Re: 12 V -> 3V, 0.6 A

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Article #11316

#11316

From: Babak Sehari
Date: Mon, 09 Nov 1992 03:42

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In <1992Nov7.141550.538@ludd.luth.se> d89-ahg@ludd.luth.se (Anders Hedberg) writes:

>A friend wants to listen to his CD player powered from the car.

>The CD-player wanna have 3Volts at max 600 mA, and the car has a battery
>of 12 volts.

>I thought of a LM317 or something similar, but I've never designed something
>alike, and I need to know how to calculate the resistor values.

>/Anders Hedberg

There are many ways to do this the cheapest way is to put:

  12-3
--------- = 13 diodes in series with the input voltage of your CD player,
    0.7

Like this:

+12V -|>|-|>|-|>|-|>|-|>|-|>|-|>|-|>|-|>|-|>|-|>|-|>|- +3V
GRD  --------------------------------------------------

The problem might be generated if the input voltage swings.  To avoid
this problem try putting a 2N3055 transistor as follows:

+12V |>|-|>|-|>|-|>|-|>|-|>|-|>|-|>|-|>|-    ---+3V
                                        | \_/ Emitter
                                        R  |
                                        |--|
                                        |
                                        ||>|-|>|-|>|-|>|-|>|-|
                                                             |
GRD ---------------------------------------------------------+-----
                                    

R=1000 ohm
Trans=2n3055
Diodes= 1N4001 or 1N4005

                         With highest regards,
                              Babak   Sehari.
--

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From: sehari@iastate.edu (Babak Sehari)
Newsgroups: sci.electronics
Subject: Re: 12 V -> 3V, 0.6 A
Message-ID: <sehari.721280522@class1.iastate.edu>
Date: 9 Nov 92 03:42:02 GMT
References: <1992Nov7.141550.538@ludd.luth.se>
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