# 12 Volts 3 Amps DC vs 12 Volts 6 Amps DC

Discussion in 'Electronic Basics' started by Jerome Jahnke, Sep 27, 2004.

1. ### Jerome JahnkeGuest

I am working on a project. And I have two elements which take power
from two different AC to DC power converters. In this case it is an
LCD Display and a DC to DC power converter for a small computer. The
display is expecting 12v 3A and the DC to DC converter is expecting
12v 6A.

I have been looking around I understand that the product of volts and
amps make wattage, which make sense on the computer side as wattage is
what we need to make all the perphial devices go. But I am confused on
a few things.

1) If I just split the connector from the AC to DC converter how would
that affect the DC to DC converter (would it still actually be getting
12v 6A?)

2) If I split it and put some kind of (as yet unknown circut) in front
of the LDC Monitor to somehow convert it to 12v3A would that affect
the DC to DC converter.

3) Finally if I split it and did not convert it would the 12v 6A
damage the LCD?

I don't know enough about electronics to phrase the question which is
why I am having a problem finding the answer (the search engines don't
seem to be helping.) Ideally I would like this device to run on both
wall power with the AC to DC converter as well as off of a car's 14
volt electrical system.

Any adivce here would be very helpufl.

Jer,

2. ### The little lost angelGuest

On 26 Sep 2004 21:40:30 -0700, (Jerome Jahnke)
wrote:

I'm very newbie at this, but this sounds similar to what I've done
before so here's my shot at it. Veterans please correct me so that I
can see if I learnt anything after all these time pPp
I think you only need to worry about the volts. The devices will
determine how many amperes they draw, just make sure your supply can
handle the total power needed.
I once did something like this, clobbered together an adapter for my
LCD after I misplaced the original AC->DC converter. Essentially I
took a normal wallplugged AC to 24V DC adapter and added a simple 12V
regulated circuit using a MOSFET and some caps. The design was
according to the diagram provided by the power regulation mosfet
manufacturer. It worked pretty ok except I think I needed to use
bigger caps or the circuit sometimes doesn't provide enough power
during mode switch. Though I got around it simply by switching on the
LCD after the system booted pPpp It's something you might want to
keep in mind if the screen goes blank after a mode switch from say
text 320x240 to 800x600.

For your case, I think you would just have to make the two bits
detachable so you can plug in either the AC/DC converter or the car's
14 (isn't it 24V?) system.

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