power supply circuit

[F Murtz]

I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

 

[JW]

On Mon, 09 Jun 2008 22:42:37 +1000 F Murtz <haggisz@hotmail.com> wrote in
Message id: <484d2532@dnews.tpgi.com.au>:

I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

How about this one: http://www.national.com/mpf/LM/LM1084.html

 

[Tim Wescott]

F Murtz wrote:

I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

Regulated current or regulated voltage? Or do you want a lab-type
supply with regulated voltage and smooth current limiting?

It sounds like you don't have a tremendous amount of experience with
electronics -- you may find it helpful to get a copy of the ARRL
handbook, which has some nice power supply designs as well as a _lot_ of
good practical basic knowledge.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[MooseFET]

On Jun 9, 5:42 am, F Murtz <hagg...@hotmail.com> wrote:

I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

How much current do you want?

Lets just assume you make DC from the AC and then regulate down.

Doing a couple of figures for making 4A into lets say zero volts:

24V * sqrt(2) = 34V

34V * 4A = 136W

The the regulator circuit needs to get rid of 136W.

To do this, you need something like 10 TO-220 packages transistors
screwed down to a quite large chunk of fins.

If you have enough fin area, about 5 to 7 TIP-35 or TIP-36 transistors
would work for you.

Another question is how fast the current limiting or regulation needs
to act. A lot of very practical designs can make a large spike of
current when suddenly shorted. The power supply will easily survive
this but if the short was you connecting it to a diode, the diode may
be damaged.

Do you need instant (or nearly so) action on the current limiting?

Take a look at the LT3080:
http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1040,C1055,P38503

Notice how it lets you set the output voltage all the way down to
zero. This sort of design is a good place to start your thinking.

You can also think of the circuit as just a non-inverting op-amp
amplifying the output of the pot you use to set the voltage. This is
another good direction to go.

 

[rebel]

On Mon, 9 Jun 2008 07:55:58 -0700 (PDT), MooseFET <kensmith@rahul.net> wrote:

On Jun 9, 5:42 am, F Murtz <hagg...@hotmail.com> wrote:
I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful


How much current do you want?

Lets just assume you make DC from the AC and then regulate down.

Doing a couple of figures for making 4A into lets say zero volts:

24V * sqrt(2) = 34V

34V * 4A = 136W

The the regulator circuit needs to get rid of 136W.

Minor points - the transformer isn't rated to deliver 136W, and that 34V is
unloaded peak.

 

[MooseFET]

On Jun 9, 6:32 pm, rebel <m...@privacy.net> wrote:

On Mon, 9 Jun 2008 07:55:58 -0700 (PDT), MooseFET <kensm...@rahul.net> wrote:
On Jun 9, 5:42 am, F Murtz <hagg...@hotmail.com> wrote:
I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

How much current do you want?

Lets just assume you make DC from the AC and then regulate down.

Doing a couple of figures for making 4A into lets say zero volts:

24V * sqrt(2) = 34V

34V * 4A = 136W

The the regulator circuit needs to get rid of 136W.

Minor points - the transformer isn't rated to deliver 136W, and that 34V is
unloaded peak.

When working out the power in the regulator, it is best to assume that
the peak voltage is what you get. The rated voltage on the
transformer is for a normal line voltage. In the high line case, you
can get a little more.

 

[rebel]

On Tue, 10 Jun 2008 06:36:46 -0700 (PDT), MooseFET <kensmith@rahul.net> wrote:

On Jun 9, 6:32 pm, rebel <m...@privacy.net> wrote:
On Mon, 9 Jun 2008 07:55:58 -0700 (PDT), MooseFET <kensm...@rahul.net> wrote:
On Jun 9, 5:42 am, F Murtz <hagg...@hotmail.com> wrote:
I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

How much current do you want?

Lets just assume you make DC from the AC and then regulate down.

Doing a couple of figures for making 4A into lets say zero volts:

24V * sqrt(2) = 34V

34V * 4A = 136W

The the regulator circuit needs to get rid of 136W.

Minor points - the transformer isn't rated to deliver 136W, and that 34V is
unloaded peak.

When working out the power in the regulator, it is best to assume that
the peak voltage is what you get. The rated voltage on the
transformer is for a normal line voltage. In the high line case, you
can get a little more.

I appreciate that, but my original comments stand. There is no valid reason to
state "the regulator circuit needs to get rid of 136W" when the transformer is
not rated to deliver that power.

 

[F Murtz]

F Murtz wrote:

I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

Thanks to every one for their help on power supply design from spec
sheets etc but I was hoping for an already designed circuit

 

[Phil Allison]

"F Murtz" <haggisz@hotmail.com>

**Beware - cross-posting Hotmail wanker on the loose....

Thanks to every one for their help on power supply design from spec sheets
etc but I was hoping for an already designed circuit

** Do you still expect to get visits from the " tooth fairy " ???




...... Phil

 

[F Murtz]

Phil Allison wrote:

"F Murtz" <haggisz@hotmail.com

**Beware - cross-posting Hotmail wanker on the loose....


Thanks to every one for their help on power supply design from spec sheets
etc but I was hoping for an already designed circuit


** Do you still expect to get visits from the " tooth fairy " ???




..... Phil


Phil very sorry if cross posting is illegal but I thought different

people used different ngs other wise there would be only one and I
thought I would reach a greater audience.
If the only way to obtain a circuit for a power supply is to get a
degree in everything I suppose I should instead of asking on news groups

 

[Phil Allison]

"F Murtz" <haggisz@hotmail.com>

**Beware - cross-posting Hotmail wanker on the loose....


Thanks to every one for their help on power supply design from spec
sheets etc but I was hoping for an already designed circuit


** Do you still expect to get visits from the " tooth fairy " ???



Phil very sorry if cross posting is illegal but I thought different people
used different ngs other wise there would be only one and I thought I
would reach a greater audience.

** Yes dickhead - I do know why people cross post.

But it is the act of a troll and tedious Hotmail wankers who have no common
sense.

If the only way to obtain a circuit for a power supply is to get a degree
in everything I suppose I should instead of asking on news groups

** Someone as stupid as you will never learn anything.

Cos you ignore everything you don't want to hear.



...... Phil

 

[-=Spudley=-]

"F Murtz" <haggisz@hotmail.com> wrote in message
news:484F3906.4080401@hotmail.com...

Phil Allison wrote:
"F Murtz" <haggisz@hotmail.com

**Beware - cross-posting Hotmail wanker on the loose....


Thanks to every one for their help on power supply design from spec
sheets etc but I was hoping for an already designed circuit


** Do you still expect to get visits from the " tooth fairy " ???




..... Phil


Phil very sorry if cross posting is illegal but I thought different people
used different ngs other wise there would be only one and I thought I
would reach a greater audience.
If the only way to obtain a circuit for a power supply is to get a degree
in everything I suppose I should instead of asking on news groups.

Your first clue and News Groups life lesson is to ignore Phil and his
obsessive compulsive disorder driven, vitriol. (Killfile him, and your NG
life will be so much more pleasureable)

 

[legg]

On Wed, 11 Jun 2008 11:24:33 +1000, F Murtz <haggisz@hotmail.com>
wrote:

F Murtz wrote:
I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful


Thanks to every one for their help on power supply design from spec
sheets etc but I was hoping for an already designed circuit

It would be a pity, putting together your first power supply without
taking the oportunity to learn something about it. I mean - what are
you going to be using the completed power supply for, if not as a
learning tool?

A fair supply of app notes are available on the web to help you do
this, in consideration of the fact that you want to tailor the circuit
to transformers that you already have. Normally you wouldn't purchase
a part before you had some idea of what you needed, to do what you
aimed to do.

http://www.ieeta.pt/~alex/docs/ApplicationNotes/Rectifier%20Applications%20Handbook.pdf

A kit or pre-built/surplus unit may be an obvious alternative to the
bulk of all this 'learning' stuff. Even then, getting what you need
still requires an aim, to specify a requirement.

One kind of regulation method that is fairly tolerant of transformer
fixed winding voltages is illustrated at

http://members.shaw.ca/legg/1991a.html

This also offers a pspice simulation that runs in the free SWCADIII
package from Linear Technology. It takes a lot more savy to graft
regulation circuits onto un-anticipated transformers than it does to
design for a transformer from scratch, or fit a properly configured
transformer into a pre-designed configuration.

RL

 

[F Murtz]

legg wrote:

On Wed, 11 Jun 2008 11:24:33 +1000, F Murtz <haggisz@hotmail.com
wrote:

F Murtz wrote:
I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

Thanks to every one for their help on power supply design from spec
sheets etc but I was hoping for an already designed circuit

It would be a pity, putting together your first power supply without
taking the oportunity to learn something about it. I mean - what are
you going to be using the completed power supply for, if not as a
learning tool?

A fair supply of app notes are available on the web to help you do
this, in consideration of the fact that you want to tailor the circuit
to transformers that you already have. Normally you wouldn't purchase
a part before you had some idea of what you needed, to do what you
aimed to do.

http://www.ieeta.pt/~alex/docs/ApplicationNotes/Rectifier%20Applications%20Handbook.pdf

A kit or pre-built/surplus unit may be an obvious alternative to the
bulk of all this 'learning' stuff. Even then, getting what you need
still requires an aim, to specify a requirement.

One kind of regulation method that is fairly tolerant of transformer
fixed winding voltages is illustrated at

http://members.shaw.ca/legg/1991a.html

This also offers a pspice simulation that runs in the free SWCADIII
package from Linear Technology. It takes a lot more savy to graft
regulation circuits onto un-anticipated transformers than it does to
design for a transformer from scratch, or fit a properly configured
transformer into a pre-designed configuration.

RL
Thanks I will look into what you have said.

The reason for using these transformers is that I already have them. I
did not buy them They were disused equipment

 

[Phil Allison]

"F Murtz"

It takes a lot more savy to graft
regulation circuits onto un-anticipated transformers than it does to
design for a transformer from scratch, or fit a properly configured
transformer into a pre-designed configuration.
Thanks I will look into what you have said.
The reason for using these transformers is that I already have them. I did
not buy them They were disused equipment

** We BLOODY know that - you steaming great half-wit.

Got any sows ears you want to make into purses ??





...... Phil

 

[Bill Bowden]

On Jun 9, 5:42 am, F Murtz <hagg...@hotmail.com> wrote:

I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

Look up the LM338 three terminal regulator. It's rated at 5 amps and
35 volts from output to input. All you need is a couple resistors or a
pot to set the output voltage. Use a 10 amp bridge rectifier to
convert the transformer secondary AC to DC and a 20,000uF, or
thereabouts filter cap. Connect the capacitor to the (+) input of the
regulator and ground and adjust the resistors for the desired output
votage. The regulator also has current limiting, but not sure what it
is. You can get 1.2 volts to maybe 24 volts DC out, but you need a
large heat sink when the output is set low and drawing 5 amps.

-Bill

 

[F Murtz]

Phil Allison wrote:

"F Murtz"
It takes a lot more savy to graft
regulation circuits onto un-anticipated transformers than it does to
design for a transformer from scratch, or fit a properly configured
transformer into a pre-designed configuration.
Thanks I will look into what you have said.
The reason for using these transformers is that I already have them. I did
not buy them They were disused equipment


** We BLOODY know that - you steaming great half-wit.

Got any sows ears you want to make into purses ??





..... Phil



I do not know what your problem is but I was explaining the free

transformers to Legg who seemed to think that I bought the transformers
and then wanted a circuit

 

[Phil Allison]

"F Murtz"
It takes a lot more savy to graft
regulation circuits onto un-anticipated transformers than it does to
design for a transformer from scratch, or fit a properly configured
transformer into a pre-designed configuration.
Thanks I will look into what you have said.
The reason for using these transformers is that I already have them. I
did not buy them They were disused equipment


** We BLOODY know that - you steaming great half-wit.

Got any sows ears you want to make into purses ??



I do not know what your problem is

** YOU are the one with all the problems - dickhead.

but I was explaining the free

transformers to Legg who seemed to think that I bought the transformers
and then wanted a circuit

** Yet another of your mindless false assumptions.

Go away, fool.



..... Phil

 

[Herbert John \"Jackie\" G]

On Wed, 11 Jun 2008 19:43:29 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

"F Murtz"
It takes a lot more savy to graft
regulation circuits onto un-anticipated transformers than it does to
design for a transformer from scratch, or fit a properly configured
transformer into a pre-designed configuration.
Thanks I will look into what you have said.
The reason for using these transformers is that I already have them. I
did not buy them They were disused equipment


** We BLOODY know that - you steaming great half-wit.

Got any sows ears you want to make into purses ??



I do not know what your problem is


** YOU are the one with all the problems - dickhead.

but I was explaining the free
transformers to Legg who seemed to think that I bought the transformers
and then wanted a circuit


** Yet another of your mindless false assumptions.

Go away, fool.



.... Phil



What a hilarious thread!

"I have this pile of shit, and I want to turn it into a magical box...
does anyone have any shit-to-box diagrams out there?"

I am sorry, but I have to side with Phil on this one.

Go buy a power supply learning tool kit from Radio Shack. Sheesh!

 

[legg]

On Wed, 11 Jun 2008 14:29:43 +1000, F Murtz <haggisz@hotmail.com>
wrote:

legg wrote:
On Wed, 11 Jun 2008 11:24:33 +1000, F Murtz <haggisz@hotmail.com
wrote:

F Murtz wrote:
I would like to make an adjustable power supply using a transformer with
a 24v 5a single wound secondary I would like the voltage to be
adjustable from lowest to highest possible given transformer I would
like to have regulated current

There is another possibility I also have a larger transformer with two
32v 4.7a secondaries If anyone has a schematic for an adjustable power
supply with adjustable current regulation making the most of the
transformer specs I would be eternally grateful

Thanks to every one for their help on power supply design from spec
sheets etc but I was hoping for an already designed circuit
snip
A fair supply of app notes are available on the web to help you do
this, in consideration of the fact that you want to tailor the circuit
to transformers that you already have. Normally you wouldn't purchase
a part before you had some idea of what you needed, to do what you
aimed to do.

http://www.ieeta.pt/~alex/docs/ApplicationNotes/Rectifier%20Applications%20Handbook.pdf

snip
Thanks I will look into what you have said.
The reason for using these transformers is that I already have them. I
did not buy them They were disused equipment

The Motorola handbook will give a good idea about what your
transformers are capable of, and how they might be configured to give
different output voltages to suit a post regulator. That will be your
first step, and give you your options.

RL