isolation transformer needed

[GregS]

If one of those points is ground touching the other gives you a shock. If
neither is ground you can touch either one without a shock. The whole
principle of using an isolating transformer for safety. Makes for better
odds.

Its also necesary to make certain differential oscilloscope measurments if you don't
have a differential plug-in.

I also tend to use a battery scope for that instead.

greg

 

[GregS]

I'm looking for an isolation transformer for repairing small (less
than 1000W) power supplies. I see loads of them on ebay and some are
medical grade and inexpensive. Are these usable for what I want?
Other than that, any tips on where to get a good deal on one? I
don't want to spend a load as this is hobby work only.

One thing you don't hear mentioned too much about is voltage.
We all know transformers are rated for a voltage with load.
The same thing can apply to an isolation transformer. i
have ordered custom wired transformers, and its NOT 1:1 with
no load. They increase the voltage to make up for the loss.
In some applications the voltage may be too high after this.
Good to use a variac along with an isolation transformer and monitor
voltage and current.

greg

 

[David Lesher]

I'm looking for an isolation transformer for repairing small (less
than 1000W) power supplies. I see loads of them on ebay and some are
medical grade and inexpensive. Are these usable for what I want?
Other than that, any tips on where to get a good deal on one? I
don't want to spend a load as this is hobby work only.

Buy 2 transformers with 120V primaries, and some voltage secondaries.
Hook them back to back.

The weirder the secondary voltage, the lower the cost. Try all the usual
surplus suspects.

Of course the secondary power rating will be the limiting factor.

 

[Phil Allison]

"David Lesher"

Buy 2 transformers with 120V primaries, and some voltage secondaries.
Hook them back to back.

The weirder the secondary voltage, the lower the cost.

** That is a very unwise suggestion:

AC supply transformers are NOT intended to be operated in reverse - cos the
magnetising current is intended to be carried by the supply side winding and
NOT the secondary.

A standard 500VA transformer operating from 120 VAC may well draw 1.5 amps
with no load - no problem since as the primary winding has only about 0.6
ohms of resistance and hence loses only 1.35 watts in heat.

The iron core losses will far exceed that.

However, if you try to make it work in reverse to deliver 120 volts at 500VA
from the primary - things get nasty.

First, the secondary will have to be fed with a ** higher voltage** than
the **off load** voltage by about 4% to cover voltage drop under load.

Naturally this increases the previously mentioned magnetising current level
by about 30%.

So now it is say 2 amps, referred to the primary.

2 amps at 120 volts = 240VA and that HAS to be *continuously supplied* by
the first tranny in the pair.

So, the result is that the pair of trannys can only deliver half the VA into
the load that one is capable of.


..... Phil

 

[David Lesher]

** That is a very unwise suggestion:

AC supply transformers are NOT intended to be operated in reverse - cos the
magnetising current is intended to be carried by the supply side winding and
NOT the secondary.

I've used this approach several times in the past, and never had
the catastrophe you imply. I recall doing it with a pair of plate
transformers [600V at 200-300 mA]; and later with some weird 60V@6A ones.

The idle currents were not egregious, and given the broad range of
"120 volt line" the loss unobtrusive. It was surely safer than working
on hot-chassis equipment without same.

 

[Phil Allison]

"David Lesher"
"Phil Allison"

I've used this approach several times in the past, and never had
the catastrophe you imply.

** Try reading my post again.

Only fuckwits snip posts out of site so they can write idiot
comments like you just did.

No "catastrophe" was predicted by me.

Anyone can claim to have done something wacky and got
away with it.

Sorry to say that is ** ABSOLUTELY NO BASIS **
for advising others in a public forum.
----------------------------------------------------------------

Some years back, I tried connecting a pair of new 240V / 6.3V, 15VA
transformers back to back to get an isolated 240 V output. The first tranny
in the pair ran hot with no load on the second.

A 15 watt load on the second dropped the voltage from 240V to 200V and the
first tranny then got very hot.

Testing revealed that the current drawn from the first tranny by the second
nearly equalled to its 15VA rating.

Useless.


..... Phil

 

[bz]

"David Lesher"



** That is a very unwise suggestion:

I am sorry to have to say this, but that statement is wrong.

AC supply transformers are NOT intended to be operated in reverse - cos
the magnetising current is intended to be carried by the supply side
winding and NOT the secondary.

The magnetic flux density depends on current AND the number of turns.

Less turns and higher current gives the same flux density.

This is why 'ampere-turns' are used in calculating flux density, not simply
'amps'.
http://mysite.du.edu/~jcalvert/tech/transfor.htm

The magnetic core doesn't care which winding induces the magnetic field.

A standard 500VA transformer operating from 120 VAC may well draw 1.5
amps with no load

At what phase? With no load, it is NOT in phase. It DOES cause IR losses in
the primary, however.

- no problem since as the primary winding has only
about 0.6 ohms of resistance and hence loses only 1.35 watts in heat.

1.5 amps at 120 volts = 180 W
1.5 amps at 120 volts at 89.57 degrees (or a power factor of 0.993) gives
1.35 watts.

Slightly over 1% loss. That is a bit high for modern power transformers
under no load, but a normal loss under max rated load.

The iron core losses will far exceed that.

Shouldn't. The iron core losses are PART of the total losses seen.

However, if you try to make it work in reverse to deliver 120 volts at
500VA from the primary - things get nasty.

No. You should only, at worst (approximately) double the losses (assuming
two identical transformers).

Let us assume that the secondary of T1 is 12 vac.
To deliver 500VA at 12 volts, the secondary is going need to see a 0.288
ohm load and will deliver 41.7 amps to the load. The DC resistance of the
winding will be much lower than the load resistance, on the order of 0.03
ohms for an inefficient transformer.

First, the secondary will have to be fed with a ** higher voltage**
than the **off load** voltage by about 4% to cover voltage drop under
load.

Naturally this increases the previously mentioned magnetising current
level by about 30%.

The identical but reversed 2nd transformer 'expects' that higher voltage
and exactly compensates for it.

So now it is say 2 amps, referred to the primary.

Wrong. If the output of the second transformer is carrying 1 amp, the
primary of the first transformer will carry 1 amp plus the iron and copper
losses of the two transformers. A poor efficiency is about 95% so with two
transformers, back to back, you might expect 10% losses resulting in 1.10
amps.

A low voltage, high current secondary is commonly wound with heavier wire
so it can stand more current and presents a much lower dc resistance.
When it is driven, as when the windings are reversed, it will run just
fine.

2 amps at 120 volts = 240VA and that HAS to be *continuously supplied*
by the first tranny in the pair.

Wrong. Only the current to supply the 'no load losses' needs to be supplied
'continuously'.

Under the 500VA load, the primary will present a 28.8 ohm load to the
110VAC line, drawing 4.2 amps of current while the back to back 12 volt
windings will be carrying 42 amps of current.

The no load losses will be quite low because the primary presents an
essentially pure inductive load rather than a resistive load to the ac
line. Only the core losses, on the order of .25 to .5% of the rating will
need to be supplied.

http://findarticles.com/p/articles/mi_m0BPR/is_10_21/ai_n6259812/

Under no load, the 12 volt windings would see a 'parasitic current' on the
order of 0.02 Amps and the 110 V primary would see a current on the order
of 0.1 Amp and present a 'resistive component' of the load of 115 ohms to
the supply lines.

So, the result is that the pair of trannys can only deliver half the VA
into the load that one is capable of.

The combo should be able to supply close to the rated VA of
_a_single_transformer.

You will have ~twice the losses and both transformers will reach the
temperature that one would have reached.

So, de-rate the pair of 500VA back to back transformers to 450VA to give
yourself plenty of safety margin and don't seal them into an airtight box
together, and you should be just fine.

.... Phil

Best Regards

 

[Jamie]

I am sorry to have to say this, but that statement is wrong.




The magnetic flux density depends on current AND the number of turns.

Less turns and higher current gives the same flux density.

This is why 'ampere-turns' are used in calculating flux density, not simply
'amps'.
http://mysite.du.edu/~jcalvert/tech/transfor.htm

The magnetic core doesn't care which winding induces the magnetic field.




At what phase? With no load, it is NOT in phase. It DOES cause IR losses in
the primary, however.




1.5 amps at 120 volts = 180 W
1.5 amps at 120 volts at 89.57 degrees (or a power factor of 0.993) gives
1.35 watts.

Slightly over 1% loss. That is a bit high for modern power transformers
under no load, but a normal loss under max rated load.




Shouldn't. The iron core losses are PART of the total losses seen.




No. You should only, at worst (approximately) double the losses (assuming
two identical transformers).

Let us assume that the secondary of T1 is 12 vac.
To deliver 500VA at 12 volts, the secondary is going need to see a 0.288
ohm load and will deliver 41.7 amps to the load. The DC resistance of the
winding will be much lower than the load resistance, on the order of 0.03
ohms for an inefficient transformer.




The identical but reversed 2nd transformer 'expects' that higher voltage
and exactly compensates for it.




Wrong. If the output of the second transformer is carrying 1 amp, the
primary of the first transformer will carry 1 amp plus the iron and copper
losses of the two transformers. A poor efficiency is about 95% so with two
transformers, back to back, you might expect 10% losses resulting in 1.10
amps.

A low voltage, high current secondary is commonly wound with heavier wire
so it can stand more current and presents a much lower dc resistance.
When it is driven, as when the windings are reversed, it will run just
fine.




Wrong. Only the current to supply the 'no load losses' needs to be supplied
'continuously'.

Under the 500VA load, the primary will present a 28.8 ohm load to the
110VAC line, drawing 4.2 amps of current while the back to back 12 volt
windings will be carrying 42 amps of current.

The no load losses will be quite low because the primary presents an
essentially pure inductive load rather than a resistive load to the ac
line. Only the core losses, on the order of .25 to .5% of the rating will
need to be supplied.

http://findarticles.com/p/articles/mi_m0BPR/is_10_21/ai_n6259812/

Under no load, the 12 volt windings would see a 'parasitic current' on the
order of 0.02 Amps and the 110 V primary would see a current on the order
of 0.1 Amp and present a 'resistive component' of the load of 115 ohms to
the supply lines.




The combo should be able to supply close to the rated VA of
_a_single_transformer.

You will have ~twice the losses and both transformers will reach the
temperature that one would have reached.

So, de-rate the pair of 500VA back to back transformers to 450VA to give
yourself plenty of safety margin and don't seal them into an airtight box
together, and you should be just fine.




Best Regards

Nice vanity call you have there Mr. N5BZ..

For some reason I have a vision of seeing you on slow scan?

 

[Phil Allison]

"bz"

** I'll give this very confused radio ham just one try.

I am sorry to have to say this, but that statement is wrong.

** You are a brave man - and a very foolish one too.

The magnetic core doesn't care which winding induces the magnetic field.

** Not relevant.

The issue is the magnetising CURRENT !!

Slightly over 1% loss.

** Nonsense.

The power loss is mostly from the iron core when there is no load.

The previously mentioned 1.5 amps of magnetising current is inversely
proportional to the number of turns on the core.

The iron core losses will far exceed that.

Shouldn't.

** Fraid it does - pal.

No.

** Fraid they do get nasty.

Even if nobody ever told you about it.

Let us assume that the secondary of T1 is 12 vac.
To deliver 500VA at 12 volts, the secondary is going need to see a 0.288
ohm load and will deliver 41.7 amps to the load. The DC resistance of the
winding will be much lower than the load resistance, on the order of 0.03
ohms for an inefficient transformer.


The identical but reversed 2nd transformer 'expects' that higher voltage
and exactly compensates for it.

** You have failed to see the issue of transformer "regulation", ie the
*off load* and *on load* secondary voltages are different - the voltage
always drops when load is applied. Ohms Law you know.

All transformers are wound so as to give the desired secondary voltage/s
when " on load" - ie the turns ratio is adjusted to compensate for the
regulation factor.

Wrong.

** Fraid it is quite true - pal.

If the output of the second transformer is carrying 1 amp,

** The discussion is still about the no load situation.

You are miles away from any understanding of the issue.

Wrong.

** Fraid it is correct - pal.

Only the current to supply the 'no load losses' needs to be supplied
'continuously'.

** That is exactly what I said.

Taking your example of a 12 volt secondary, the magnetising current drawn
when used in reverse is 10 times that when used the normal way. So, instead
of 1.5 or 2 amps of current - it is 15 or 20 amps.

Transformers are always rated in VA rather than watts - cos it is possible
to * fully load * a transformer with capacitance or inductance while drawing
no real power.

IOW - once the secondary *current rating* is reached, the game is up.

The no load losses will be quite low because the primary presents an
essentially pure inductive load rather than a resistive load to the ac
line. Only the core losses, on the order of .25 to .5% of the rating will
need to be supplied.

http://findarticles.com/p/articles/mi_m0BPR/is_10_21/ai_n6259812/

** How hysterically funny !!!!!!!!!!

The radio ham has quoted a page that discusses megawatt transformers the
size of houses.

Then he blithely assumes all transformers have the same characteristics as
these.

Wot a hoot.



...... Phil

 

[mike]

I'm looking for an isolation transformer for repairing small (less
than 1000W) power supplies. I see loads of them on ebay and some are
medical grade and inexpensive. Are these usable for what I want?
Other than that, any tips on where to get a good deal on one? I
don't want to spend a load as this is hobby work only.

You can certainly come up with a reason to have an isolation transformer.
But for most things, it's just a false sense of safety/security
that will let you convince yourself that it is reasonable to do
VERY UNSAFE things.

What matters is the DIFFERENTIAL voltage between two points.
If you float the mains, you still have that differential
and have gained nothing. To be safe, you still have to
put both hands in your pockets and leave them there.

So, you're bored standing there with your hands in your pockets.
Let's do some unsafe things! Let's make a measurement with the
oscilloscope. So, you grab the probe. Hey, what's this black wire
dangling from the probe? Let's hook it "here" in the circuit.
Doesn't matter where "here" is, you've now got a NOT FLOATING
power supply. What's worse, the normally isolated secondary side
may have a lot of common-mode volts on it. You're at risk of a
shock...AND...simultaneously blowing up your scope and anything
you're using for a load.

Well, we can't have that. Let's cut the ground pin on the scope power
cord. That'll fix it...wonder if they have WiFi in heaven so I can
report my progress???

If you want to work on power supplies, get yourself an isolated
scope probe. Or a portable scope with no metal parts designed
for that type of measurement.

Tektronix A6902 probe works well. I picked up mine at a garage sale for
a buck. I suspect they're substantially more from a dealer.

Using a DVM with well-insulated probes, you can tell if the
diodes are open or input
storage cap is defective or there's volts on the fet. Beyond
that, you really need more than an isolation transformer if you
expect to do it safely.

mike

 

[Phil Allison]

"mike the madman "

You can certainly come up with a reason to have an isolation transformer.

** Like being able to safety ground the chassis, speakers and tuner box of a
TV set that otherwise all sit at lethal voltages.

But for most things, it's just a false sense of safety/security

** Yep - never use one if the unit already has one.

What matters is the DIFFERENTIAL voltage between two points.
If you float the mains, you still have that differential
and have gained nothing.

** Pure insanity.

So, you're bored standing there with your hands in your pockets.
Let's do some unsafe things! Let's make a measurement with the
oscilloscope. So, you grab the probe. Hey, what's this black wire
dangling from the probe? Let's hook it "here" in the circuit.
Doesn't matter where "here" is, you've now got a NOT FLOATING
power supply.

** Any sane tech will simply ground the common ( negative line ) in the high
voltage part of the PSU.

Then proceed as usual for units that have internal isolation trannys.

What's worse, the normally isolated secondary side
may have a lot of common-mode volts on it.

** Totally insane BOLLOCKS.

Well, we can't have that. Let's cut the ground pin on the scope power
cord.

** Something only rabid lunatics like mike do.

Yawnnnnnnnnnnn........

If you want to work on power supplies, get yourself an isolated
scope probe. Or a portable scope with no metal parts designed
for that type of measurement.

Tektronix A6902 probe works well. I picked up mine at a garage sale for a
buck.

** Used examples sell for around $US1000 through on-line dealers.

More utter insanity.

I suspect they're substantially more from a dealer.

** Wot a posturing, bullshit artist.

Using a DVM with well-insulated probes, you can tell if the
diodes are open or input storage cap is defective or there's volts on the
fet. Beyond that, you really need more than an
isolation transformer if you expect to do it safely.

** Wot an obvious pile of crapology.

Typical of mug, 5V engineers way out of their depth.


...... Phil

 

[mike]

"mike the madman "



** Like being able to safety ground the chassis, speakers and tuner box of a
TV set that otherwise all sit at lethal voltages.



** Yep - never use one if the unit already has one.



** Pure insanity.



** Any sane tech will simply ground the common ( negative line ) in the high
voltage part of the PSU.

Then proceed as usual for units that have internal isolation trannys.



** Totally insane BOLLOCKS.




** Something only rabid lunatics like mike do.

Yawnnnnnnnnnnn........



** Used examples sell for around $US1000 through on-line dealers.

More utter insanity.



** Wot a posturing, bullshit artist.



** Wot an obvious pile of crapology.

Typical of mug, 5V engineers way out of their depth.


..... Phil

Creative snipping eh?

 

[Phil Allison]

"Andy the Honky "

On an isolation transformer (single phase), the primary side is always
grounded because the neutral leg is always bonded in the distribution
panel. This is a code requirement. If the secondary is also grounded
(I am pretty sure this is also a requirement), the two sides are still
electrically isolated.

** No way is it a requirement for 1:1 mains transformers used for " safety
isolation " or electrical / electronic servicing.

When you have no clue - shut the **** up.

This is NOT an opinion forum for morons.

Despite appearances.....



.... Phil

 

[Phil Allison]

"Dave Plowman (Nutcase)"

If your mains supply has one side grounded, then touching the 'live' side
causes a shock. If you use an isolating transformer, you can touch either
leg safely.

** Not if **anything** is earthing one of them -
like a scope or other test equipment ground.

Or an unknown fault in the equipment.

That plus an RCD feeding it provides the best degree of safety
in the workshop.

** Appalling BULLSHIT !!!

Once you add an isolation tranny in the AC supply

- RCDs do NOT work anymore !!!!
---------------------------------------------

Wot an ignorant pommy turd to say otherwise.

I'm surprised you don't see this.

** No surprise to anyone that Dave Fuckwit Powman is full of SHIT up to his
eyeballs.

The notion he describes is 100% FALSE and totally discredited many decades
ago as a very DANGEROUS practice.




..... Phil

 

[Phil Allison]

"Dave Plowman (Nutcase)"

If your mains supply has one side grounded, then touching the 'live' side
causes a shock. If you use an isolating transformer, you can touch either
leg safely.

** Not if **anything** is earthing one of them - like a scope or
other test equipment ground.

Or an unknown fault in the equipment grounds the incoming AC
or something linked to it.

That plus an RCD feeding it provides the best degree of safety
in the workshop.

** Appalling BULLSHIT !!!

Once you add an isolation tranny in the AC supply

- RCDs do NOT work anymore !!!!
---------------------------------------------

Wot an PIG ignorant pommy turd to say otherwise.

That insane notion will KILL someone !!!!

I'm surprised you don't see this.

** No surprise to anyone that Dave Fuckwit Powman is full of SHIT
up to his eyeballs.

The notion he describes is 100% FALSE and totally discredited
many decades ago as a very DANGEROUS practice.

Dave can go rot in HELL.



..... Phil

 

[mike]

If your mains supply has one side grounded, then touching the 'live' side
causes a shock. If you use an isolating transformer, you can touch either
leg safely. That plus an RCD feeding it provides the best degree of safety
in the workshop. I'm surprised you don't see this.

You amaze me.
You're so bent on proving me wrong that you
are not open to the possibility that applying
logic to misguided advice might yield useful
information.

Normally, I'd not waste my time trying to train
internet denizens. But in cases where a plethora
of misguided advice presented vehemently and with
AUTHORITY puts people at risk of DEATH,
I feel compelled to speak up. This stuff hangs
around for years.

So, back to your statement...with logic...

If you "touch" only one thing, it doesn't matter
whether you have an isolation transformer
or not. Problem is that touching one thing
provides no information beyond what you could
get using an insulated tool. You really don't need
to "touch" anything.

Electricity finds it's way to touch you through
paths you didn't anticipate.

How many of you woke up on the morning of your
electrocution and said, "today, I think I'll electrocute
myself"? Raise your hands high...oh, those of you
who committed suicide by electrocution can put your hands down.

This is the important part...my contribution to the thread...
Pay attention now:

The primary reason to want an isolation transformer to
troubleshoot a power supply is to work on the primary side.
Now, the KEY word is TROUBLESHOOT. What that means is that
the power supply has a FAULT in the primary circuit.
What's the fault? You don't know, or you'd just fix it.
How safe is it to troubleshoot that particular fault?
You don't know, 'cause you don't know what it is.

You're gonna RISK ELECTROCUTION based on the misguided
assumption that an isolation transformer keeps you safe.
YOU'RE NOT SAFE. YOU DON'T HAVE ANY IDEA WHAT THE PRIMARY
CIRCUIT IS, BECAUSE IT'S NOT AS DESIGNED. IT HAS A FAULT!!!!!!!
The node that the designer called common may not be common
at all. IT HAS A FAULT!!!! You should not arbitrarily ground
ANY node. It has a fault!!! (I'm skipping over the obvious
question, "what is ground anyway?")

An isolation transformer is not inherently bad. It can
provide a layer of protection. What is bad is the FALSE
sense of security
that the transformer makes it safe to poke around inside
a supply WITH A PRIMARY FAULT.

I'll say it one more time.

I don't care if you design power supplies in your sleep.
A FAILED power supply DOES NOT have the circuit that
was intended. It has a FAULT. A safety analysis based
on a working power supply and an isolation transformer
DOES NOT APPLY. Maybe you've always been lucky.
That's no cause to suggest to another that they can do what
you've been doing and NOT DIE.

 

[Phil Allison]

"Dave Plowman Ignorant Fucking Nutcase"

If your mains supply has one side grounded, then touching the 'live' side
causes a shock. If you use an isolating transformer, you can touch either
leg safely.

** Not if **anything** is earthing one of them - like a scope or
other test equipment ground.

Or an unknown fault in the equipment grounds the incoming AC
or something linked to it.

That plus an RCD feeding it provides the best degree of safety
in the workshop.

** Appalling BULLSHIT !!!

Once you add an isolation tranny in the AC supply

- RCDs do NOT work anymore !!!!
---------------------------------------------

Wot an PIG ignorant pommy turd to say otherwise.

That insane notion will KILL someone !!!!

I'm surprised you don't see this.

** No surprise to anyone that Dave Fuckwit Powman is full of
SHIT up to his eyeballs.

The notion he describes is 100% FALSE and totally discredited
many decades ago as a very DANGEROUS practice.

Dave can go rot in HELL.



..... Phil

 

[Phil Allison]

" Dave Plowman = Ignorant Fucking Nutcase"

If your mains supply has one side grounded, then touching the 'live' side
causes a shock. If you use an isolating transformer, you can touch either
leg safely.

** Not if **anything** is earthing one of them - like a scope or
other test equipment ground.

Or an unknown fault in the equipment grounds the incoming AC
or something linked to it.

That plus an RCD feeding it provides the best degree of safety
in the workshop.

** Appalling BULLSHIT !!!

Once you add an isolation tranny in the AC supply

- RCDs do NOT work anymore !!!!
---------------------------------------------

Wot an PIG ignorant pommy turd to say otherwise.

That insane notion will KILL someone !!!!

I'm surprised you don't see this.

** No surprise to anyone that Dave Fuckwit Powman is full of
SHIT up to his eyeballs.

The notion he describes is 100% FALSE and totally discredited
many decades ago as a very DANGEROUS practice.

Dave can go rot in HELL.




..... Phil

 

[David Nebenzahl]

On 12/30/2009 2:26 PM Phil Allison spake thus:

[snip abuse]

Phil: Take your fucking meds and SHUT UP!!!!!

 

[Phil Allison]

"Dave Plowman = Lying Pile of SHIT "

I've got no objection to anyone saying I'm wrong.

** You ALWAYS 100% WRONG !!!

And you HATE being told SOOOO much you ALWAYS attack the messenger.

Provided they back it up with facts.

** Problem being - YOU are such a TOTAL FUCKWIT

you have clue what the relevant facts are !!

You dismiss them every time as irrelevant and post DRIVEL instead.

Mains electricity is always dangerous. Using an isolation
transformer can *reduce* that hazard. Not *eliminate* it.

** It actually increases it in the service bench situation.

For reason that are forever incomprehensible to FUCKWITS like YOU !!

And as regards
connecting a grounded mains 'scope probe etc to equipment under repair
which you've fed via an isolating transformer - words fail me.

** In most case, the only reason for using a mains isolation tranny

is JUST SO YOU CAN DO THAT !!!!!!!

You fucking IGNORANT pommy TWAT !!

How the **** do you imagine folk fix off-line SMPS ???
----------------------------------------------------------------

You have ZERO electronics knowledge.

**** OFF AND DIE !!



.... Phil