On Tuesday, 30 June 2020 14:14:53 UTC+1, amdx wrote:
> Also, I'll put a switch on the primary, but I can't guarantee that
> switch will always get turned off after the power switch on the leaf
> blower is shut off. My wife will be the user, I can put a light in the
> circuit, she would be certain to turn off an unneeded light.
>
>
> Mikek
Now there's optimism. If it can be misused, it will be.
NT
Reply by Cydrome Leader●August 19, 20202020-08-19
Bill Martin <wwm@wwmartin.net> wrote:
> On 7/1/20 11:03 PM, Cydrome Leader wrote:
>> Chris Jones <lugnut808@spam.yahoo.com> wrote:
>>> On 30/06/2020 00:46, Michael Terrell wrote:
>>>> Ceramic transmitting tubes and semiconductors also use BeO. Those warning labels don't always follow equipment through production and testing. A test tech on the GRC106 ended up in the hospital when one of the Eimac finals was damaged during shipping from Mexico to Cincinnati. They were just tossing the paperwork since they couldn't read English. Luckily for that tech, the man at the next bench saw him with the damaged tube. He wrapped a plastic bag over the tech's hands and the tube. He had someone call for an a.mbulsnce as he hurried him running to a sink to wet down the dust. He saved his coworker's life. After that, the paperwork was wired to each subassembly that contained BeO. YOLO.
>>>>
>>>
>>> I can believe that BeO must be pretty nasty because they used to give
>>> warnings about it, even back in the time when warnings were reserved for
>>> actually very dangerous things. Nowadays due to every harmless thing
>>> being plastered with warnings, they have become rather devalued and it
>>> is much harder to identify what really is dangerous.
>>
>> yup. Starbuck Coffee in CA post the prop 65 warnings about dangerous
>> chemicals (yes, coffee) in their stores. They have lots of free time in CA
>> it seems.
>>
> Hmm, what kind of warning would CA put on a magnetron coupled to a
> waveguide full of pressurized SF6? :-) That was pumping 5MW pulses to a
> big dish...
The warning would probably have to be in spanish and not offend retards
that can't decide between the men and women's restrooms.
Reply by Bill Martin●July 6, 20202020-07-06
On 7/1/20 11:03 PM, Cydrome Leader wrote:
> Chris Jones <lugnut808@spam.yahoo.com> wrote:
>> On 30/06/2020 00:46, Michael Terrell wrote:
>>> Ceramic transmitting tubes and semiconductors also use BeO. Those warning labels don't always follow equipment through production and testing. A test tech on the GRC106 ended up in the hospital when one of the Eimac finals was damaged during shipping from Mexico to Cincinnati. They were just tossing the paperwork since they couldn't read English. Luckily for that tech, the man at the next bench saw him with the damaged tube. He wrapped a plastic bag over the tech's hands and the tube. He had someone call for an a.mbulsnce as he hurried him running to a sink to wet down the dust. He saved his coworker's life. After that, the paperwork was wired to each subassembly that contained BeO. YOLO.
>>>
>>
>> I can believe that BeO must be pretty nasty because they used to give
>> warnings about it, even back in the time when warnings were reserved for
>> actually very dangerous things. Nowadays due to every harmless thing
>> being plastered with warnings, they have become rather devalued and it
>> is much harder to identify what really is dangerous.
>
> yup. Starbuck Coffee in CA post the prop 65 warnings about dangerous
> chemicals (yes, coffee) in their stores. They have lots of free time in CA
> it seems.
>
Hmm, what kind of warning would CA put on a magnetron coupled to a
waveguide full of pressurized SF6? :-) That was pumping 5MW pulses to a
big dish...
> Phil Allison <pallison49@gmail.com> wrote:
> > Cydrome Leader wrote:
> >
> > =====================
> > >
> >> > ** Saturation can be avoided by running the MOT from a triac dimmer.
> >> >
> >> > Thousands of Carver "Magnetic Field" amplifiers attest that fact.
> >>
> >> Can you explain what the whole carver magic power supply is?
> >>
> >
> > ** No magic, Bob just borrowed an idea from some DC PSU designs where
> > rather than having multiple regulator devices and huge heat sinks after
> > a transformer based supply - you put a hefty *phase controlled* triac in
> > the AC feed to a transformer to * pre-regulate the average DC output.
> > Then you can use small heat sinks and drop maybe 1.5 volts at most.
> >
> > Bob did not need pure DC for his amp design or full output for long
> > periods - just enough DC for domestic audio use. So he just used the
> > unregulated DC voltage to control the firing angle of the triac and left
> > it at that. This meant he could make the power tranny *much* smaller
> > than usual and far cheaper.
> >
> > The transformers were engineered to operate normally at 70% of the AC
> > supply so the triac chopped the AC wave to get this peak value -
> > increasing the firing angle when needed to make up losses under load.
> >
> > The amps used 8 x DC rails, typically +/- 25, 50, 80 & 120 volts with 8
> > output transistors all in series. This allowed the heat developed by a
> > class B stage to be much reduced so needing way less heat sinking. The
> > aluminium case became the only heat sink.
> >
> > The result as the "Carver Cube" - tiny and light weight though packing a
> > 200 wpc punch for short periods until the tranny started to cook.
>
> Ok, so trying to make sense of this. It's basically a SCR/Triac
> preregulated power supply like Sorenson or a HP bench supply, but with a
> transformer that's undersized and would burn up at full line voltage?
>
** Basically - yes.
> > My testing showed full sine wave power on both channel at 8 ohms was
> > available to 2 or 3 minutes at most - and 90 seconds with 4 ohm loads.
> >
> > Then the resin inside the tranny started to emit smoke - I kid you not.
>
> Sounds like a lot of effort to make a transformer smaller than it should
> be.
>
> On Wed, 1 Jul 2020 18:34:30 -0500, amdx <amdx@knology.net> wrote:
>
>>Tomorrow, I will weld the core
>>sections together.
>
> I believe I read somewhere that you should not do that. With an
> ordinary welder, you will be putting enough heat into the core to risk
> damage to the insulation between the layers of steel in the core. The
> factory welding technique is extremely fast, so that much less heat is
> required.
>
> Firmly clamping them together was the recommendation.
It's supposed to be a plasma welder, so like a plasma cutter with less
gas flow, somehow.
The oxide coating should be pretty tough- it's applied with heat in the
first place.
Reply by Cydrome Leader●July 3, 20202020-07-03
amdx <amdx@knology.net> wrote:
> On 7/2/2020 12:57 AM, Cydrome Leader wrote:
>> amdx <amdx@knology.net> wrote:
>>> On 7/1/2020 12:13 PM, dagmargoodboat@yahoo.com wrote:
>>>> On Tuesday, June 30, 2020 at 9:14:53 AM UTC-4, amdx wrote:
>>>>> On 6/29/2020 8:33 AM, amdx wrote:
>>>>>> On 6/28/2020 8:55 PM, Phil Allison wrote:
>>>>>>> Robert Roland wrote:
>>>>>>>
>>>>>>> ====================
>>>>>>>
>>>>>>>>
>>>>>>>> An unloaded transformer is almost entirely inductive, so the PF will
>>>>>>>> be very low. As the load increases, the PF will also increase. This is
>>>>>>>> normal. All transformer are like that.
>>>>>>>>
>>>>>>> ** If the same tranny is undergoing core saturation, the current wave
>>>>>>> is highly distorted and maxima tend to co-incide with zero crossings -
>>>>>>> exacerbating the poor PF.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> One thing to look out for with MOTs, is that they are run very "hard",
>>>>>>>> i.e. they magnetize the core well into saturation. That way, the
>>>>>>>> manufacturers can save on iron, which saves on weight, which saves on
>>>>>>>> cost. Since the MOT is normally run at fairly low duty cycle, and with
>>>>>>>> fan cooling, they can get away with that. You may find that the
>>>>>>>> transformer with zero load will draw 100 W or more of real power. If
>>>>>>>> you leave it running for some amount of time, it will get very hot.
>>>>>>>> The remedy for this is to add some additional turns to the primary
>>>>>>>> winding. This will, of course, require you to add some additional
>>>>>>>> secondary turns to reach the output voltage you want.
>>>>>>>>
>>>>>>>> Intuitively, you might think that adding more primary turns would
>>>>>>>> increase the magnetization, therefore worsen the saturation situation.
>>>>>>>> The reason it does not, is that the added windings increase the
>>>>>>>> inductance of the primary winding, which results in a reduction in
>>>>>>>> magnetizing current. The current reduces relatively more than the
>>>>>>>> increase in turns.
>>>>>>>>
>>>>>>> ** Magnetisation goes up and down with the number of primary turns and
>>>>>>> applied voltage while inductance follows the square of the number of
>>>>>>> turns.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> .....?? Phil
>>>>>>>
>>>>>>
>>>>>> ??I have graphed the Voltage and Current of the original primary winding
>>>>>> and after adding 37 Turns, 48 Turns and 60 Turns.
>>>>>> Any comments?
>>>>>>> https://www.dropbox.com/s/0n1y4yh5o0j2sg6/mot%20primary%20voltage%20vs%20current%202%20graphs.jpg?dl=0
>>>>>>>
>>>>>>
>>>>>> ?????????????????????????????????????????????????????????????????????????????????????????????????????? Mikek
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> I haven't got any response to the graphs, so without that, I'm going
>>>>> to go with adding 60 primary turns, adjust the secondary to get the proper
>>>>> secondary voltage and see if it delivers the required voltage at 8 amps.
>>>>
>>>> Great graphs.
>>>>
>>>> The first graph showed the virgin transformer was saturating (losing
>>>> inductance) at 90 volts, where the current eyeballs-out to be about
>>>> 20% higher than the straight-line slope beforehand.
>>>>
>>>> To my eyeball, aided with a ruler, the 62-extra-turns version hits
>>>> that same 20% inductance loss / 20% "extra" current at about 115VAC.
>>>> That looks reasonable to me.
>>>
>>>
>>> Thanks for the input, Maybe I should have added a few more turns my
>>> voltage runs about 122Vac. It's to late now, I have dipped and baked the
>>> coils in an electric motor varnish, assembled it and then after assembly
>>> dipped and baked the whole thing. Tomorrow, I will weld the core
>>> sections together.
>>> For those that don't know, MOTs are are one stacked E section and one
>>> stacked I section that are welded along each outside edge. I just cut
>>> the welds with a hack saw so I could install my coils.
>>>
>>> Mikek
>>>
>>
>> I'd be interested to see photos of the finished transformer. The last one
>> I messed with took way longer to cut the secondary winding out of than I
>> expected. Was using a hacksaw and chisel and hammer. It wasn't as easy as
>> it looks like in motor rewinding videos on youtube.
>>
>
> It's not pretty, it's well insulated, coils have been triple dipped in
> varish and baked, the whole transformer dipped once. I don't hear any
> vibration, so it looks good so far.
> Here are the pics, FWIW.
>> https://www.dropbox.com/s/xnri429xz6an0qb/mot%203%20coils.jpg?dl=0
>
>> https://www.dropbox.com/s/sy86tuzhml2jodp/mot%20sec%20side.jpg?dl=0
>
>> https://www.dropbox.com/s/vqkg4e8hp6xrzg3/mot%20pri%20side.jpg?dl=0
>
> Mikek
Looks good.
Reply by Cydrome Leader●July 3, 20202020-07-03
Phil Allison <pallison49@gmail.com> wrote:
> Cydrome Leader wrote:
>
> =====================
> >
>> > ** Saturation can be avoided by running the MOT from a triac dimmer.
>> >
>> > Thousands of Carver "Magnetic Field" amplifiers attest that fact.
>>
>> Can you explain what the whole carver magic power supply is?
>>
>
> ** No magic, Bob just borrowed an idea from some DC PSU designs where
> rather than having multiple regulator devices and huge heat sinks after
> a transformer based supply - you put a hefty *phase controlled* triac in
> the AC feed to a transformer to * pre-regulate the average DC output.
> Then you can use small heat sinks and drop maybe 1.5 volts at most.
>
> Bob did not need pure DC for his amp design or full output for long
> periods - just enough DC for domestic audio use. So he just used the
> unregulated DC voltage to control the firing angle of the triac and left
> it at that. This meant he could make the power tranny *much* smaller
> than usual and far cheaper.
>
> The transformers were engineered to operate normally at 70% of the AC
> supply so the triac chopped the AC wave to get this peak value -
> increasing the firing angle when needed to make up losses under load.
>
> The amps used 8 x DC rails, typically +/- 25, 50, 80 & 120 volts with 8
> output transistors all in series. This allowed the heat developed by a
> class B stage to be much reduced so needing way less heat sinking. The
> aluminium case became the only heat sink.
>
> The result as the "Carver Cube" - tiny and light weight though packing a
> 200 wpc punch for short periods until the tranny started to cook.
Ok, so trying to make sense of this. It's basically a SCR/Triac
preregulated power supply like Sorenson or a HP bench supply, but with a
transformer that's undersized and would burn up at full line voltage?
> My testing showed full sine wave power on both channel at 8 ohms was
> available to 2 or 3 minutes at most - and 90 seconds with 4 ohm loads.
>
> Then the resin inside the tranny started to emit smoke - I kid you not.
Sounds like a lot of effort to make a transformer smaller than it should
be.
Here's what I have the Carver AV-705
https://hometheaterhifi.com/volume_4_2/av705.html
The description mentions "magnified current amplification" and "This
allows the output section to deliver high voltage when necessary, or high
current. The older designs used "Magnetic Field" technology, which allowed
only high voltage. Both designs are class H, in that the rail voltage is
variable, making the amplifier very efficient and cool-running. "
Maybe there's a TRAIC light dimmer in there too? I once had a service
guide for it, but that vanished as well as the copy I bought years later.
I don't recall them going past block diagrams though. Considering there 5
identical amplifier modules, it seems like less a direct lighting strike,
you'd be able to fix any problem it has by checking any of 4 other
identical parts.
Reply by amdx●July 2, 20202020-07-02
On 7/2/2020 9:28 AM, amdx wrote:
> On 7/2/2020 12:57 AM, Cydrome Leader wrote:
>> amdx <amdx@knology.net> wrote:
>>> On 7/1/2020 12:13 PM, dagmargoodboat@yahoo.com wrote:
>>>> On Tuesday, June 30, 2020 at 9:14:53 AM UTC-4, amdx wrote:
>>>>> On 6/29/2020 8:33 AM, amdx wrote:
>>>>>> On 6/28/2020 8:55 PM, Phil Allison wrote:
>>>>>>> Robert Roland wrote:
>>>>>>>
>>>>>>> ====================
>>>>>>>
>>>>>>>>
>>>>>>>> An unloaded transformer is almost entirely inductive, so the PF
>>>>>>>> will
>>>>>>>> be very low. As the load increases, the PF will also increase.
>>>>>>>> This is
>>>>>>>> normal. All transformer are like that.
>>>>>>>>
>>>>>>> ** If the same tranny is undergoing core saturation, the current
>>>>>>> wave
>>>>>>> is highly distorted and maxima tend to co-incide with zero
>>>>>>> crossings -
>>>>>>> exacerbating the poor PF.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> One thing to look out for with MOTs, is that they are run very
>>>>>>>> "hard",
>>>>>>>> i.e. they magnetize the core well into saturation. That way, the
>>>>>>>> manufacturers can save on iron, which saves on weight, which
>>>>>>>> saves on
>>>>>>>> cost. Since the MOT is normally run at fairly low duty cycle,
>>>>>>>> and with
>>>>>>>> fan cooling, they can get away with that. You may find that the
>>>>>>>> transformer with zero load will draw 100 W or more of real
>>>>>>>> power. If
>>>>>>>> you leave it running for some amount of time, it will get very hot.
>>>>>>>> The remedy for this is to add some additional turns to the primary
>>>>>>>> winding. This will, of course, require you to add some additional
>>>>>>>> secondary turns to reach the output voltage you want.
>>>>>>>>
>>>>>>>> Intuitively, you might think that adding more primary turns would
>>>>>>>> increase the magnetization, therefore worsen the saturation
>>>>>>>> situation.
>>>>>>>> The reason it does not, is that the added windings increase the
>>>>>>>> inductance of the primary winding, which results in a reduction in
>>>>>>>> magnetizing current. The current reduces relatively more than the
>>>>>>>> increase in turns.
>>>>>>>>
>>>>>>> ** Magnetisation goes up and down with the number of primary
>>>>>>> turns and
>>>>>>> applied voltage while inductance follows the square of the number of
>>>>>>> turns.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> .....?? Phil
>>>>>>>
>>>>>>
>>>>>> ??I have graphed the Voltage and Current of the original
>>>>>> primary winding
>>>>>> and after adding 37 Turns, 48 Turns and 60 Turns.
>>>>>> Any comments?
>>>>>>> https://www.dropbox.com/s/0n1y4yh5o0j2sg6/mot%20primary%20voltage%20vs%20current%202%20graphs.jpg?dl=0
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> ??????????????????????????????????????????????????????????????????????????????????????????????????????
>>>>>> Mikek
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> I haven't got any response to the graphs, so without that, I'm
>>>>> going
>>>>> to go with adding 60 primary turns, adjust the secondary to get the
>>>>> proper
>>>>> secondary voltage and see if it delivers the required voltage at 8
>>>>> amps.
>>>>
>>>> Great graphs.
>>>>
>>>> The first graph showed the virgin transformer was saturating (losing
>>>> inductance) at 90 volts, where the current eyeballs-out to be about
>>>> 20% higher than the straight-line slope beforehand.
>>>>
>>>> To my eyeball, aided with a ruler, the 62-extra-turns version hits
>>>> that same 20% inductance loss / 20% "extra" current at about 115VAC.
>>>> That looks reasonable to me.
>>>
>>>
>>> Thanks for the input, Maybe I should have added a few more turns my
>>> voltage runs about 122Vac. It's to late now, I have dipped and baked the
>>> coils in an electric motor varnish, assembled it and then after assembly
>>> dipped and baked the whole thing. Tomorrow, I will weld the core
>>> sections together.
>>> For those that don't know, MOTs are are one stacked E section and one
>>> stacked I section that are welded along each outside edge. I just cut
>>> the welds with a hack saw so I could install my coils.
>>>
>>> Mikek
>>>
>>
>> I'd be interested to see photos of the finished transformer. The last one
>> I messed with took way longer to cut the secondary winding out of than I
>> expected. Was using a hacksaw and chisel and hammer. It wasn't as easy as
>> it looks like in motor rewinding videos on youtube.
>>
>
> It's not pretty, it's well insulated, coils have been triple dipped in
> varish and baked, the whole transformer dipped once. I don't hear any
> vibration, so it looks good so far.
> Here are the pics, FWIW.
>> https://www.dropbox.com/s/xnri429xz6an0qb/mot%203%20coils.jpg?dl=0
>
>> https://www.dropbox.com/s/sy86tuzhml2jodp/mot%20sec%20side.jpg?dl=0
>
>> https://www.dropbox.com/s/vqkg4e8hp6xrzg3/mot%20pri%20side.jpg?dl=0
>
> Mikek
>
>
I have the secondary loaded with 8.5 amps. Readings from my
Kill-a-watt are as follows. 120.8V, PF-0.97, Va-233, W-226, A-1.92 amps.
FWIW, my Bryman BM235 Multimeter reads 122.4Vac on the primary.
I'm measuring coil temperatures with a thermocouple, after 1 hr the
secondary measures 217*F Original Primary *123F and the added 60 turn
primary (smaller Diameter wire) is 186*F. It's next to the secondary and
heated through two sheets of insulation.
I will add a fan. It wasn't very hot at 10 minutes, duty cycle would
be about 10 minutes on 24 hrs off.
Mikek
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Reply by amdx●July 2, 20202020-07-02
On 7/2/2020 12:57 AM, Cydrome Leader wrote:
> amdx <amdx@knology.net> wrote:
>> On 7/1/2020 12:13 PM, dagmargoodboat@yahoo.com wrote:
>>> On Tuesday, June 30, 2020 at 9:14:53 AM UTC-4, amdx wrote:
>>>> On 6/29/2020 8:33 AM, amdx wrote:
>>>>> On 6/28/2020 8:55 PM, Phil Allison wrote:
>>>>>> Robert Roland wrote:
>>>>>>
>>>>>> ====================
>>>>>>
>>>>>>>
>>>>>>> An unloaded transformer is almost entirely inductive, so the PF will
>>>>>>> be very low. As the load increases, the PF will also increase. This is
>>>>>>> normal. All transformer are like that.
>>>>>>>
>>>>>> ** If the same tranny is undergoing core saturation, the current wave
>>>>>> is highly distorted and maxima tend to co-incide with zero crossings -
>>>>>> exacerbating the poor PF.
>>>>>>
>>>>>>
>>>>>>
>>>>>>> One thing to look out for with MOTs, is that they are run very "hard",
>>>>>>> i.e. they magnetize the core well into saturation. That way, the
>>>>>>> manufacturers can save on iron, which saves on weight, which saves on
>>>>>>> cost. Since the MOT is normally run at fairly low duty cycle, and with
>>>>>>> fan cooling, they can get away with that. You may find that the
>>>>>>> transformer with zero load will draw 100 W or more of real power. If
>>>>>>> you leave it running for some amount of time, it will get very hot.
>>>>>>> The remedy for this is to add some additional turns to the primary
>>>>>>> winding. This will, of course, require you to add some additional
>>>>>>> secondary turns to reach the output voltage you want.
>>>>>>>
>>>>>>> Intuitively, you might think that adding more primary turns would
>>>>>>> increase the magnetization, therefore worsen the saturation situation.
>>>>>>> The reason it does not, is that the added windings increase the
>>>>>>> inductance of the primary winding, which results in a reduction in
>>>>>>> magnetizing current. The current reduces relatively more than the
>>>>>>> increase in turns.
>>>>>>>
>>>>>> ** Magnetisation goes up and down with the number of primary turns and
>>>>>> applied voltage while inductance follows the square of the number of
>>>>>> turns.
>>>>>>
>>>>>>
>>>>>>
>>>>>> .....?? Phil
>>>>>>
>>>>>
>>>>> ??I have graphed the Voltage and Current of the original primary winding
>>>>> and after adding 37 Turns, 48 Turns and 60 Turns.
>>>>> Any comments?
>>>>>> https://www.dropbox.com/s/0n1y4yh5o0j2sg6/mot%20primary%20voltage%20vs%20current%202%20graphs.jpg?dl=0
>>>>>>
>>>>>
>>>>> ?????????????????????????????????????????????????????????????????????????????????????????????????????? Mikek
>>>>>
>>>>>
>>>>
>>>>
>>>> I haven't got any response to the graphs, so without that, I'm going
>>>> to go with adding 60 primary turns, adjust the secondary to get the proper
>>>> secondary voltage and see if it delivers the required voltage at 8 amps.
>>>
>>> Great graphs.
>>>
>>> The first graph showed the virgin transformer was saturating (losing
>>> inductance) at 90 volts, where the current eyeballs-out to be about
>>> 20% higher than the straight-line slope beforehand.
>>>
>>> To my eyeball, aided with a ruler, the 62-extra-turns version hits
>>> that same 20% inductance loss / 20% "extra" current at about 115VAC.
>>> That looks reasonable to me.
>>
>>
>> Thanks for the input, Maybe I should have added a few more turns my
>> voltage runs about 122Vac. It's to late now, I have dipped and baked the
>> coils in an electric motor varnish, assembled it and then after assembly
>> dipped and baked the whole thing. Tomorrow, I will weld the core
>> sections together.
>> For those that don't know, MOTs are are one stacked E section and one
>> stacked I section that are welded along each outside edge. I just cut
>> the welds with a hack saw so I could install my coils.
>>
>> Mikek
>>
>
> I'd be interested to see photos of the finished transformer. The last one
> I messed with took way longer to cut the secondary winding out of than I
> expected. Was using a hacksaw and chisel and hammer. It wasn't as easy as
> it looks like in motor rewinding videos on youtube.
>
It's not pretty, it's well insulated, coils have been triple dipped in
varish and baked, the whole transformer dipped once. I don't hear any
vibration, so it looks good so far.
Here are the pics, FWIW.
> On Wed, 1 Jul 2020 18:34:30 -0500, amdx <amdx@knology.net> wrote:
>
>> Tomorrow, I will weld the core
>> sections together.
>
> I believe I read somewhere that you should not do that. With an
> ordinary welder, you will be putting enough heat into the core to risk
> damage to the insulation between the layers of steel in the core. The
> factory welding technique is extremely fast, so that much less heat is
> required.
>
> Firmly clamping them together was the recommendation.
>
I read your post an hour to late.
I welded it, tested it, first no noise with a 7.4 amp ac load.
The output is 21.9 Vac at 7.4 amps. So it seems fine so far.
I forgot to incorporate diode drops into the calculations, so 2 or 3
more turns should have been installed. 0.55 Volts/turn.
I have some higher wattage resistors, I'll get those out and load it
for an hour to see if it gets hot. Normal run time will be less than 10
minutes.
Mikek
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