> > > 1x2m = 2sqm 
> >> > > 10mm x 1m = 
> >> > > So number of meters it covers = 2m/10mm = 200m 
> >> > > 
> >> > >> However, applying cloth insulation is a one 
> >> > >> step process, 
> >> > > 
> >> > > yes, one painfully slow process 
> >> > In the real world (so not the slums of pakistan) cloth insulation is woven 
> >> > on with a machine and not cut up from bedsheets or whatever else you folks 
> >> > are looking at. 
> >> heh. I assume folk were looking at cloth to estimate the cost of woven tube. 
> >> > >> while varnish requires thinning, dipping, drying, 
> >> > > 
> >> > > I assumed it would set/dry almost instantly, probably applied hot. I can't see much upside in using a formula that doesn't. 
> >> > > 
> >> > >> careful winding, testing for shorts, etc. 
> >> > > 
> >> > > I doubt they'd bother 
> >> > > 
> >> > >> Cloth seems easier. 
> >> > > 
> >> > > If I were in the 3rd world looking to go ultracheap I'd possibly pick 
> >> > > hot bitumenised paper. 
> >> > > 
> >> > > Those transformers look big but either 
> >> > > a) they're way ott for charging truck batteries 
> >> > > b) or they're for something else, probably stealing power 
> >> > they look about right to charge a truck battery, considering they're 
> >> > probably about 50% efficient. 
> >> They should be nearer to 100% than 50. A truck battery is what, 200Ah or so, or for an old Indian truck maybe 30Ah. Looking to cut costs always I doubt they'd charge it at more than 6A. They only need a short charge to get it started or a slow charge after rebuilding a battery. That's a huge transformer for 6A. 
> > 
> > It's absolutely overkill for starter battery charger. Perhaps they are building low voltage EV trucks?
> Why is it overkill? Nobody anywhere starts a truck with a 6amp battery 
> charger.

I guess 4A chargers are more common than 6, either works though.


> No matter the output of the first transformer in the video, the 
> only thing going for it is the huge thermal mass. You can probably charge 
> at least a couple batteries before it catches on fire and electrocutes 
> everybody crouched in the nearest puddle.

The one thing going for it is it's affordable.
They might be using high current diodes salvaged from SMPSUs.

Ed Lee <edward.ming.lee@gmail.com> wrote:
> On Saturday, January 1, 2022 at 1:37:39 PM UTC-8, Cydrome Leader wrote:
>> Rich S <richsuli...@gmail.com> wrote: 
>> > I watched the video but the design details 
>> > are hard to determine. IF they wire an 
>> > *incandescent lamp* in series with the 
>> > output leg, then that would at least 
>> > provide some current limiting.
>> The terrible core will limit output current as well. It's a different 
>> story on the primary side. I do wonder what the %Z is for that tranformer 
>> shown in the first part of the video.
>> > It wouldn't save someone from shock 
>> > but might limit sparking and fire creation. 
>> > That poor little diode, needs some protection 
>> > against shorts. 
>> > I saw the guy "sparking" by touching the 
>> > battery clamps together while the unit 
>> > was live. So shorting must have 
>> > been expected....?
>> It looks like they show the start of the making of one model, then switch 
>> to the enclosure and completion of a different model. The frame clamps are 
>> wood, then metal in the last half of the video. That must be for the 
>> premium model. They do have fuses installed on the contraption. My guess 
>> is they do nothing until half the windings are shorted in the first place. 
>> The sparking was likely the final test procedure. 
>> 
>> I also wonder how this transformer stacks up against one from the US or 
>> europe that was made in the mid to late 1800s.
> 
> I hope you mean 1900s.

No, I mean 1800s, back before AC became the standard and true mass 
production of transfomers probably took off.

On Saturday, January 1, 2022 at 1:37:39 PM UTC-8, Cydrome Leader wrote:
> Rich S <richsuli...@gmail.com> wrote: 
> > I watched the video but the design details 
> > are hard to determine. IF they wire an 
> > *incandescent lamp* in series with the 
> > output leg, then that would at least 
> > provide some current limiting.
> The terrible core will limit output current as well. It's a different 
> story on the primary side. I do wonder what the %Z is for that tranformer 
> shown in the first part of the video.
> > It wouldn't save someone from shock 
> > but might limit sparking and fire creation. 
> > That poor little diode, needs some protection 
> > against shorts. 
> > I saw the guy "sparking" by touching the 
> > battery clamps together while the unit 
> > was live. So shorting must have 
> > been expected....?
> It looks like they show the start of the making of one model, then switch 
> to the enclosure and completion of a different model. The frame clamps are 
> wood, then metal in the last half of the video. That must be for the 
> premium model. They do have fuses installed on the contraption. My guess 
> is they do nothing until half the windings are shorted in the first place. 
> The sparking was likely the final test procedure. 
> 
> I also wonder how this transformer stacks up against one from the US or 
> europe that was made in the mid to late 1800s.

I hope you mean 1900s.

Rich S <richsulinengineer@gmail.com> wrote:
> I watched the video but the design details
> are hard to determine. IF they wire an
> *incandescent lamp* in series with the
> output leg, then that would at least
> provide some current limiting.

The terrible core will limit output current as well. It's a different 
story on the primary side. I do wonder what the %Z is for that tranformer 
shown in the first part of the video.

> It wouldn't save someone from shock
> but might limit sparking and fire creation.
> That poor little diode, needs some protection
> against shorts. 
> I saw the guy "sparking" by touching the
> battery clamps together while the unit
> was live. So shorting must have
> been expected....?

It looks like they show the start of the making of one model, then switch 
to the enclosure and completion of a different model. The frame clamps are 
wood, then metal in the last half of the video. That must be for the 
premium model. They do have fuses installed on the contraption. My guess 
is they do nothing until half the windings are shorted in the first place. 
The sparking was likely the final test procedure.

I also wonder how this transformer stacks up against one from the US or 
europe that was made in the mid to late 1800s.

I watched the video but the design details
are hard to determine. IF they wire an
*incandescent lamp* in series with the
output leg, then that would at least
provide some current limiting.
It wouldn't save someone from shock
but might limit sparking and fire creation.
That poor little diode, needs some protection
against shorts. 
I saw the guy "sparking" by touching the
battery clamps together while the unit
was live. So shorting must have
been expected....?

Ed Lee <edward.ming.lee@gmail.com> wrote:
> On Thursday, December 30, 2021 at 5:32:09 PM UTC-8, Tabby wrote:
>> On Thursday, 30 December 2021 at 18:48:06 UTC, Cydrome Leader wrote: 
>> > Tabby <tabb...@gmail.com> wrote: 
>> > > On Saturday, 25 December 2021 at 02:59:09 UTC, jeff.li...@gmail.com wrote: 
>> > >> On Fri, 24 Dec 2021 20:36:33 -0000 (UTC), Cydrome Leader 
>> > >> <pres...@MUNGEpanix.com> wrote: 
>> > >> 
>> > >> >It looked like cloth covered wire for the transformer. I can't imagine 
>> > >> >that's cheaper than varnish, but maybe there's another shop where they 
>> > >> >twist it on by hand. 
>> > >> In India: 
>> > >> Cotton cloth costs Rs 65 ($0.85) per meter. 
>> > >> <https://dir.indiamart.com/impcat/plain-cotton-fabric.html> 
>> > > 
>> > > 1m means something like 1x2m, though the width varies 
>> > > 
>> > >> Varnish costs about Rs 145 ($1.92) per kg. 
>> > >> <https://dir.indiamart.com/search.mp?ss=varnish> 
>> > >> 
>> > >> I don't know the relative wire coverage area for cloth vs varnish, but 
>> > >> they seem about equal. 
>> > > 
>> > > If we guess wildly at 10mm circumference for the cloth insulation: 
>> > > 1x2m = 2sqm 
>> > > 10mm x 1m = 
>> > > So number of meters it covers = 2m/10mm = 200m 
>> > > 
>> > >> However, applying cloth insulation is a one 
>> > >> step process, 
>> > > 
>> > > yes, one painfully slow process 
>> > In the real world (so not the slums of pakistan) cloth insulation is woven 
>> > on with a machine and not cut up from bedsheets or whatever else you folks 
>> > are looking at.
>> heh. I assume folk were looking at cloth to estimate the cost of woven tube.
>> > >> while varnish requires thinning, dipping, drying, 
>> > > 
>> > > I assumed it would set/dry almost instantly, probably applied hot. I can't see much upside in using a formula that doesn't. 
>> > > 
>> > >> careful winding, testing for shorts, etc. 
>> > > 
>> > > I doubt they'd bother 
>> > > 
>> > >> Cloth seems easier. 
>> > > 
>> > > If I were in the 3rd world looking to go ultracheap I'd possibly pick 
>> > > hot bitumenised paper. 
>> > > 
>> > > Those transformers look big but either 
>> > > a) they're way ott for charging truck batteries 
>> > > b) or they're for something else, probably stealing power 
>> > they look about right to charge a truck battery, considering they're 
>> > probably about 50% efficient.
>> They should be nearer to 100% than 50. A truck battery is what, 200Ah or so, or for an old Indian truck maybe 30Ah. Looking to cut costs always I doubt they'd charge it at more than 6A. They only need a short charge to get it started or a slow charge after rebuilding a battery. That's a huge transformer for 6A.
> 
> It's absolutely overkill for starter battery charger.  Perhaps they are building low voltage EV trucks?

Why is it overkill? Nobody anywhere starts a truck with a 6amp battery 
charger. No matter the output of the first transformer in the video, the 
only thing going for it is the huge thermal mass. You can probably charge 
at least a couple batteries before it catches on fire and electrocutes 
everybody crouched in the nearest puddle.

On Thursday, December 30, 2021 at 5:32:09 PM UTC-8, Tabby wrote:
> On Thursday, 30 December 2021 at 18:48:06 UTC, Cydrome Leader wrote: 
> > Tabby <tabb...@gmail.com> wrote: 
> > > On Saturday, 25 December 2021 at 02:59:09 UTC, jeff.li...@gmail.com wrote: 
> > >> On Fri, 24 Dec 2021 20:36:33 -0000 (UTC), Cydrome Leader 
> > >> <pres...@MUNGEpanix.com> wrote: 
> > >> 
> > >> >It looked like cloth covered wire for the transformer. I can't imagine 
> > >> >that's cheaper than varnish, but maybe there's another shop where they 
> > >> >twist it on by hand. 
> > >> In India: 
> > >> Cotton cloth costs Rs 65 ($0.85) per meter. 
> > >> <https://dir.indiamart.com/impcat/plain-cotton-fabric.html> 
> > > 
> > > 1m means something like 1x2m, though the width varies 
> > > 
> > >> Varnish costs about Rs 145 ($1.92) per kg. 
> > >> <https://dir.indiamart.com/search.mp?ss=varnish> 
> > >> 
> > >> I don't know the relative wire coverage area for cloth vs varnish, but 
> > >> they seem about equal. 
> > > 
> > > If we guess wildly at 10mm circumference for the cloth insulation: 
> > > 1x2m = 2sqm 
> > > 10mm x 1m = 
> > > So number of meters it covers = 2m/10mm = 200m 
> > > 
> > >> However, applying cloth insulation is a one 
> > >> step process, 
> > > 
> > > yes, one painfully slow process 
> > In the real world (so not the slums of pakistan) cloth insulation is woven 
> > on with a machine and not cut up from bedsheets or whatever else you folks 
> > are looking at.
> heh. I assume folk were looking at cloth to estimate the cost of woven tube.
> > >> while varnish requires thinning, dipping, drying, 
> > > 
> > > I assumed it would set/dry almost instantly, probably applied hot. I can't see much upside in using a formula that doesn't. 
> > > 
> > >> careful winding, testing for shorts, etc. 
> > > 
> > > I doubt they'd bother 
> > > 
> > >> Cloth seems easier. 
> > > 
> > > If I were in the 3rd world looking to go ultracheap I'd possibly pick 
> > > hot bitumenised paper. 
> > > 
> > > Those transformers look big but either 
> > > a) they're way ott for charging truck batteries 
> > > b) or they're for something else, probably stealing power 
> > they look about right to charge a truck battery, considering they're 
> > probably about 50% efficient.
> They should be nearer to 100% than 50. A truck battery is what, 200Ah or so, or for an old Indian truck maybe 30Ah. Looking to cut costs always I doubt they'd charge it at more than 6A. They only need a short charge to get it started or a slow charge after rebuilding a battery. That's a huge transformer for 6A.

It's absolutely overkill for starter battery charger.  Perhaps they are building low voltage EV trucks?

On Thursday, 30 December 2021 at 18:48:06 UTC, Cydrome Leader wrote:
> Tabby <tabb...@gmail.com> wrote: 
> > On Saturday, 25 December 2021 at 02:59:09 UTC, jeff.li...@gmail.com wrote: 
> >> On Fri, 24 Dec 2021 20:36:33 -0000 (UTC), Cydrome Leader 
> >> <pres...@MUNGEpanix.com> wrote: 
> >> 
> >> >It looked like cloth covered wire for the transformer. I can't imagine 
> >> >that's cheaper than varnish, but maybe there's another shop where they 
> >> >twist it on by hand. 
> >> In India: 
> >> Cotton cloth costs Rs 65 ($0.85) per meter. 
> >> <https://dir.indiamart.com/impcat/plain-cotton-fabric.html> 
> > 
> > 1m means something like 1x2m, though the width varies 
> > 
> >> Varnish costs about Rs 145 ($1.92) per kg. 
> >> <https://dir.indiamart.com/search.mp?ss=varnish> 
> >> 
> >> I don't know the relative wire coverage area for cloth vs varnish, but 
> >> they seem about equal. 
> > 
> > If we guess wildly at 10mm circumference for the cloth insulation: 
> > 1x2m = 2sqm 
> > 10mm x 1m = 
> > So number of meters it covers = 2m/10mm = 200m 
> > 
> >> However, applying cloth insulation is a one 
> >> step process, 
> > 
> > yes, one painfully slow process
> In the real world (so not the slums of pakistan) cloth insulation is woven 
> on with a machine and not cut up from bedsheets or whatever else you folks 
> are looking at.

heh. I assume folk were looking at cloth to estimate the cost of woven tube.

> >> while varnish requires thinning, dipping, drying, 
> > 
> > I assumed it would set/dry almost instantly, probably applied hot. I can't see much upside in using a formula that doesn't. 
> > 
> >> careful winding, testing for shorts, etc. 
> > 
> > I doubt they'd bother 
> > 
> >> Cloth seems easier. 
> > 
> > If I were in the 3rd world looking to go ultracheap I'd possibly pick 
> > hot bitumenised paper. 
> > 
> > Those transformers look big but either 
> > a) they're way ott for charging truck batteries 
> > b) or they're for something else, probably stealing power
> they look about right to charge a truck battery, considering they're 
> probably about 50% efficient.

They should be nearer to 100% than 50. A truck battery is what, 200Ah or so, or for an old Indian truck maybe 30Ah. Looking to cut costs always I doubt they'd charge it at more than 6A. They only need a short charge to get it started or a slow charge after rebuilding a battery. That's a huge transformer for 6A.