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Need a regulator or step-down circuit that steps a battery down from 7.2v to 4.7v

I

IdeaMan

Jan 1, 1970
0
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 [email protected] of [email protected] .
 
R

Randy Day

Jan 1, 1970
0
IdeaMan said:
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
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
 
R

Rene Tschaggelar

Jan 1, 1970
0
IdeaMan said:
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 [email protected] of [email protected] .

You come here to read the answer...

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

Rene
 
A

amdx

Jan 1, 1970
0
The diode circuit as drawn will only have about 2.1 volts output.
 
K

Ken Moffett

Jan 1, 1970
0
amdx said:
The diode circuit as drawn will only have about 2.1 volts output.

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.
 
M

Mjolinor

Jan 1, 1970
0
Randy Day said:
DOH!!!

What was I thinking?

I suggest you were probably thinking " why did I drink so much beer last
night" or similar.
 
T

Tam/WB2TT

Jan 1, 1970
0
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
[email protected] .
 
K

Ken Moffett

Jan 1, 1970
0
Tam/WB2TT said:
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

[email protected] .

Very true!
 
J

Jamie

Jan 1, 1970
0
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.
 
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