Maker Pro
Maker Pro

Adjustable amplifier rails.

M

Michael

Jan 1, 1970
0
I have an idea, but i'm not an expert on switchmode power supplies so
I'd like to run it past you guys.

I wish to make a portable high powered stereo for camping trips using
a car audio amplifier (2x60W), a lead acid battery and either a car
head unit or cd walkman.
These amplifiers use a switchmode supply which generates approx +/-
30V rails.

I was thinking, I could have adjustable rails, with a slow decay (say
3-4V per min) and a fast attack which would be triggered by a clipping
sensor on the amp.
This would increase the battery life at lower listening levels, where
30V of headroom would waste a lot of power.

Would there be a problem with dropping voltage when the transformer
is wound to create 30V rails, providing the PWM circuit can generate
short enough pulses?




Michael.......
 
J

John Larkin

Jan 1, 1970
0
I have an idea, but i'm not an expert on switchmode power supplies so
I'd like to run it past you guys.

I wish to make a portable high powered stereo for camping trips using
a car audio amplifier (2x60W), a lead acid battery and either a car
head unit or cd walkman.

Geez, just what Yosemite needs.

John
 
K

Kevin McMurtrie

Jan 1, 1970
0
I have an idea, but i'm not an expert on switchmode power supplies so
I'd like to run it past you guys.

I wish to make a portable high powered stereo for camping trips using
a car audio amplifier (2x60W), a lead acid battery and either a car
head unit or cd walkman.
These amplifiers use a switchmode supply which generates approx +/-
30V rails.

I was thinking, I could have adjustable rails, with a slow decay (say
3-4V per min) and a fast attack which would be triggered by a clipping
sensor on the amp.
This would increase the battery life at lower listening levels, where
30V of headroom would waste a lot of power.

Would there be a problem with dropping voltage when the transformer
is wound to create 30V rails, providing the PWM circuit can generate
short enough pulses?




Michael.......

The switching power supply in most car audio amps isn't variable by
much, if at all. Consider one of the Class D variations for efficient
power.
 
D

DaveC

Jan 1, 1970
0
On 20 Nov 2003 15:41:44 -0800, [email protected] (Michael) wrote:
Geez, just what Yosemite needs.

LOL... I thought I was the only one in the campground who longed to hear
*only* the crickets and the surf...

Leave the damn stereo at home!!!

There. How I've longed to yell that from my tent.
 
R

Rene Tschaggelar

Jan 1, 1970
0
Michael said:
I have an idea, but i'm not an expert on switchmode power supplies so
I'd like to run it past you guys.

I wish to make a portable high powered stereo for camping trips using
a car audio amplifier (2x60W), a lead acid battery and either a car
head unit or cd walkman.
These amplifiers use a switchmode supply which generates approx +/-
30V rails.

I was thinking, I could have adjustable rails, with a slow decay (say
3-4V per min) and a fast attack which would be triggered by a clipping
sensor on the amp.
This would increase the battery life at lower listening levels, where
30V of headroom would waste a lot of power.

Would there be a problem with dropping voltage when the transformer
is wound to create 30V rails, providing the PWM circuit can generate
short enough pulses?

A switchmode amplifier doesn't waste power with higher rails,
or not much anyway.
As the others said, it is an almost infinitely bad idea to
take the stereo for camping. Stay in the city and cut the lawn.
Brrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr...

Rene
 
R

Ralph & Diane Barone

Jan 1, 1970
0
I have an idea, but i'm not an expert on switchmode power supplies so
I'd like to run it past you guys.

I wish to make a portable high powered stereo for camping trips using
a car audio amplifier (2x60W), a lead acid battery and either a car
head unit or cd walkman.
These amplifiers use a switchmode supply which generates approx +/-
30V rails.

I was thinking, I could have adjustable rails, with a slow decay (say
3-4V per min) and a fast attack which would be triggered by a clipping
sensor on the amp.
This would increase the battery life at lower listening levels, where
30V of headroom would waste a lot of power.

Would there be a problem with dropping voltage when the transformer
is wound to create 30V rails, providing the PWM circuit can generate
short enough pulses?




Michael.......

Why not just cheat and add another ganged element to the volume pot. Use
the position of the volume pot to set the power supply voltage reference.
Judiciously set up, this should get you 99% of the way there.
 
M

Mike Page

Jan 1, 1970
0
Michael said:
I have an idea, but i'm not an expert on switchmode power supplies so
I'd like to run it past you guys.

This would increase the battery life at lower listening levels, where
30V of headroom would waste a lot of power.

Michael.......

Buy a big enough solar panel and you won't have to worry too much about
battery life. That is, if the weather in Oz holds up ;-)
 
N

N. Thornton

Jan 1, 1970
0
Hi. Certainly this would significantly improve the efficiency of the
class B amp. If you use a class D amp instead you get even higher
efficiency.


Regards, NT
 
L

Linear

Jan 1, 1970
0
......
I was thinking, I could have adjustable rails, with a slow decay (say
3-4V per min) and a fast attack which would be triggered by a clipping
sensor on the amp.
This would increase the battery life at lower listening levels, where
30V of headroom would waste a lot of power.
.....
Take a look at the AD8393 on the Analog Devices Web site analog.com.

It functions like you describe, but at lower voltages.
 
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