Isolated, regulated, toroidal step down transformer AC power supply design. - Page 10

wow. you really are making life difficult for yourself. Of course it
doesnt take much to attract flames, but I would recommend a strategy
other than begging for them.

For the record, as Trevor has repeatedly pointed out, regulating AC is
actually pretty hard. and 1% is an astonishingly tight spec - assuming
closed-loop control, you will need a reference that is quite a bit
better than 1% (all the other tolerances stack up), *all* the relevant
components in the feedback sensing loop will need to be < 1% etc. It is
most assuredly *NOT* a "simple thing".

If you really insist on it, then why not make a variable inductor, using
an E-core. Place this in series with the 9Vac output, and devise a
controller which increases the inductance as the line voltage increases,
and vice-versa. A suitable variable inductor is pretty easy - a pair of
windings on each outer leg, in series and phased such that the
centre-leg flux cancels. Then place a winding around the centre-leg, and
run DC through it. Enough DC will make the core saturate, and the total
AC inductance will drop to the air-cored value; no DC and the inductance
will be maximised.

but if you cant measure ripple current, I doubt you can make one of
these (although it is straightforward to make such a system which will
meet your requirements)

I say this as an experienced power supply design engineer, not some
amateur. If a customer came to me with this request, I would spend some
time trying to ascertain (by asking questions and getting more
information) what the real problem is, then work towards solving that.
And if the customer insisted I do what they asked, I would wave goodbye
and then have a good laugh, swapping the story with mates over a beer,
whilst maligning clue-free customers.

Cheers
Terry

you probably only need larger heatsinks on the regulators, higher voltager
reservoir capacitors and a slightly higher AC voltage input




it does not.





here's another way.
        
                  .-||-+------------+------||--.
                  |    |            |          |
                  |    |        o---+---o      |
        F1        |    |     _-~         ~-_   |
      .-oxo-------+----|--+-~ : o---+---o : ~--+-----
      |                |  |   :     |     :    |
    --+-oxo-. ||| _____|  |  |~|    |    |~|   |
        F2   3|||(_      === |\|    |    |\|  ===   out
 "240V"      3|||(_ 36V   |  |_|    |    |_|   |    240V +/- 9%
  +/-24%     3|||(________|_________|__________|    
    --+-----' |||             ry1        ry2
      |       TR1           "+15%"      "-15%"
      `---------------------------------------------

activating relay 1 will boost the output voltage by 15%  use it when the
input goes past 8% low relay 2 will reduce the output by 15%, use it when the
input goes past 8% high, the circuit to tetect over or undervoltage and
switch on the apropriate relay is not shown.

the relays should be rated to handle switching 48VAC and have atleast 1000V
isolation,  the fuses   ( --oxo-- in the diagram ) sdhould be rated
apropriately for thr transformer,  the capacitors should be non-polarised
about 1uF seems a good size.

a circuit not completely unlike the above is used at the power sub-station
to regulate your power, but having it closer to the appliance means fewer
compromises need to be made.

You cruel bastard!!

What does it explain?

snipped-for-privacy@dodo.com.au says...


so just where does one place the magnetic shunt in a toroidal core for a
CVT?

besides, most of the people who used to design these have died.

snipped-for-privacy@dodo.com.au says...


(thinks....)

 Between the primary and secondary windings - same as an EI

(I'm guessing that'd mean a layer of GOSS between the primary and secondary
windings )

So a cross-section parallel to the windings would go, radially,
GOSS core,
insulation,
primary,
insulation,
GOSS shunt
insulation,
secondary



that could be a problem.

Does an R core really regulate much better than a toroidial, they still have
the primary wound on top of the secondary?

Bye.
   Jasen

**Nope.

 they still have


**Nope. That is what makes them excellent for low level audio applications.

"Trevor Wilson"
 "jasen"






** Many of then DO have the secondary wound directly over the primary.

  Only way to achieve the very low external mag fields.

  Not so good for safety,  though.



.......   Phil

**I stand corrected. Some are so configured.

snipped-for-privacy@dodo.com.au says...


excellent attempt! I dont think that would work overly well though....if
at all.



A+ for effort Jasen!

Cheers
Terry

**Why don't you tell us what you are trying to actually do, rather than
telling us what you think you need?

As you may have guessed, your request is difficult to satisfy.

At a minimum, you need to tell us:

* AC or DC
* Maximum and minimum current requirements.

I am trying to build a 240 VAC in (or even 110 VAC in, I really don't care)
9 VAC out, regulated (to 9 VAC) , isolated (from transformer), step down
transformer and AC power supply.

Input fused (at about 2 amps) but I could adapt just about any design to
about that current.

There...but I think I already said it, didn't I ..Let's see?




... yes, thats me.



......ah, I did.

What is the application?

Do you need a regulated 9V RMS Sinewave output? What for?????

James

Yes.

Say please.

**WHAT IS THE APPLICATION?

It's irrelevant, actually.

240 VAC in (nominal) , 9 VAC out (+/- 1%), about 2 amps (but you can make it
10 amps or 1 amp, I don't care), toroidal transformer.

I've already given you sufficient information on the type of circuit it
supplies.

**No, it is not irrlevant.



**Why do you specify a toroidal transformer?



**No, you have not. You have STILL not answered the many important questions
I've asked either.

Here's one:

What is the input Voltage on the regulators?

"Trevor Wilson"





**  Wake up  -  TW  !!!

The schizo bush maggot has not even got a DMM.






.......   Phil

    Even if he did, he'd probably try to measure how many ohms were
coming out of his plugpack.

Uni assignment?

Rudolf