JW wrote:
Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard AC
plug at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for 1.25A.
Getting lots of irrelevant hits on google...

Thanks.


http://www.news-leader.com/article/2...elor-sentenced

A former camp counselor who pleaded guilty to sexually abusing several
children received two life sentences plus 30 years in prison on Wednesday.

Peter D. Newman, who worked at Kanakuk Kamps near Branson, was given the
sentence by Circuit Judge Mark Orr in Taney County after testimony from
a pair of psychologists, a Kanakuk staff member, a friend of Newman's,
two of his brothers and Newman himself.

Victims and their families did not testify at the hearing. They had
submitted written statements to Orr at an earlier time.

Newman had pleaded guilty in February to three counts of second-degree
statutory sodomy, two counts of first-degree statutory sodomy and two
counts of enticement of a child.

According to court records, Newman enticed children to join him for
"Bible studies" in a hot tub where they would engage in mutual masturbation.

At least one other victim said he and Newman performed oral and anal sex
on each other.

The victim also described Newman as his "spiritual mentor."

The abuse began when Newman first became a counselor in 1999 and
continued until 2009 when he was fired after camp administrators learned
of the allegations.

Newman's eight charges ultimately involved activity with six children.
However, Merrell said after the sentencing that Newman had admitted to
sexual activity with 13 other children as well. Many families chose not
to get involved.

"We won't try to force families to come forward," Merrell said.
"Particularly considering today's sentence."

Newman's attorney, Tom Carver, said he was disappointed in the outcome.

"I think it was a pretty severe sentence, given Pete's promising ability
to be amenable to treatment," he said.

A psychologist specializing in sex offender issues, Joseph Plaud, had
testified that Newman was a good candidate for treatment.

Another psychologist, Anna Salter, who testified for the state, said
that Newman could pose a danger because he had been able to abuse
children for a decade without being caught.

Newman also spoke to the judge and apologized for his actions.

"I was supposed to model Christ and I didn't," he said, fighting back
tears. "I made him look bad."

Taney County Prosecutor Jeff Merrell told Orr that Newman was "the most
prolific child molester" he's been aware of.

Taney County Sheriff Jimmie Russell said it was a difficult case to
investigate, both personally and logistically.

"It's hard on the investigators, the families and the victims," he said.

He said he was satisfied with the sentence and that it makes a strong
message to the community that Newman's behavior is not tolerated.

"What's upsetting is that he used religion to groom these kids for his
sexual gratification," he said. "That's very upsetting."

Merrell could not specify when Newman would be eligible for parole, but
he said it would be a long time.

Newman still could face charges in Colorado where he committed some of
his crimes at another Kanakuk camp.

Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard AC
plug at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for 1.25A.
Getting lots of irrelevant hits on google...

Thanks.

In article ,
JW wrote:
Can anyone recommend a good isolation transformer for sale on-line? Need
one that will handle 5 amps or so at 120VAC, and have a standard AC plug
at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for
1.25A. Getting lots of irrelevant hits on google...

I'm in the UK so it's 240 volts, but found it a lot cheaper to buy the
transformer bare and box it up myself. They're not a mass produced device
like say a 240 - 110 type so that may be the reason.

They used to be common for stage etc use, but RCDs etc seem to have
replaced them. As well as safer electronic instrument design.

They might well come up on Ebay secondhand, though.

--
*When cheese gets its picture taken, what does it say? *

Dave Plowman London SW
To e-mail, change noise into sound.

JW wrote:
Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard AC
plug at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for 1.25A.
Getting lots of irrelevant hits on google...

Thanks.

I think the $100 and "good quality" exclude each other for a transformer
that size.

the smaller units as used with cash registers and POS systems tend to max
out at 4 amps.

is used is ok, look for stuff from acme, topaz, oneac, shape, powervar.
powervar even had some interesting ones based off toroidal tranformers if
you want the ooh and aah factor.

In article ,
Cydrome Leader wrote:
JW wrote:
Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard
AC plug at the outlet. Prefer one for less than $100 or so, unless
that seems unreasonable. Found one at Mouser for $114 but that's only
good for 1.25A. Getting lots of irrelevant hits on google...

Thanks.

I think the $100 and "good quality" exclude each other for a transformer
that size.

A 625VA toroidal in the UK would cost about 50 gbp as a bare unit.
Slightly more for a one off.

--
*Never underestimate the power of stupid people in large groups.

Dave Plowman London SW
To e-mail, change noise into sound.

In article , Cydrome Leader wrote:
JW wrote:
Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard AC
plug at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for 1.25A.
Getting lots of irrelevant hits on google...

Thanks.

I think the $100 and "good quality" exclude each other for a transformer
that size.

the smaller units as used with cash registers and POS systems tend to max
out at 4 amps.

is used is ok, look for stuff from acme, topaz, oneac, shape, powervar.
powervar even had some interesting ones based off toroidal tranformers if
you want the ooh and aah factor.

Not cheap. Surplus Sales of Nebraska has some.

Depending on what your going to do, check if it has the secondary to ground bonding
which you should remove if you are seaking ground isolation.

greg

GregS wrote:
In article , Cydrome Leader wrote:
JW wrote:
Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard AC
plug at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for 1.25A.
Getting lots of irrelevant hits on google...

Thanks.

I think the $100 and "good quality" exclude each other for a transformer
that size.

the smaller units as used with cash registers and POS systems tend to max
out at 4 amps.

is used is ok, look for stuff from acme, topaz, oneac, shape, powervar.
powervar even had some interesting ones based off toroidal tranformers if
you want the ooh and aah factor.

Not cheap. Surplus Sales of Nebraska has some.

I'd avoid surplus sales. Why pay twice new prices for old stuff when you
don't have to?

It's an interesting place browse, and I've been there in person, but the
ripoff factor is pretty incredible.

"JW"

Can anyone recommend a good isolation transformer for sale on-line?

** What kind ??

There are two:

1. Galvanic isolation - for use on a service bench.

2. Neutral conductor isolation.

Most you see offered for sale in the USA are of the *second* kind.



..... Phil

On 6/10/2010 4:57 PM, Cydrome Leader wrote:
wrote:
In , Cydrome wrote:
wrote:
Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard AC
plug at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for 1.25A.
Getting lots of irrelevant hits on google...

Thanks.

I think the $100 and "good quality" exclude each other for a transformer
that size.

the smaller units as used with cash registers and POS systems tend to max
out at 4 amps.

is used is ok, look for stuff from acme, topaz, oneac, shape, powervar.
powervar even had some interesting ones based off toroidal tranformers if
you want the ooh and aah factor.

Not cheap. Surplus Sales of Nebraska has some.

I'd avoid surplus sales. Why pay twice new prices for old stuff when you
don't have to?

It's an interesting place browse, and I've been there in person, but the
ripoff factor is pretty incredible.



Surplus sales has its place in the food chain. Its NOT a salvage place
that just haphazardly throws stuff in piles, its all gone through
sorted,labeled and cataloged. Lots of nice old ham gear stuff if you
into it. Yea, most of it is not cheap. but try to find some of it from
other sources. Some of the stuff they have will NEVER sell at the prices
they have it at. Everyone knows how hot tube oscilloscopes are.....

With the number of shops closing, i would wait for a going out of
business sale or Ebay.

bob

JW wrote:
Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard
AC plug at the outlet. Prefer one for less than $100 or so, unless
that seems unreasonable. Found one at Mouser for $114 but that's only
good for 1.25A. Getting lots of irrelevant hits on google...

Thanks.

You could always salvage a couple of microwave oven transformers and connect
them back to back. Make sure and disconnect the secondaries from the cores
though, of course.

Jon

"Jon Danniken"

You could always salvage a couple of microwave oven transformers and
connect them back to back. Make sure and disconnect the secondaries from
the cores though, of course.


** Massively STUPID idea.

Absolutely WILL NOT WORK.



...... Phil

On Thu, 10 Jun 2010 09:44:12 -0400, JW wrote:

Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard AC
plug at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for 1.25A.
Getting lots of irrelevant hits on google...

Thanks.


MCM Electronics has one. Chuck

In article ,
Phil Allison wrote:

"JW"

Can anyone recommend a good isolation transformer for sale on-line?

** What kind ??

There are two:

1. Galvanic isolation - for use on a service bench.

2. Neutral conductor isolation.

Most you see offered for sale in the USA are of the *second* kind.



.... Phil

Surely an isolation transformer is just that - a one to one device with DC
isolation between windings. How it is subsequently configured is a
different matter. One use is where you can't be sure the line and neutral
of the supply are connected correctly - if they have a ground reference.

--
*To be intoxicated is to feel sophisticated, but not be able to say it.

Dave Plowman London SW
To e-mail, change noise into sound.

"Chuck"


MCM Electronics has one.


** One what ??




..... Phil

Referring to one (1) of 'em

I think

Yep, they have 'em.

--
Cheers,
WB
..............


"Phil Allison" wrote in message
...

"Chuck"


MCM Electronics has one.


** One what ??




.... Phil

bob wrote:
On 6/10/2010 4:57 PM, Cydrome Leader wrote:
wrote:
In , Cydrome wrote:
wrote:
Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard AC
plug at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for 1.25A.
Getting lots of irrelevant hits on google...

Thanks.

I think the $100 and "good quality" exclude each other for a transformer
that size.

the smaller units as used with cash registers and POS systems tend to max
out at 4 amps.

is used is ok, look for stuff from acme, topaz, oneac, shape, powervar.
powervar even had some interesting ones based off toroidal tranformers if
you want the ooh and aah factor.

Not cheap. Surplus Sales of Nebraska has some.

I'd avoid surplus sales. Why pay twice new prices for old stuff when you
don't have to?

It's an interesting place browse, and I've been there in person, but the
ripoff factor is pretty incredible.



Surplus sales has its place in the food chain. Its NOT a salvage place
that just haphazardly throws stuff in piles, its all gone through
sorted,labeled and cataloged. Lots of nice old ham gear stuff if you
into it. Yea, most of it is not cheap. but try to find some of it from
other sources. Some of the stuff they have will NEVER sell at the prices
they have it at. Everyone knows how hot tube oscilloscopes are.....

With the number of shops closing, i would wait for a going out of
business sale or Ebay.

bob

I think the whole basis for surplus sales is the guy has a really large
building, and can store infinite amounts of crap inside it forever.
Storing something there for decades doesn't seem to waste any space or
compete with shelf space for stuff that does sell.

It's a fun place to checkout if you're ever in Omaha. Lots of stuff on the
floor you can walk around isn't on the website.

Unfortunately the next best place like that that was in chicago called the
Radio TV Lab closed years ago. It was a serious time machine in there. The
guy had NIB replacement parts for wire recorders- and not ones from
planes, but from before magnetic tape worked at all, plus service guides
for pretty much anything with tubes in it. Getting in and out of the shop
was a single file line type operation and people having to all leave to
let customers out wasn't uncommon. Stuff was stacked to the ceilings in
every direction. If you needed a part that wasn't current it was there.

Maybe somebody here knows what this-

He had some sort of capacitor that looked like a large can electrolytic
but it was filled with liquid that sloshed around. I don't recall the
ratings at all.

It was explained that if shaken, and if the case started to feel colder
the cap was still good, sort of like an chemical ice pack.

Does anybody have any idea what sort of capacitor this was?

Jon Danniken wrote:
JW wrote:
Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard
AC plug at the outlet. Prefer one for less than $100 or so, unless
that seems unreasonable. Found one at Mouser for $114 but that's only
good for 1.25A. Getting lots of irrelevant hits on google...

Thanks.

You could always salvage a couple of microwave oven transformers and connect
them back to back. Make sure and disconnect the secondaries from the cores
though, of course.

Jon



I've been tempted to try that just to see how awful the regulation is and
what sort of waveform would even come out before the things burned up.

In article , "Dave Plowman (News)" wrote:
In article ,
Phil Allison wrote:

"JW"

Can anyone recommend a good isolation transformer for sale on-line?

** What kind ??

There are two:

1. Galvanic isolation - for use on a service bench.

2. Neutral conductor isolation.

Most you see offered for sale in the USA are of the *second* kind.



.... Phil

Surely an isolation transformer is just that - a one to one device with DC
isolation between windings. How it is subsequently configured is a
different matter. One use is where you can't be sure the line and neutral
of the supply are connected correctly - if they have a ground reference.


An isolation transfor is typically 1:1.1 in real life.
Its acts as 1:1 with FULL load. Well all transformers are rated FULL LOAD.

They really need to start calling these things different names.
A regular "isolation transformer", and they should not be calling it that,
is NOT ground isolated since the secondary is tied to ground.
The purpose of this transformer is noise reduction, period, using an isolation
transformer.

Find another name.

greg

In article ,
GregS wrote:
They really need to start calling these things different names. A
regular "isolation transformer", and they should not be calling it that,
is NOT ground isolated since the secondary is tied to ground. The
purpose of this transformer is noise reduction, period, using an
isolation transformer.

In the UK the secondary of a (safety) isolating transformer is *not* tied
to ground - that would entirely defeat the purpose.

So someone needs to invent a new name for your type. ;-)

--
*Funny, I don't remember being absent minded.

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman "Pommy Nutcase"

Phil Allison
"JW"

Can anyone recommend a good isolation transformer for sale on-line?

** What kind ??

There are two:

1. Galvanic isolation - for use on a service bench.

2. Neutral conductor isolation.

Most you see offered for sale in the USA are of the *second* kind.


Surely an isolation transformer is just that...


** Shame it is not in the USA - you steaming great ****wit.



.... Phil

"Wild_Bill"


MCM Electronics has one.


** One what ??

The question is not about the number but the nature of the item.


.... Phil

In article ,
Phil Allison wrote:
Surely an isolation transformer is just that...


** Shame it is not in the USA - you steaming great ****wit.

Given your supreme command of the English language it's not a surprise you
don't understand what 'isolate' means...

--
*I don't suffer from insanity -- I'm a carrier

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 11 Jun 2010 10:30:56 +1000 "Phil Allison"
wrote in Message id: :


"JW"

Can anyone recommend a good isolation transformer for sale on-line?

** What kind ??

There are two:

1. Galvanic isolation - for use on a service bench.

Galvanic. Thanks - didn't realize there are different kinds. Don't want to
kill myself!

In article ,
JW wrote:
On Fri, 11 Jun 2010 10:30:56 +1000 "Phil Allison"
wrote in Message id: :


"JW"

Can anyone recommend a good isolation transformer for sale on-line?

** What kind ??

There are two:

1. Galvanic isolation - for use on a service bench.

Galvanic. Thanks - didn't realize there are different kinds. Don't want
to kill myself!

It certainly seems to me stupid to have the same name for different
devices like this. What is the point of an isolating transformer which
doesn't isolate?

--
*When a clock is hungry it goes back four seconds*

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 11 Jun 2010 08:24:36 -0500 Chuck wrote in Message
id: :

On Thu, 10 Jun 2010 09:44:12 -0400, JW wrote:

Can anyone recommend a good isolation transformer for sale on-line?
Need one that will handle 5 amps or so at 120VAC, and have a standard AC
plug at the outlet. Prefer one for less than $100 or so, unless that seems
unreasonable. Found one at Mouser for $114 but that's only good for 1.25A.
Getting lots of irrelevant hits on google...

Thanks.


MCM Electronics has one. Chuck

Thanks Chuck. Looking at these for the moment:
http://www.mcmelectronics.com/produc...S500-/28-10160
http://www.mcmelectronics.com/produc...-1097-/72-1097

A bit more than I wanted to spend and a little less current capability,
but those may be the breaks.

On Sat, 12 Jun 2010 06:53:47 -0400, JW wrote:

...
Nice price. I'm working on a 1KW HP 6032A power supply (with outputs
unloaded in this case, so I don't need *too* much current capability) and
need to connect my scope to the hot side of a switching transformer -
specifically the source and drains on the output FETs.

Service manual: (3MB)
http://www.home.agilent.com/agilent/...=-35687.384731
Page 113 shows the schematic of the FET board.

With an isolation transformer, I *think* I would connect the scopes GND
lead the source of Q1 and probe the it's gate to check the it, then move
the scopes GND lead to Q3's drain lead to check it's gate drive.

Given that, would that Ebay transformer be the right choice, and do I need
to isolate (disconnect) the ground on the 6032A power supply under repair?

Thanks.

You need to make 100% sure your life insurance is fully paid up. g

"JW" wrote in message
...

Nice price. I'm working on a 1KW HP 6032A power supply (with outputs
unloaded in this case, so I don't need *too* much current capability) and
need to connect my scope to the hot side of a switching transformer -
specifically the source and drains on the output FETs.

Service manual: (3MB)
http://www.home.agilent.com/agilent/...=-35687.384731
Page 113 shows the schematic of the FET board.

With an isolation transformer, I *think* I would connect the scopes GND
lead the source of Q1 and probe the it's gate to check the it, then move
the scopes GND lead to Q3's drain lead to check it's gate drive.

Given that, would that Ebay transformer be the right choice, and do I need
to isolate (disconnect) the ground on the 6032A power supply under repair?

Thanks.

This is a "bad idea". Better to use a differential input and two probes. Do
you have a two channel scope with invert on channel 2?

Tom

"Dave Plowman " Rabid Pommy Nutcase"


Can anyone recommend a good isolation transformer for sale on-line?

** What kind ??

There are two:

1. Galvanic isolation - for use on a service bench.

2. Neutral conductor isolation.

Most you see offered for sale in the USA are of the *second* kind.


Surely an isolation transformer is just that...


** Shame it is not so in the USA

- you Steaming Great ****wit ...............




.... Phil

In article ,
Phil Allison wrote:
Surely an isolation transformer is just that...


** Shame it is not so in the USA

- you Steaming Great ****wit ...............

But I'm not in the USA and neither are you. However, at least I know not
to use bad language when visiting. If you'd ever known your parents they'd
have likely taught you the same.

--
*If at first you don't succeed, redefine success.

Dave Plowman London SW
To e-mail, change noise into sound.

On Sat, 12 Jun 2010 10:32:04 -0400, "tm" wrote:


"JW" wrote in message
.. .

Nice price. I'm working on a 1KW HP 6032A power supply (with outputs
unloaded in this case, so I don't need *too* much current capability) and
need to connect my scope to the hot side of a switching transformer -
specifically the source and drains on the output FETs.

Service manual: (3MB)
http://www.home.agilent.com/agilent/...=-35687.384731
Page 113 shows the schematic of the FET board.

With an isolation transformer, I *think* I would connect the scopes GND
lead the source of Q1 and probe the it's gate to check the it, then move
the scopes GND lead to Q3's drain lead to check it's gate drive.

Given that, would that Ebay transformer be the right choice, and do I need
to isolate (disconnect) the ground on the 6032A power supply under repair?

Thanks.

This is a "bad idea". Better to use a differential input and two probes. Do
you have a two channel scope with invert on channel 2?

Tom


That would be news to large numbers of electronics technicians who had
to use an isolation transformer when servicing TVs and other 'live
chassis' consumer electronics. There IS a reason the advice was 'to
always keep one hand in your pocket'.

PlainBill

On Sat, 12 Jun 2010 10:20:10 -0700, PlainBill47 �ʇoɹ�:

On Sat, 12 Jun 2010 10:32:04 -0400, "tm" wrote:


"JW" wrote in message
. ..

Nice price. I'm working on a 1KW HP 6032A power supply (with outputs
unloaded in this case, so I don't need *too* much current capability)
and need to connect my scope to the hot side of a switching
transformer - specifically the source and drains on the output FETs.

Service manual: (3MB)
http://www.home.agilent.com/agilent/redirector.jspx?
action=ref&cname=AGILENT_EDITORIAL&ckey=1000000384-1%3Aepsg%
3Aman&lc=eng&cc=US&nfr=-35687.384731
Page 113 shows the schematic of the FET board.

With an isolation transformer, I *think* I would connect the scopes
GND lead the source of Q1 and probe the it's gate to check the it,
then move the scopes GND lead to Q3's drain lead to check it's gate
drive.

Given that, would that Ebay transformer be the right choice, and do I
need to isolate (disconnect) the ground on the 6032A power supply
under repair?

Thanks.

This is a "bad idea". Better to use a differential input and two
probes. Do you have a two channel scope with invert on channel 2?

Tom


That would be news to large numbers of electronics technicians who had
to use an isolation transformer when servicing TVs and other 'live
chassis' consumer electronics. There IS a reason the advice was 'to
always keep one hand in your pocket'.

PlainBill

Serviced many GE VIR portables with a Sencore PR57 Powerite.

In article ,
wrote:
That would be news to large numbers of electronics technicians who had
to use an isolation transformer when servicing TVs and other 'live
chassis' consumer electronics. There IS a reason the advice was 'to
always keep one hand in your pocket'.

If using a proper isolating transformer, there will be no reference to
ground even with a 'live' chassis. The only way to get an electrical shock
is to touch both outputs from the transformer.

--
*Why isn't there a special name for the back of your knee?

Dave Plowman London SW
To e-mail, change noise into sound.

wrote in message
...
On Sat, 12 Jun 2010 10:32:04 -0400, "tm" wrote:


"JW" wrote in message
. ..

Nice price. I'm working on a 1KW HP 6032A power supply (with outputs
unloaded in this case, so I don't need *too* much current capability)
and
need to connect my scope to the hot side of a switching transformer -
specifically the source and drains on the output FETs.

Service manual: (3MB)
http://www.home.agilent.com/agilent/...=-35687.384731
Page 113 shows the schematic of the FET board.

With an isolation transformer, I *think* I would connect the scopes GND
lead the source of Q1 and probe the it's gate to check the it, then move
the scopes GND lead to Q3's drain lead to check it's gate drive.

Given that, would that Ebay transformer be the right choice, and do I
need
to isolate (disconnect) the ground on the 6032A power supply under
repair?

Thanks.

This is a "bad idea". Better to use a differential input and two probes.
Do
you have a two channel scope with invert on channel 2?

Tom


That would be news to large numbers of electronics technicians who had
to use an isolation transformer when servicing TVs and other 'live
chassis' consumer electronics. There IS a reason the advice was 'to
always keep one hand in your pocket'.

PlainBill

You can do it anyway you want. Just that many good scopes have a way to add
the inverted second channel and can be used to look at a signal that is
raised above
ground. No isolation transformer is needed and it is IMO, safer.


YMMV.

Apparently you assume that I didn't understand that.

--
Cheers,
WB
..............


"Phil Allison" wrote in message
...


The question is not about the number but the nature of the item.


.... Phil

wrote:

On Sat, 12 Jun 2010 10:32:04 -0400, "tm" wrote:


"JW" wrote in message
.. .

Nice price. I'm working on a 1KW HP 6032A power supply (with outputs
unloaded in this case, so I don't need *too* much current capability) and
need to connect my scope to the hot side of a switching transformer -
specifically the source and drains on the output FETs.

Service manual: (3MB)
http://www.home.agilent.com/agilent/...=-35687.384731
Page 113 shows the schematic of the FET board.

With an isolation transformer, I *think* I would connect the scopes GND
lead the source of Q1 and probe the it's gate to check the it, then move
the scopes GND lead to Q3's drain lead to check it's gate drive.

Given that, would that Ebay transformer be the right choice, and do I need
to isolate (disconnect) the ground on the 6032A power supply under repair?

Thanks.

This is a "bad idea". Better to use a differential input and two probes. Do
you have a two channel scope with invert on channel 2?

Tom


That would be news to large numbers of electronics technicians who had
to use an isolation transformer when servicing TVs and other 'live
chassis' consumer electronics. There IS a reason the advice was 'to
always keep one hand in your pocket'.


That advice was quite valid when two channel scopes weren't seen
outside of a factory or research center.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

"Dave Plowman (News)" wrote:

In article ,
wrote:
That would be news to large numbers of electronics technicians who had
to use an isolation transformer when servicing TVs and other 'live
chassis' consumer electronics. There IS a reason the advice was 'to
always keep one hand in your pocket'.

If using a proper isolating transformer, there will be no reference to
ground even with a 'live' chassis. The only way to get an electrical shock
is to touch both outputs from the transformer.


Not true. You connect the chassis of the UUT to the test equipment,
so ANY voltage you contact inside the UUT is referenced to ground.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

"tm"

You can do it anyway you want. Just that many good scopes have a way to
add
the inverted second channel and can be used to look at a signal that is
raised above ground.

** The problem with that idea is the very limited common mode range
available with that scope function.

The buffers on most ( analogue) scopes become overloaded with input signals
that exceed full screen hight by a factor of 2 or 3 times.

Say you want to examine a 1 volt p-p signal and you set the scope input
atten to 0.5 volts per division - then the largest undistorted input
allowable is gonna be about 0.5 x 8 x 3 = 12 volts p-p.

Not much use with the ACTUAL common mode signal is several hundred volts p-p
from rectified AC supply.


No isolation transformer is needed and it is IMO, safer.

** Fraid that is just not true when dealing with off-line SMPS.



..... Phil

"Dave Plowman " Rabid Pommy Nutcase"

Phil Allison

Surely an isolation transformer is just that...


** Shame it is not so in the USA

- you Steaming Great ****wit ...............

But I'm not in the USA and neither are you.


** But the OP is in the *** USA *** !!!!!!!!!!!

- and he asked for a 120 volt AC tranny too !!!!!!!!!


You colossal, ****ing POMMY MORON !!!


..... Phil

"Wild_Bill Top Poster from Hell"

Apparently you assume that I didn't understand that.


** Could not be plainer that you did NOT understand the issue.




"Phil Allison"

The question is not about the number but the nature of the item.


.... Phil

My point, which you missed, was that you're not going to teach anyone proper
grammer or composition on usenet.. if you think otherwise, you're mistaken.

--
Cheers,
WB
..............

See?.. top-posted again. Always have, always will




"Phil Allison" wrote in message
...

"Wild_Bill Top Poster from Hell"

Apparently you assume that I didn't understand that.


** Could not be plainer that you did NOT understand the issue.




"Phil Allison"

The question is not about the number but the nature of the item.


.... Phil