adapting 12vdc to 9vdc

On Wed, 18 Jan 2012 15:55:09 -0700, the renowned "Chas"
<footboarder@bresnan.net> 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...
Hey, this little device would probably have adequate capacity ;-)

http://www.nextag.com/Medela-9-Volt-Vehicle-595671550/prices-html?nxtg=4bf80a280508-548F46D24A00A4FA



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
 
Hey, this little device would probably have adequate capacity. ;-)

http://www.nextag.com/Medela-9-Volt-Vehicle-595671550/prices-html?nxtg=4bf80a280508-548F46D24A00A4FA
Click to expand...

The question is... what is the original poster's "capacity"? <ahem>
 
On 2012-01-19, Kripton <Kripton> wrote:
that means the energy if transformed into heat, useless and poor solution
for the planet ...
Click to expand...
BARF! I for will not lift a finger to "save the planet." It doesn't need
saving, and if it did "reducing power losses" is not going to do the trick.

--
-----------------------------------------------------------------------------
Roger Blake (Change "invalid" to "com" for email. Google Groups killfiled.)

"Climate policy has almost nothing to do anymore with environmental
protection... the next world climate summit in Cancun is actually
an economy summit during which the distribution of the world's
resources will be negotiated." -- Ottmar Edenhofer, IPCC
-----------------------------------------------------------------------------
 
On Jan 19, 6:49 pm, Roger Blake <rogbl...@iname.invalid> wrote:
On 2012-01-19, Kripton <Kripton> wrote:

that means the energy if transformed into heat, useless and poor solution
for the planet ...

BARF!  I for will not lift a finger to "save the planet." It doesn't need
saving, and if it did "reducing power losses" is not going to do the trick.

--
-----------------------------------------------------------------------------
  Roger Blake (Change "invalid" to "com" for email. Google Groups killfiled.)

  "Climate policy has almost nothing to do anymore with environmental
   protection... the next world climate summit in Cancun is actually
   an economy summit during which the distribution of the world's
   resources will be negotiated." -- Ottmar Edenhofer, IPCC
-----------------------------------------------------------------------------
Click to expand...
dimwit's .sig retained to show dimwittedness.

too bad he'll never know how fucked up his word wrap is.
 
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
Click to expand...
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
 
On Jan 20, 2:26 pm, PlainB...@yawhoo.com wrote:
On Thu, 19 Jan 2012 10:07:50 +0800, Rheilly Phoull









rhei...@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.
Click to expand...
One problem with using this part is the risk of destroying it as soon
as you start the car: The absolute maximum supply voltage is only 12V,
and the alternator puts out more than 13VDC.
 
"Chas" <footboarder@bresnan.net> 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
Click to expand...

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...
This all reminds me of my boom box I built in the early 80s. I used car
parts and a gel cell, compatible with car charging systems, which can reach
16 volts. Picture does not show horn loaded drivers.
http://www.zekfrivolous.com/slidesandstuff/slides1/PICT0055.JPG

Greg
 
On 1/21/2012 6:41 AM, spamtrap1888 wrote:
On Jan 20, 2:26 pm, PlainB...@yawhoo.com wrote:
On Thu, 19 Jan 2012 10:07:50 +0800, Rheilly Phoull









rhei...@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.


One problem with using this part is the risk of destroying it as soon
as you start the car: The absolute maximum supply voltage is only 12V,
and the alternator puts out more than 13VDC.

The 7809 has a max input of 40v from memory.
Click to expand...

Rheilly P
 
On Jan 21, 1:04 am, Rheilly Phoull <rhei...@bigslong.com> wrote:
On 1/21/2012 6:41 AM, spamtrap1888 wrote:







On Jan 20, 2:26 pm, PlainB...@yawhoo.com wrote:
On Thu, 19 Jan 2012 10:07:50 +0800, Rheilly Phoull

rhei...@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.

One problem with using this part is the risk of destroying it as soon
as you start the car: The absolute maximum supply voltage is only 12V,
and the alternator puts out more than 13VDC.

The 7809 has a max input of 40v from memory.
Click to expand...
I'd use a 7809 myself, but the part with the low abs max Vin
recommended here was a AP1084TL-U.
 
On 1/21/2012 5:48 PM, spamtrap1888 wrote:
On Jan 21, 1:04 am, Rheilly Phoull<rhei...@bigslong.com> wrote:
On 1/21/2012 6:41 AM, spamtrap1888 wrote:







On Jan 20, 2:26 pm, PlainB...@yawhoo.com wrote:
On Thu, 19 Jan 2012 10:07:50 +0800, Rheilly Phoull

rhei...@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.

One problem with using this part is the risk of destroying it as soon
as you start the car: The absolute maximum supply voltage is only 12V,
and the alternator puts out more than 13VDC.

The 7809 has a max input of 40v from memory.


I'd use a 7809 myself, but the part with the low abs max Vin
recommended here was a AP1084TL-U.
Click to expand...
I don't understand the problem. I have been using the 7809 etc. for
years in the automotive situation without a single failure.
It's not exactly rocket science :)

Rheilly P
 
I don't understand the problem. I have been using the 7809
etc. for years in the automotive situation without a single
failure. It's not exactly rocket science. :)
Click to expand...
The problem is that the OP probably knows little about electronics, and is
likely to completely botch the project. He'll return to us asking for
troubleshooting help.
 
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.
Click to expand...
Excellent idea. 1N400x rectifiers should work.
 
On Sat, 21 Jan 2012 01:48:39 -0800 (PST), spamtrap1888
<spamtrap1888@gmail.com> wrote:

On Jan 21, 1:04 am, Rheilly Phoull <rhei...@bigslong.com> wrote:
On 1/21/2012 6:41 AM, spamtrap1888 wrote:







On Jan 20, 2:26 pm, PlainB...@yawhoo.com wrote:
On Thu, 19 Jan 2012 10:07:50 +0800, Rheilly Phoull

rhei...@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.

One problem with using this part is the risk of destroying it as soon
as you start the car: The absolute maximum supply voltage is only 12V,
and the alternator puts out more than 13VDC.

The 7809 has a max input of 40v from memory.


I'd use a 7809 myself, but the part with the low abs max Vin
recommended here was a AP1084TL-U.
No one mentioned putting a string of silicon diodes in series to lower
Click to expand...
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.
 
On Jan 21, 8:27 am, "William Sommerwerck" <grizzledgee...@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.
Click to expand...
I tried running a small 9V transistor radio years ago at work from a
12V supply. I used a zener and a series resistor. Even with such a
small radio the pair got much too hot. The OP plans to power a boom
box. At the least he'll need to use a three terminal regulator or a
series pass transistor with the zener in the base circuit. Whatever it
turns out to be may need a heat sink, must be properly polarized,
fused, adequately wired, (so as to not set the vehicle on fire), and
I agree with William that this project, although simple to a seasoned
technician might be beyond his capabilities. Lenny
 
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
Click to expand...
any project needing a general purpose diode that can handle some
power.
 
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.
Click to expand...
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...
--
----------
Kripton

the ESR Repository @ http://kripton2035.free.fr/esr-repository.html
the Geiger Repository @ http://kripton2035.free.fr/geiger-repositor.html
 
On Sat, 21 Jan 2012 21:23:33 +0800, the renowned Rheilly Phoull
<rheilly@bigslong.com> wrote:


I don't understand the problem. I have been using the 7809 etc. for
years in the automotive situation without a single failure.
It's not exactly rocket science :)

Rheilly P
Click to expand...
It's not rocket science, but there are some subtleties:-

http://www.vishay.com/docs/88490/tvs.pdf

A few parts (series 1N400x, series power resistor, parallel TVS) will
protect the regulator against +/-100V transients and reverse wiring.


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
 
forward voltage drop of a diode varies with current through the diode.
Click to expand...
"Yes, but..." It's much closer to being constant, than it is with a
resistor.
 
greenpjs@neo.rr.com wrote in
news:e9flh7564fg8t2iflevfr6umo72tbt9hnc@4ax.com:

On Sat, 21 Jan 2012 01:48:39 -0800 (PST), spamtrap1888
spamtrap1888@gmail.com> wrote:

On Jan 21, 1:04 am, Rheilly Phoull <rhei...@bigslong.com> wrote:
On 1/21/2012 6:41 AM, spamtrap1888 wrote:







On Jan 20, 2:26 pm, PlainB...@yawhoo.com wrote:
On Thu, 19 Jan 2012 10:07:50 +0800, Rheilly Phoull

rhei...@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.

One problem with using this part is the risk of destroying it as
soon as you start the car: The absolute maximum supply voltage is
only 12V, and the alternator puts out more than 13VDC.

The 7809 has a max input of 40v from memory.


I'd use a 7809 myself, but the part with the low abs max Vin
recommended here was a AP1084TL-U.
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.
Click to expand...
forward voltage drop of a diode varies with current through the diode.

--
Jim Yanik
jyanik
at
localnet
dot com
 
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...
Click to expand...
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.

but hey,it's your boom box.(and ears)


--
Jim Yanik
jyanik
at
localnet
dot com
 
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