adapting 12vdc to 9vdc

On Sat, 21 Jan 2012 16:50:58 -0600, the renowned Jim Yanik
<jyanik@abuse.gov> wrote:

Kripton wrote in news:4f1afdb7$0$4206$426a74cc@news.free.fr:

On 2012-01-21 18:55:59 +0100, greenpjs@neo.rr.com said:

On Sat, 21 Jan 2012 05:27:16 -0800, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:

No one mentioned putting a string of silicon diodes in series to lower
the voltage. Unlike a resistor, the voltage drop would be reasonable
fixed. But, no fancy parts, capacitors, etc are required. Sort of
crude, but why wouldn't it work? 7 diodes would drop approx 4.2 volts
bringing 13ish down to 9ish. Or, maybe 8 diodes to be safe. 13.8 down
to 9. Just wondering why no one mentioned the possibility. Heat
would have to be handled, but no worse than a three terminal regulator
and the heat would be spread across all 8 diodes.

Excellent idea. 1N400x rectifiers should work.

Exactly! I have a bunch of 1N4003's in my junk box that I used for
any project needing a general purpose diode that can handle some
power.

you mention it : the voltage of a car battery varies ...
from 14v to 12v or less
does the boom box handle 10v to 8v ? or not ?
that's why a regulator is needed, except if a regulation is made inside
the boom box ?
who knows...

you also need FILTERING to reduce ripple(and noise);
auto alternators do NOT output straight DC,but pulsating DC.

A regulator IC will reject a lot of ripple and noise.
a string of diodes will not.
Click to expand...
Actually, it makes it worse (percentage-wise).


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
PlainBill@yawhoo.com wrote:

On Thu, 19 Jan 2012 10:07:50 +0800, Rheilly Phoull
rheilly@bigslong.com> wrote:


On 1/19/2012 6:55 AM, Chas wrote:

I plan to use a ''boombox" in my vehicle because the existing sound device
is defective and next to impossible to remove.
My boombox uses 6 AA batteries...would it be safe to just run a plug from
the 12v cig lighter to a power plug on the boombox? I imagine I will need
some sort of voltage reducer. Anyone got any ideas on how one could build
such a reducer. I am fearing such a device may induce noise.
. . . . .I am of an understanding that 1.5v batterys are acutally 1.2v. Is
this correct? If so, I could run the 12v car voltage to 10 AA batterys and
then tap off six batterys....
Else, if the AA's are truly 1.5 volts then run the 12v car power to 8 of the
AA's and tap off 6.
any help would be greatly appreciated.. . . chas



Just search for "three terminal regulator" until you find a circuit for
the 9volt one. This is a very simple circuit and easy to build, I have
had such in use for years in my vehicles. You can build it in a small
diecast box which would be strong and act as a heat sink for the regulator.

Rheilly P

To expound on this idea, the xx1084 family of regulators would be
ideal. Specifically, the AP1084TL-U adjustable regulator. Datasheet:
http://www.diodes.com/datasheets/AP1084.pdf. It's capable of putting
out 5A and has thermal shutdown.

The parts list is simple - An AP1084TL-U, 2 ea 100ľF, 25volt caps, a
120 ohm and a 750 ohm 1/4 watt resistor, the die cast box, and an
insulator - the tab of the AP1084 is at the output voltage.

PlainBill
Click to expand...
How about jest a 5 volt zener diode in series and a a small capacitor
after it to filter out noise?

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10e12 furlongs per fortnight.
 
Chas wrote:
I plan to use a ''boombox" in my vehicle because the existing sound device
is defective and next to impossible to remove.
My boombox uses 6 AA batteries...would it be safe to just run a plug from
the 12v cig lighter to a power plug on the boombox? I imagine I will need
some sort of voltage reducer. Anyone got any ideas on how one could build
such a reducer. I am fearing such a device may induce noise.
. . . . .I am of an understanding that 1.5v batterys are acutally 1.2v. Is
this correct? If so, I could run the 12v car voltage to 10 AA batterys and
then tap off six batterys....
Else, if the AA's are truly 1.5 volts then run the 12v car power to 8 of the
AA's and tap off 6.
any help would be greatly appreciated.. . . chas
Click to expand...

http://www.ebay.com/itm/180763839264 is an adjustble 3A buck
regulator for less than $5. It's a switch mode power supply, so it won't
generate a lot of waste heat.


--
You can't have a sense of humor, if you have no sense.
 
On 2012-01-27 03:38:55 +0100, "Michael A. Terrell"
<mike.terrell@earthlink.net> said:

Chas wrote:

I plan to use a ''boombox" in my vehicle because the existing sound device
is defective and next to impossible to remove.
My boombox uses 6 AA batteries...would it be safe to just run a plug from
the 12v cig lighter to a power plug on the boombox? I imagine I will need
some sort of voltage reducer. Anyone got any ideas on how one could build
such a reducer. I am fearing such a device may induce noise.
. . . . .I am of an understanding that 1.5v batterys are acutally 1.2v. Is
this correct? If so, I could run the 12v car voltage to 10 AA batterys and
then tap off six batterys....
Else, if the AA's are truly 1.5 volts then run the 12v car power to 8 of the
AA's and tap off 6.
any help would be greatly appreciated.. . . chas


http://www.ebay.com/itm/180763839264 is an adjustble 3A buck
regulator for less than $5. It's a switch mode power supply, so it won't
generate a lot of waste heat.
Click to expand...
and more searching on ebay for "LM2596" gives you the same board for
$2.5 shipped ...
and agree it does not generate waste heat !
but they don't seems to search for a smart solution...
--
----------
Kripton

the ESR Repository @ http://kripton2035.free.fr/esr-repository.html
the Geiger Repository @ http://kripton2035.free.fr/geiger-repositor.html
 
Kripton wrote:
On 2012-01-27 03:38:55 +0100, "Michael A. Terrell"
mike.terrell@earthlink.net> said:


Chas wrote:

I plan to use a ''boombox" in my vehicle because the existing sound device
is defective and next to impossible to remove.
My boombox uses 6 AA batteries...would it be safe to just run a plug from
the 12v cig lighter to a power plug on the boombox? I imagine I will need
some sort of voltage reducer. Anyone got any ideas on how one could build
such a reducer. I am fearing such a device may induce noise.
. . . . .I am of an understanding that 1.5v batterys are acutally 1.2v. Is
this correct? If so, I could run the 12v car voltage to 10 AA batterys and
then tap off six batterys....
Else, if the AA's are truly 1.5 volts then run the 12v car power to 8 of the
AA's and tap off 6.
any help would be greatly appreciated.. . . chas


http://www.ebay.com/itm/180763839264 is an adjustble 3A buck
regulator for less than $5. It's a switch mode power supply, so it won't
generate a lot of waste heat.

and more searching on ebay for "LM2596" gives you the same board for
$2.5 shipped ...
and agree it does not generate waste heat !
but they don't seems to search for a smart solution...
Click to expand...

Whatever. A simple, adjustable switcher that doen't need any design
work to use is a good idea for people who aren't equipped to design a
power supply from scratch.

--
You can't have a sense of humor, if you have no sense.
 
On 1/28/2012 3:02 AM, Michael A. Terrell wrote:
Kripton wrote:

On 2012-01-27 03:38:55 +0100, "Michael A. Terrell"
mike.terrell@earthlink.net> said:


Chas wrote:

I plan to use a ''boombox" in my vehicle because the existing sound device
is defective and next to impossible to remove.
My boombox uses 6 AA batteries...would it be safe to just run a plug from
the 12v cig lighter to a power plug on the boombox? I imagine I will need
some sort of voltage reducer. Anyone got any ideas on how one could build
such a reducer. I am fearing such a device may induce noise.
. . . . .I am of an understanding that 1.5v batterys are acutally 1.2v. Is
this correct? If so, I could run the 12v car voltage to 10 AA batterys and
then tap off six batterys....
Else, if the AA's are truly 1.5 volts then run the 12v car power to 8 of the
AA's and tap off 6.
any help would be greatly appreciated.. . . chas


http://www.ebay.com/itm/180763839264 is an adjustble 3A buck
regulator for less than $5. It's a switch mode power supply, so it won't
generate a lot of waste heat.

and more searching on ebay for "LM2596" gives you the same board for
$2.5 shipped ...
and agree it does not generate waste heat !
but they don't seems to search for a smart solution...


Whatever. A simple, adjustable switcher that doen't need any design
work to use is a good idea for people who aren't equipped to design a
power supply from scratch.

And those who think they can't etch a circuit board, order the parts from
Click to expand...
Digikey at single unit prices plus shipping, build/test it for
less than $2.50.

Just because you can, doesn't mean you should.
 
mike wrote:
On 1/28/2012 3:02 AM, Michael A. Terrell wrote:

Kripton wrote:

On 2012-01-27 03:38:55 +0100, "Michael A. Terrell"
mike.terrell@earthlink.net> said:


Chas wrote:

I plan to use a ''boombox" in my vehicle because the existing sound device
is defective and next to impossible to remove.
My boombox uses 6 AA batteries...would it be safe to just run a plug from
the 12v cig lighter to a power plug on the boombox? I imagine I will need
some sort of voltage reducer. Anyone got any ideas on how one could build
such a reducer. I am fearing such a device may induce noise.
. . . . .I am of an understanding that 1.5v batterys are acutally 1.2v. Is
this correct? If so, I could run the 12v car voltage to 10 AA batterys and
then tap off six batterys....
Else, if the AA's are truly 1.5 volts then run the 12v car power to 8 of the
AA's and tap off 6.
any help would be greatly appreciated.. . . chas


http://www.ebay.com/itm/180763839264 is an adjustble 3A buck
regulator for less than $5. It's a switch mode power supply, so it won't
generate a lot of waste heat.

and more searching on ebay for "LM2596" gives you the same board for
$2.5 shipped ...
and agree it does not generate waste heat !
but they don't seems to search for a smart solution...


Whatever. A simple, adjustable switcher that doen't need any design
work to use is a good idea for people who aren't equipped to design a
power supply from scratch.

And those who think they can't etch a circuit board, order the parts from
Digikey at single unit prices plus shipping, build/test it for
less than $2.50.

Just because you can, doesn't mean you should.
Click to expand...

Unless you plan on building a lot of them. I've worked in electronics
manufacturing, and it's not as simple as most people think. We had
three reflow ovens, a preheat cabinet and a 10 * 40 foot room where
boards were cleaned. First, in a commercial board washer, then
inspected and cleaned by hand, if needed. Most components don't go
cheap, if you buy under 1000 at a time. Some at 5,000 and others at
50,000.


--
You can't have a sense of humor, if you have no sense.
 
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