Need a regulator or step-down circuit that steps a battery d

I

IdeaMan

Guest
I want to step down a 7.2v lithium ion (Li-ion) camcorder battery to 4.7v to power my digital camera for long periods of
time, can someone send me schematic via email or post one that fits my needs. Thank you for help with this. I forgot the
email address: please send to blowphish@juno.com of hypnotech@juno.com .
 
IdeaMan wrote:
I want to step down a 7.2v lithium ion (Li-ion) camcorder battery to 4.7v to power my digital camera for long periods of
time, can someone send me schematic via email or post one that fits my needs. Thank you for help with this.
Simple and cheap; since you don't indicate a peak
Click to expand...
current requirement, you'll have to calculate a
value for R.

Any 3 diodes capable of handling the max expected
current will work; yes, the diode polarity is
correct as drawn.


R
___
7.2v in-|___|-+-----o ~4.5v out
|
V D1
-
|
|
V D2
-
|
|
V D3
-
|
GND


created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

I forgot the
email address: please send to blowphish@juno.com of hypnotech@juno.com .
Click to expand...
 
IdeaMan wrote:

I want to step down a 7.2v lithium ion (Li-ion) camcorder battery to 4.7v to power my digital camera for long periods of
time, can someone send me schematic via email or post one that fits my needs. Thank you for help with this. I forgot the
email address: please send to blowphish@juno.com of hypnotech@juno.com .
Click to expand...
You come here to read the answer...

There are tons of switchers available from various manufacturers.
texasinstruments, lineartech, ...

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
 
The diode circuit as drawn will only have about 2.1 volts output.

Any 3 diodes capable of handling the max expected
current will work; yes, the diode polarity is
correct as drawn.


R
___
7.2v in-|___|-+-----o ~4.5v out
|
V D1
-
|
|
V D2
-
|
|
V D3
-
|
GND


created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

I forgot the
email address: please send to blowphish@juno.com of hypnotech@juno.com .
Click to expand...
 
amdx wrote:
The diode circuit as drawn will only have about 2.1 volts output.

Any 3 diodes capable of handling the max expected
current will work; yes, the diode polarity is
correct as drawn.


R
___
7.2v in-|___|-+-----o ~4.5v out
|
V D1
-
|
|
V D2
-
|
|
V D3
-
|
GND


created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

I forgot the
email address: please send to blowphish@juno.com of hypnotech@juno.com .
Click to expand...
Why go to a shunt regulator? It wastes current in the diode string
paralleling your load. A "series" diode regulator will only see the
load current:

Gnd---+7.2v--->|--->|--->|--->|---+4.7---Gnd

This could be a mixture of standard silicon diodes and schottky diodes
(with appropriate current and power ratings) to get the right voltage
drop.
 
"Randy Day" <ruthal@sasktel.nex> wrote in message
news:40939D42.61EC95C6@sasktel.nex...
amdx wrote:

The diode circuit as drawn will only have about 2.1 volts output.

DOH!!!

What was I thinking?
Click to expand...
I suggest you were probably thinking " why did I drink so much beer last
night" or similar.
 
I would put a light load of a couple of ma on the output of the diodes, so
you don't hit the camera with 7.2V when you connect it. If you want to do it
right, use an adjustable linear regulator.

Tam
"Ken Moffett" <KLMoffett@mn.rr.com> wrote in message
news:40939BE7.27FE@mn.rr.com...
amdx wrote:

The diode circuit as drawn will only have about 2.1 volts output.

Any 3 diodes capable of handling the max expected
current will work; yes, the diode polarity is
correct as drawn.


R
___
7.2v in-|___|-+-----o ~4.5v out
|
V D1
-
|
|
V D2
-
|
|
V D3
-
|
GND


created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

I forgot the
email address: please send to blowphish@juno.com of
hypnotech@juno.com .

Why go to a shunt regulator? It wastes current in the diode string
paralleling your load. A "series" diode regulator will only see the
load current:

Gnd---+7.2v--->|--->|--->|--->|---+4.7---Gnd

This could be a mixture of standard silicon diodes and schottky diodes
(with appropriate current and power ratings) to get the right voltage
drop.
Click to expand...
 
Tam/WB2TT wrote:
I would put a light load of a couple of ma on the output of the diodes, so
you don't hit the camera with 7.2V when you connect it. If you want to do it
right, use an adjustable linear regulator.

Tam
"Ken Moffett" <KLMoffett@mn.rr.com> wrote in message
news:40939BE7.27FE@mn.rr.com..
amdx wrote:

The diode circuit as drawn will only have about 2.1 volts output.

Any 3 diodes capable of handling the max expected
current will work; yes, the diode polarity is
correct as drawn.


R
___
7.2v in-|___|-+-----o ~4.5v out
|
V D1
-
|
|
V D2
-
|
|
V D3
-
|
GND


created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

I forgot the
email address: please send to blowphish@juno.com of
hypnotech@juno.com .

Why go to a shunt regulator? It wastes current in the diode string
paralleling your load. A "series" diode regulator will only see the
load current:

Gnd---+7.2v--->|--->|--->|--->|---+4.7---Gnd

This could be a mixture of standard silicon diodes and schottky diodes
(with appropriate current and power ratings) to get the right voltage
drop.
Click to expand...
Very true!
 
"Roger Gt" <not@here.net> wrote in message news:...
:
: "IdeaMan" <??????@juno.com> wrote in message
: news:eek:aj690teksccja96kc6sggi4lefm8bq2tg@4ax.com...
: : I want to step down a 7.2v lithium ion (Li-ion) camcorder
: battery to 4.7v to power my digital camera for long periods of
: : time, can someone send me schematic via email or post one that
: fits my needs. Thank you for help with this. I forgot the
: : email address: please send to blowphish@juno.com of
: hypnotech@juno.com .
:
:
: Try this. National is so kind as to provide these simple
: designs....
:
: I chose to use a format for 2,3, or 4 of the 7.2 volt batteries
in
: series.
: With 4 and at 90% efficiency you should get about 3-4 hours
: operation. Putting a string of 4 in parallel with the 4 with
: another 4 will double the time. Is that what you had in mind?
:
: You can only parallel the same number of batteries. So if you
: chose 2 or 3, you use the same number in a parallel string. You
: may use more than 2 strings of batteries too. But if there are
: different levels of charge there will be some current between
: batteries, to prevent that, use the 1N5819 diodes in series (1
: each string) to provide isolation.
:
: Roger Gt
: -
: "Engineering is the art of molding materials we do not wholly
: understand into shapes we cannot precisely analyze so as to
: withstand forces we cannot really predict in such a way that the
: community at large has no reason to suspect the extent of our
: ignorance."
:
:
 
A SCHEMATIC WAS Send to the EBS group, IT didn't make it yet!
"Roger Gt" <not@here.net> wrote in message
news:pNRkc.58817$kO4.13937@newssvr25.news.prodigy.com...
:
: "Roger Gt" <not@here.net> wrote in message news:...
: :
: : "IdeaMan" <??????@juno.com> wrote in message
: : news:eek:aj690teksccja96kc6sggi4lefm8bq2tg@4ax.com...
: : : I want to step down a 7.2v lithium ion (Li-ion) camcorder
: : battery to 4.7v to power my digital camera for long periods of
: : : time, can someone send me schematic via email or post one
that
: : fits my needs. Thank you for help with this. I forgot the
: : : email address: please send to blowphish@juno.com of
: : hypnotech@juno.com .
: :
: :
: : Try this. National is so kind as to provide these simple
: : designs....
: :
: : I chose to use a format for 2,3, or 4 of the 7.2 volt
batteries
: in
: : series.
: : With 4 and at 90% efficiency you should get about 3-4 hours
: : operation. Putting a string of 4 in parallel with the 4 with
: : another 4 will double the time. Is that what you had in
mind?
: :
: : You can only parallel the same number of batteries. So if you
: : chose 2 or 3, you use the same number in a parallel string.
You
: : may use more than 2 strings of batteries too. But if there
are
: : different levels of charge there will be some current between
: : batteries, to prevent that, use the 1N5819 diodes in series (1
: : each string) to provide isolation.
: :
: : Roger Gt
: : -
: : "Engineering is the art of molding materials we do not wholly
: : understand into shapes we cannot precisely analyze so as to
: : withstand forces we cannot really predict in such a way that
the
: : community at large has no reason to suspect the extent of our
: : ignorance."
: :
: :
:
:
 
use a standard Post 5 volt regulator with 1 silicon diode in series on
the output, this will give you a drop enough to put the final output to
aprox 4.6 volts.
P.S.
the anode side will be connected to the Post output and the cathode
would be your final out.. you may want to place a bypass cap at the
output on the Post reg and cathode side of the diode.



IdeaMan wrote:

I want to step down a 7.2v lithium ion (Li-ion) camcorder battery to 4.7v to power my digital camera for long periods of
time, can someone send me schematic via email or post one that fits my needs. Thank you for help with this. I forgot the
email address: please send to blowphish@juno.com of hypnotech@juno.com .
Click to expand...
 
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