Can anyone recommend a chip to convert 24V DC to 48V DC? Someone told
they exist and that the output current would be half the input current
in order to double the output voltage. I'm bulding a phantom power supply.

H wrote:
Can anyone recommend a chip to convert 24V DC to 48V DC? Someone told
they exist and that the output current would be half the input current
in order to double the output voltage. I'm bulding a phantom power supply.

I don't think that anyone makes a chip like this yet, but there are
some chips that are the guts of a DC-DC converter (which is what you
have to build) that are designed to use with a transformer and some
external components.

You might want to read this document and the "charge pump" application
note from the same web site:
http://www.maxim-ic.com/appnotes.cfm...te_number/2031

Unless this is for a portable (battery powered) application, you'll get
where you want to be a whole lot sooner if you just buy a commercial
phantom power supply or build one using a transformer and rectifier. Or
make/buy a battery phantom power supply. Five 9V batteries in series
will power most mics for a day or so (but test it before you go too far
from a 7-11).

"H" wrote in message
news:YlzVe.168745$wr.73319@clgrps12

Can anyone recommend a chip to convert 24V DC to 48V DC?

If you check the schematics of commercial mic preamps, you
will find that that function is often done with no chips at
all, or with a standard off-the-shelf chip like a 555 timer
acting as a source of high frequency, low voltage pulses
that feed into a traditional voltage-multiplier power
supply.

Someone told they exist and that the output current would
be half the
input current in order to double the output voltage.

Conservation of energy is a rather robust physical law. ;-)

JP Gerard wrote:

I'd suggest getting a proper 48VDC supply...

I would have to agree here. For a 48V output, you are probably going to need
an inductor based step-up converter -- not an easy thing to design or
build.

H wrote:
Can anyone recommend a chip to convert 24V DC to 48V DC? Someone told
they exist and that the output current would be half the input current
in order to double the output voltage. I'm bulding a phantom power supply.

Google for DC-DC converters
Pick one with a power rating that suits your needs.

They're not exactly a chip, but the small ones are small PCB mounting
components. There's lots of manufacturers out there making and selling them.

Anahata

On Tue, 13 Sep 2005 13:48:06 +0100, in rec.audio.pro Anahata
wrote:

H wrote:
Can anyone recommend a chip to convert 24V DC to 48V DC? Someone told
they exist and that the output current would be half the input current
in order to double the output voltage. I'm bulding a phantom power supply.

Google for DC-DC converters
Pick one with a power rating that suits your needs.

They're not exactly a chip, but the small ones are small PCB mounting
components. There's lots of manufacturers out there making and selling them.

Anahata
But beware, look at the output ripple of the converter, it will often
be 10 times the amplitude of the mic signal. Make sure that the
operating frequency is not close to a digital converters' clock
harmonic
LT1533 is a quiet device, but You Must Read AN70 fromLinear devices


martin

H wrote:
Can anyone recommend a chip to convert 24V DC to 48V DC? Someone told
they exist and that the output current would be half the input current
in order to double the output voltage. I'm bulding a phantom power supply.

It's not a single chip, it's going to be a hybrid module. Do a google
search on "48V dc-dc converter" and you'll find a bunch of them. It is
usually cheaper just to add an additional winding to the transformer to
get 48V, or use a voltage multiplier, though. If you're stuck with battery
power, though, the DC-DC converter is the way to go but be very careful
of noise issues.
---scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

martin griffith wrote:

But beware, look at the output ripple of the converter, it will often
be 10 times the amplitude of the mic signal.

I know, I was only responding rather literally to what the OP was asking
for. I'm amazed that DC-DC converter tech is so popular in mic preamps,
being an obvious source of noise. Regulation may be an issue with these
hybrid devices too, unless you get an expensive one with linear
regulation included.

If I was designing a mic pre I'd take the P48 off a voltage multiplier
from the main power supply (as suggested in another reply) and linearly
regulate down to a nice low noise 48V. I'd also be able to ramp the 48V
up and down slowly that way, common practice and kinder to electronics,
speakers and ears.

Anahata

H wrote:

Can anyone recommend a chip to convert 24V DC to 48V DC? Someone told
they exist and that the output current would be half the input current
in order to double the output voltage. I'm bulding a phantom power supply.

It's not a 'chip' !

Too many ppl today seem to think there a 'chip' to do everything.

You can get a module to do this but it may be too electrically noisy - EMI etc
- than you would like..

Graham

"H" wrote ...
Can anyone recommend a chip to convert 24V DC to 48V DC? Someone told
they exist and that the output current would be half the input current
in order to double the output voltage. I'm bulding a phantom power
supply.

How do you happen to have 24V DC?
Do you have access to 24V AC (perhaps at the other side
of the rectifier/filter)? Many pieces of equipment that are
highly regarded in this neighborhood use voltage doubler
circuits to create the P48 power because of the very modest
current requirements.

DC-to-DC converters are to be avoided for many reasons
unless there is really no alternative. There is no single-
"chip" solution to voltage conversion at this time.

"Richard Crowley" wrote in message

"H" wrote ...
Can anyone recommend a chip to convert 24V DC to 48V DC?
Someone told they exist and that the output current
would be half the input current in order to double the
output voltage. I'm bulding a phantom power supply.

How do you happen to have 24V DC?
Do you have access to 24V AC (perhaps at the other side
of the rectifier/filter)? Many pieces of equipment that
are highly regarded in this neighborhood use voltage
doubler circuits to create the P48 power because of the
very modest current requirements.

DC-to-DC converters are to be avoided for many reasons
unless there is really no alternative. There is no single-
"chip" solution to voltage conversion at this time.

Depends on how strictly you define "single chip"

The Maxim catalog has a ton of DC-DC chips. Most if not all
require outboard parts. AFAK none are designed for this
particular application. The required output voltage is on
the high side.

"Arny Krueger" wrote in message
...
"Richard Crowley" wrote in message

"H" wrote ...
Can anyone recommend a chip to convert 24V DC to 48V DC?
Someone told they exist and that the output current
would be half the input current in order to double the
output voltage. I'm bulding a phantom power supply.

How do you happen to have 24V DC?
Do you have access to 24V AC (perhaps at the other side
of the rectifier/filter)? Many pieces of equipment that
are highly regarded in this neighborhood use voltage
doubler circuits to create the P48 power because of the
very modest current requirements.

DC-to-DC converters are to be avoided for many reasons
unless there is really no alternative. There is no single-
"chip" solution to voltage conversion at this time.

Depends on how strictly you define "single chip"

The Maxim catalog has a ton of DC-DC chips. Most if not all require
outboard parts. AFAK none are designed for this particular
application. The required output voltage is on the high side.

Most require inductors (the rest use capacitors). They
are not particularly easy/convienent for casual users.
None of them accomplish the conversion completely
within the chip package. The power requirements all
demand larger, exernal components. The difficulty
of using these chips is decreasing, but there is still a
good market for pre-engineered sub-systems.

Richard Crowley wrote:

"Arny Krueger" wrote in message
...

"Richard Crowley" wrote in message


"H" wrote ...

Can anyone recommend a chip to convert 24V DC to 48V DC?
Someone told they exist and that the output current
would be half the input current in order to double the
output voltage. I'm bulding a phantom power supply.


How do you happen to have 24V DC?
Do you have access to 24V AC (perhaps at the other side
of the rectifier/filter)? Many pieces of equipment that
are highly regarded in this neighborhood use voltage
doubler circuits to create the P48 power because of the
very modest current requirements.

DC-to-DC converters are to be avoided for many reasons
unless there is really no alternative. There is no single-
"chip" solution to voltage conversion at this time.


Depends on how strictly you define "single chip"

The Maxim catalog has a ton of DC-DC chips. Most if not all require
outboard parts. AFAK none are designed for this particular
application. The required output voltage is on the high side.


Most require inductors (the rest use capacitors). They
are not particularly easy/convienent for casual users.
None of them accomplish the conversion completely
within the chip package. The power requirements all
demand larger, exernal components. The difficulty
of using these chips is decreasing, but there is still a
good market for pre-engineered sub-systems.



Check out the PTI products (now from TI) with integrated inductor. Far
too noisy for this app, though.

"H" wrote in message
news:YlzVe.168745$wr.73319@clgrps12...
Can anyone recommend a chip to convert 24V DC to 48V DC? Someone told
they exist and that the output current would be half the input current
in order to double the output voltage. I'm bulding a phantom power
supply.

Well, you can build a circuit to do that - you'll need an electronics
cookbook. I think they are called "level shifters". I think you'll need to
cascade a few chips - using the output of one to power the next - to end up
with a range of 48V.

However, do you actually need 48V? If you're providing phantom power for
microphones, you'll likely find yours work perfectly well with 24V.

Tim

Tim Martin wrote:
Well, you can build a circuit to do that - you'll need an electronics
cookbook. I think they are called "level shifters".

More commonly known as "DC to DC converters", in my experience. Voltage
doubling should be possible. You'll get less than half the amps out due
to inefficiencies in the process.

I'd second Tim's suggestion of first seeing if you can get away with 24V.

Another solution, of course, is to swap out the power supply for one
that produces both 24V and 48V, making it Someone Else's Problem.

My mixer currently uses 5 9V batteries for phantom. Inside the boards
power supply, there is a multi-tap transformer with 2 of it's wires
disconnected from the main board. I read 36 VAC from this but it
flickers to 0 sometimes so there could be an internal short and that's
why it was disconnected.

Building my own supply seems like the way to go. I think I will use this
design:


http://members.aol.com/ecc81/ps48.html

look good?



Mike Rivers wrote:
H wrote:

Can anyone recommend a chip to convert 24V DC to 48V DC? Someone told
they exist and that the output current would be half the input current
in order to double the output voltage. I'm bulding a phantom power supply.


I don't think that anyone makes a chip like this yet, but there are
some chips that are the guts of a DC-DC converter (which is what you
have to build) that are designed to use with a transformer and some
external components.

You might want to read this document and the "charge pump" application
note from the same web site:
http://www.maxim-ic.com/appnotes.cfm...te_number/2031

Unless this is for a portable (battery powered) application, you'll get
where you want to be a whole lot sooner if you just buy a commercial
phantom power supply or build one using a transformer and rectifier. Or
make/buy a battery phantom power supply. Five 9V batteries in series
will power most mics for a day or so (but test it before you go too far
from a 7-11).

"H" wrote in message
...

Building my own supply seems like the way to go. I think I will use this
design:


http://members.aol.com/ecc81/ps48.html

look good?

Can't see a diagram. Here's another design, anyway:

http://sound.westhost.com/project96.htm

Tim

"H" wrote in message

My mixer currently uses 5 9V batteries for phantom.
Inside the boards power supply, there is a multi-tap
transformer with 2 of it's wires disconnected from the
main board. I read 36 VAC from this but it flickers to 0
sometimes so there could be an internal short and that's
why it was disconnected.
Building my own supply seems like the way to go. I think
I will use this design:


http://members.aol.com/ecc81/ps48.html

look good?


Looks like much of the contents of my Audio Technica Phantom
supply.

H wrote:

My mixer currently uses 5 9V batteries for phantom. Inside the boards
power supply, there is a multi-tap transformer with 2 of it's wires
disconnected from the main board. I read 36 VAC from this but it
flickers to 0 sometimes so there could be an internal short and that's
why it was disconnected.

Building my own supply seems like the way to go. I think I will use this
design:

http://members.aol.com/ecc81/ps48.html

look good?

It looks fine.

There's a cute way to reduce ripple at the output further that they've missed but
I don't expect it'll be of any consequence.

Graham