On Oct 3, 11:51*pm, terry wrote:
On Oct 2, 11:37*am, wrote:





On Oct 2, 4:29*am, raypsi wrote:

On Oct 1, 12:55*pm, terry wrote:

We recently modified such a power supply to get a single 12 volt DC
output at about 20 amps for a particular, amateur radio application..
In order to do so we had to load one of the 5 volt outputs with a
couple of amps in order to get the unit to work; but that's normal.

Hey terry

I did that very same thing loaded the 5volt with 5ohm at 5 watt.
Ran my TenTec 526 off the 12 volt side of the PC power supply.
I thought it was the sweetest thing since sliced bread. Then
people started telling me I had this strange background noise.
They asked me what was going on in my shack. I had this strange
eerie noise in my shack, so they thought. Wasn't in my shack per
say but it was the PC power supply. Nobody knew I was running
a PC supply to power my rig.

73 OM

n7zu

I also use a modified PC power supply with no problems. I did add a
filter removed
from a commercial computer SMPS. I don't know the values of the
components but its a Pi filter
and the inductor is wound on what looks like a ferrite rod. The caps
are some pretty big disk
that had the writing rubbed off of them a long time ago. As Grumpy put
it. I like to "Frankenstien"
some of my projects.

I have been giving some thought as to what it would take to modify a
PC power supply for HV use.
I have been thinking along two lines,

1 Connect a second step-up transformer before the rectifiers.
2 Replace the transformer with one with a HV winding putting a 5volt
winding on the new
transformer for loading and feedback.

Jimmie- Hide quoted text -

- Show quoted text -

Great info: Thanks for all the ideas and especially about the warning
that the HV would be on the line side (input) from115/230 volt mains.
Unless a 60 hertz full isolation transformer were used; the weight and
size of which sort of negates the idea of using a lighter weight SPS!

I too used to fix TVs without power transformers, using selenium
rectifiers (boy could they stink!) and voltage doubler circuits to
provide B+. That was back in the mid late 1950s. I also made up a
little B+ power supply in a box clipped in during house calls to show
a customer that the problem was indeed inside the chassis and it had
to be taken away for a 'bench job'!

By that and means of never charging for a house call if I didn't fix
the set in situ; built up a reputation for straightforward dealing
which, despite the slightly funny accent of a British immigrant to
Canada, some 15 years later, may have helped me become elected to the
areas first town council? And that in a day and age when TV repairmen
didn't have the best reputation in the world (well at least around
here) for ethical dealings!

These days customers are a lot more cynical and questioning; and
rightly so!

BTW first heard about SPS in the telephone industry, before PC were
common; when power supplier representatives started telling us about
'rectifier/power supplies' that had efficiencies of over 80%.- Hide quoted text -

- Show quoted text -

The 300 volts you wanted is on the input side of the power supply, not
what you wanted. This does not mean that the output of the power
supply is not isolated from the mains. The type of switching power
supply you wanted is probably doable. Think about removing the output
transformer from a PC power supply and connecting it back to back with
the transformer in a working power supply. The output could be
rectified and filtered and you would have a cheap to free lightweight
line isolated HV power supply. I am in thr process of trying this. I
not getting much work done on it due to my present work schedule but
in a few weeks things should get back to normal and I will have a
chance to play with my toys some more.

I am just getting in to SMPSs and find it amazing what these things
willl do.
For example I found a a +- 15 volt unit that puts out 100 amps for
each voltage. I can hold the output transformers in my hand, they
couldnt weigh more than a pound each.

Jimmie

wrote:
On Oct 3, 11:51 pm, terry wrote:
On Oct 2, 11:37 am, wrote:





On Oct 2, 4:29 am, raypsi wrote:
On Oct 1, 12:55 pm, terry wrote:
We recently modified such a power supply to get a single 12 volt DC
output at about 20 amps for a particular, amateur radio application.
In order to do so we had to load one of the 5 volt outputs with a
couple of amps in order to get the unit to work; but that's normal.
Hey terry
I did that very same thing loaded the 5volt with 5ohm at 5 watt.
Ran my TenTec 526 off the 12 volt side of the PC power supply.
I thought it was the sweetest thing since sliced bread. Then
people started telling me I had this strange background noise.
They asked me what was going on in my shack. I had this strange
eerie noise in my shack, so they thought. Wasn't in my shack per
say but it was the PC power supply. Nobody knew I was running
a PC supply to power my rig.
73 OM
n7zu
I also use a modified PC power supply with no problems. I did add a
filter removed
from a commercial computer SMPS. I don't know the values of the
components but its a Pi filter
and the inductor is wound on what looks like a ferrite rod. The caps
are some pretty big disk
that had the writing rubbed off of them a long time ago. As Grumpy put
it. I like to "Frankenstien"
some of my projects.
I have been giving some thought as to what it would take to modify a
PC power supply for HV use.
I have been thinking along two lines,
1 Connect a second step-up transformer before the rectifiers.
2 Replace the transformer with one with a HV winding putting a 5volt
winding on the new
transformer for loading and feedback.
Jimmie- Hide quoted text -
- Show quoted text -
Great info: Thanks for all the ideas and especially about the warning
that the HV would be on the line side (input) from115/230 volt mains.
Unless a 60 hertz full isolation transformer were used; the weight and
size of which sort of negates the idea of using a lighter weight SPS!

I too used to fix TVs without power transformers, using selenium
rectifiers (boy could they stink!) and voltage doubler circuits to
provide B+. That was back in the mid late 1950s. I also made up a
little B+ power supply in a box clipped in during house calls to show
a customer that the problem was indeed inside the chassis and it had
to be taken away for a 'bench job'!

By that and means of never charging for a house call if I didn't fix
the set in situ; built up a reputation for straightforward dealing
which, despite the slightly funny accent of a British immigrant to
Canada, some 15 years later, may have helped me become elected to the
areas first town council? And that in a day and age when TV repairmen
didn't have the best reputation in the world (well at least around
here) for ethical dealings!

These days customers are a lot more cynical and questioning; and
rightly so!

BTW first heard about SPS in the telephone industry, before PC were
common; when power supplier representatives started telling us about
'rectifier/power supplies' that had efficiencies of over 80%.- Hide quoted text -

- Show quoted text -

The 300 volts you wanted is on the input side of the power supply, not
what you wanted. This does not mean that the output of the power
supply is not isolated from the mains. The type of switching power
supply you wanted is probably doable. Think about removing the output
transformer from a PC power supply and connecting it back to back with
the transformer in a working power supply. The output could be
rectified and filtered and you would have a cheap to free lightweight
line isolated HV power supply. I am in thr process of trying this. I
not getting much work done on it due to my present work schedule but
in a few weeks things should get back to normal and I will have a
chance to play with my toys some more.

I am just getting in to SMPSs and find it amazing what these things
willl do.
For example I found a a +- 15 volt unit that puts out 100 amps for
each voltage. I can hold the output transformers in my hand, they
couldnt weigh more than a pound each.

Jimmie

Pretty slick let us know how it works out.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

You might find this useful Jimmie.

I had some time to cobble together a DC-DC "transformer" this weekend.
It is a half-bridge running at 200KHz and fixed 96% duty cycle. The
turns ratio is 1:24 and the output is full wave rectified. I'm using
an EDT29 core, I think the material is 3C90.

The rectified AC line was ~160V and the output was ~1800V (I'm using
a Simpson 260 so the voltages are thereabout.)

After running 300 watts though it for two hours the transformer wasn't
near warm. If I take this further I need to build a real load.
A bucket of distilled water and some magnesium sulfate (epsom salt)
isn't stable when it's boiling.

It's a small transformer and light. It's not regulated but I think it
could replace a much larger laminated steel transformer.

Takes a rainy day for me to find any motivation for stuff like this.
Maybe after winter arrives I'll build it up properly and try it in
the SB200.

73



wrote in
:

The 300 volts you wanted is on the input side of the power supply, not
what you wanted. This does not mean that the output of the power
supply is not isolated from the mains. The type of switching power
supply you wanted is probably doable. Think about removing the output
transformer from a PC power supply and connecting it back to back with
the transformer in a working power supply. The output could be
rectified and filtered and you would have a cheap to free lightweight
line isolated HV power supply. I am in thr process of trying this. I
not getting much work done on it due to my present work schedule but
in a few weeks things should get back to normal and I will have a
chance to play with my toys some more.

I am just getting in to SMPSs and find it amazing what these things
willl do.
For example I found a a +- 15 volt unit that puts out 100 amps for
each voltage. I can hold the output transformers in my hand, they
couldnt weigh more than a pound each.

Jimmie

On Oct 5, 9:11*pm, Grumpy The Mule wrote:
You might find this useful Jimmie.

I had some time to cobble together a DC-DC "transformer" this weekend.
It is a half-bridge running at 200KHz and fixed 96% duty cycle. The
turns ratio is 1:24 and the output is full wave rectified. I'm using
an EDT29 core, I think the material is 3C90.

The rectified AC line was ~160V and the output was ~1800V (I'm using
a Simpson 260 so the voltages are thereabout.)

After running 300 watts though it for two hours the transformer wasn't
near warm. *If I take this further I need to build a real load.
A bucket of distilled water and some magnesium sulfate (epsom salt)
isn't stable when it's boiling.

It's a small transformer and light. *It's not regulated but I think it
could replace a much larger laminated steel transformer.

Takes a rainy day for me to find any motivation for stuff like this.
Maybe after winter arrives I'll build it up properly and try it in
the SB200.

73

wrote :



The 300 volts you wanted is on the input side of the power supply, not
what you wanted. This does not mean that the output of the power
supply is not isolated from the mains. The type of switching power
supply you wanted is probably doable. Think about removing the output
transformer from a PC power supply and connecting it back to back with
the transformer in a working power supply. The output could be
rectified and filtered and you would have a cheap to free lightweight
line isolated HV power supply. I am in thr process of trying this. I
not getting much work done on it due to my present work schedule but
in a few weeks things should get back to normal and I will have a
chance to play with my toys some more.

I am just getting in to SMPSs and find it amazing what these things
willl do.
For example I found a a +- 15 volt unit that puts out 100 amps for
each voltage. I can hold the output transformers in my hand, they
couldnt weigh more than a pound each.

Jimmie- Hide quoted text -

- Show quoted text -

Grumpy , when David Smith was testing out the uwave oven power supply
he use a big russian made triode as a dummy load.
Forgot the #, GS 35B or something like that. I was going to get one,
use it for a dummy load now and later build an amp if I dont blow it
up.
Jimmie

On Oct 5, 9:11*pm, Grumpy The Mule wrote:
You might find this useful Jimmie.

I had some time to cobble together a DC-DC "transformer" this weekend.
It is a half-bridge running at 200KHz and fixed 96% duty cycle. The
turns ratio is 1:24 and the output is full wave rectified. I'm using
an EDT29 core, I think the material is 3C90.

The rectified AC line was ~160V and the output was ~1800V (I'm using
a Simpson 260 so the voltages are thereabout.)

After running 300 watts though it for two hours the transformer wasn't
near warm. *If I take this further I need to build a real load.
A bucket of distilled water and some magnesium sulfate (epsom salt)
isn't stable when it's boiling.

It's a small transformer and light. *It's not regulated but I think it
could replace a much larger laminated steel transformer.

Takes a rainy day for me to find any motivation for stuff like this.
Maybe after winter arrives I'll build it up properly and try it in
the SB200.

73

wrote :



The 300 volts you wanted is on the input side of the power supply, not
what you wanted. This does not mean that the output of the power
supply is not isolated from the mains. The type of switching power
supply you wanted is probably doable. Think about removing the output
transformer from a PC power supply and connecting it back to back with
the transformer in a working power supply. The output could be
rectified and filtered and you would have a cheap to free lightweight
line isolated HV power supply. I am in thr process of trying this. I
not getting much work done on it due to my present work schedule but
in a few weeks things should get back to normal and I will have a
chance to play with my toys some more.

I am just getting in to SMPSs and find it amazing what these things
willl do.
For example I found a a +- 15 volt unit that puts out 100 amps for
each voltage. I can hold the output transformers in my hand, they
couldnt weigh more than a pound each.

Jimmie- Hide quoted text -

- Show quoted text -

I had a little time yesterday and opened up a PC power supply and
brought the 3 taps off of the transformer out to binding post. The
plan is to build a transformer that will step the voltage back up to
about 800 volts or so, enough for my little 6146B 6M amp.

Jimmie.

JImmie

On Oct 6, 10:40*pm, wrote:
On Oct 5, 9:11*pm, Grumpy The Mule wrote:





You might find this useful Jimmie.

I had some time to cobble together a DC-DC "transformer" this weekend.
It is a half-bridge running at 200KHz and fixed 96% duty cycle. The
turns ratio is 1:24 and the output is full wave rectified. I'm using
an EDT29 core, I think the material is 3C90.

The rectified AC line was ~160V and the output was ~1800V (I'm using
a Simpson 260 so the voltages are thereabout.)

After running 300 watts though it for two hours the transformer wasn't
near warm. *If I take this further I need to build a real load.
A bucket of distilled water and some magnesium sulfate (epsom salt)
isn't stable when it's boiling.

It's a small transformer and light. *It's not regulated but I think it
could replace a much larger laminated steel transformer.

Takes a rainy day for me to find any motivation for stuff like this.
Maybe after winter arrives I'll build it up properly and try it in
the SB200.

73

wrote :

The 300 volts you wanted is on the input side of the power supply, not
what you wanted. This does not mean that the output of the power
supply is not isolated from the mains. The type of switching power
supply you wanted is probably doable. Think about removing the output
transformer from a PC power supply and connecting it back to back with
the transformer in a working power supply. The output could be
rectified and filtered and you would have a cheap to free lightweight
line isolated HV power supply. I am in thr process of trying this. I
not getting much work done on it due to my present work schedule but
in a few weeks things should get back to normal and I will have a
chance to play with my toys some more.

I am just getting in to SMPSs and find it amazing what these things
willl do.
For example I found a a +- 15 volt unit that puts out 100 amps for
each voltage. I can hold the output transformers in my hand, they
couldnt weigh more than a pound each.

Jimmie- Hide quoted text -

- Show quoted text -

Grumpy , when David Smith was testing out the uwave oven power supply
he use a big russian made triode as a dummy load.
Forgot the #, GS 35B or something like that. I was going to get one,
use it for a dummy load now and later build an amp if I dont blow it
up.
Jimmie- Hide quoted text -

- Show quoted text -

should have been GU 35B

What will you use for an inductor in the output filter
following the second transformer?



wrote in
:

I had a little time yesterday and opened up a PC power supply and
brought the 3 taps off of the transformer out to binding post. The
plan is to build a transformer that will step the voltage back up to
about 800 volts or so, enough for my little 6146B 6M amp.

Jimmie.

On Oct 8, 7:47*pm, Grumpy The Mule wrote:
What will you use for an inductor in the output filter
following the second transformer?

wrote :



I had a little time yesterday and opened up a PC power supply and
brought the 3 taps off of the transformer out to binding post. The
plan is to build a transformer that will step the voltage back up to
about 800 volts or so, enough for my little 6146B 6M amp.

Jimmie.- Hide quoted text -

- Show quoted text -

Like you said I like to Frankenstien things. I have a filter from
another power supply but I am not sure how well it will work
as it was designed for about 25 amps. Basically thats a bridge I will
jump off of when I come to it. Right now I am having enough trouble
finding an old PC power supply I can get a transformer from. Its hard
to believe about a couple of months ago I tossed about a dozen of
them. Last time I listen to my wife. I do have a couple of
transformers from some old Lambda power supplies. Thes are some really
nice ones probably capable of handling a couple of Kwatts. Im not
ready to experiment with them yet. Although this is learning by
destuction it's cautious destruction. I will probably take a trip down
to the local computer place this weekend and do a little dumpster
diving or make a run on the goodwill store and see what I can get for
$10. IF you havent figured it out by now I love building things from
others discards. When I was in high schooI I built a killer stereo, I
thought at the time, from old stuff I found in the dump that was the
envy of most of my friends. Ive enjoyed doing it ever since.

Jimmie

Jimmie

Cobbling stuff together is lots of fun. From Pressman's
book you can figure out the inductor value.

I'm guessing a powdered iron toroid from the output of a PC
power supply would work. Probably need quite a few turns of
moderate size ~22AWG magnet wire. Maybe 300 turns... ugh.
Makes my hands hurt just thinking about it. I guess a bobbin
wound inductor would be better. Gapped ferrite isn't bad!

Check this site http://schmidt-walter.eit.h-da.de/smps_e/smps_e.html

I try to stay away from dumpsters but if I see anything electrical
or electronic in one it's neigh impossible.



wrote in
:

Like you said I like to Frankenstien things. I have a filter from
another power supply but I am not sure how well it will work
as it was designed for about 25 amps. Basically thats a bridge I will
jump off of when I come to it. Right now I am having enough trouble
finding an old PC power supply I can get a transformer from. Its hard
to believe about a couple of months ago I tossed about a dozen of
them. Last time I listen to my wife. I do have a couple of
transformers from some old Lambda power supplies. Thes are some really
nice ones probably capable of handling a couple of Kwatts. Im not
ready to experiment with them yet. Although this is learning by
destuction it's cautious destruction. I will probably take a trip down
to the local computer place this weekend and do a little dumpster
diving or make a run on the goodwill store and see what I can get for
$10. IF you havent figured it out by now I love building things from
others discards. When I was in high schooI I built a killer stereo, I
thought at the time, from old stuff I found in the dump that was the
envy of most of my friends. Ive enjoyed doing it ever since.

Jimmie

On Oct 9, 11:11*pm, Grumpy The Mule wrote:
Cobbling stuff together is lots of fun. *From Pressman's
book you can figure out the inductor value. *

I'm guessing a powdered iron toroid from the output of a PC
power supply would work. *Probably need quite a few turns of
moderate size ~22AWG magnet wire. *Maybe 300 turns... *ugh.
Makes my hands hurt just thinking about it. *I guess a bobbin
wound inductor would be better. *Gapped ferrite isn't bad!

Check this sitehttp://schmidt-walter.eit.h-da.de/smps_e/smps_e.html*

I try to stay away from dumpsters but if I see anything electrical
or electronic in one it's neigh impossible.

wrote :





Like you said I like to Frankenstien things. I have a filter from
another power supply but I am not sure how well it will work
as it was designed for about 25 amps. Basically thats a bridge I will
jump off of when I come to it. Right now I am having enough trouble
finding an old PC power supply I can get a transformer from. Its hard
to believe about a couple of months ago I tossed about a dozen of
them. Last time I listen to my wife. I do have a couple of
transformers from some old Lambda power supplies. Thes are some really
nice ones probably capable of handling a couple of *Kwatts. Im not
ready to experiment with them yet. Although this is learning by
destuction it's cautious destruction. I will probably take a trip down
to the local computer place this weekend and do a little dumpster
diving or make a run on the goodwill store and see what I can get for
$10. IF you havent figured it out by now I love building things from
others discards. When I was in high schooI *I built a killer stereo, I
thought at the time, from old stuff I found in the dump that was the
envy of most of my friends. Ive enjoyed doing it ever since.

Jimmie- Hide quoted text -

- Show quoted text -

From what I gather fro mthe website there is little danger in making L
to large within reason so I can expect my bits and pieces removed from
old power supplies to work. If they dont its probably because its too
small.


Jimmie