High current DC-DC converter

[[email protected]]

Hi there.

Firstly, let me begin by stating that my knowledge of electronics is
somewhat basic, so please dont be offended if I ask a seemingly silly
question.

I would like to know if such a beast as a high current (around 5A or
so) DC-DC (12v to 30v) converter exists, or if they are (relatively)
easy to make.

The basis of the question is my car stereo. Frankly, the amplifier in
it is little better than weak, unable to deliver a clear sound at
anything above low to mid volume, which is a bit of a problem when I am
driving down the motorway with the windows down.

My idea was to use an amplifier kit from an electronics chain-store
over here in Britain (Maplin for anyone who is interested) and run this
from the line-level output from my car stereo. However, this is where
the problem shows up - the amp requires 30v or so, and as you are
no-doubt aware, a car battery only manages 12 volts.

So, any suggestions?

Thanks in advance for any help,

Roger Melly.
--
conckersack
at
yahoo
dot
com

 

[GregS]

Hi there.

Firstly, let me begin by stating that my knowledge of electronics is
somewhat basic, so please dont be offended if I ask a seemingly silly
question.

I would like to know if such a beast as a high current (around 5A or
so) DC-DC (12v to 30v) converter exists, or if they are (relatively)
easy to make.

The basis of the question is my car stereo. Frankly, the amplifier in
it is little better than weak, unable to deliver a clear sound at
anything above low to mid volume, which is a bit of a problem when I am
driving down the motorway with the windows down.

My idea was to use an amplifier kit from an electronics chain-store
over here in Britain (Maplin for anyone who is interested) and run this
from the line-level output from my car stereo. However, this is where
the problem shows up - the amp requires 30v or so, and as you are
no-doubt aware, a car battery only manages 12 volts.

So, any suggestions?

Inside every car audio amp is just that. Why not get a used or broke amplifier
and use the DC to DC converter or just fix the whole thing. Yes
there should be commercial units available, but its got to be cheaper
the other way.

greg

 

[Tim Auton]

My idea was to use an amplifier kit from an electronics chain-store
over here in Britain (Maplin for anyone who is interested) and run this
from the line-level output from my car stereo. However, this is where
the problem shows up - the amp requires 30v or so, and as you are
no-doubt aware, a car battery only manages 12 volts.

So, any suggestions?

If you were looking at L86BH, 200W Power Amplifier Module, the
Velleman site says it needs 30V *AC*. That means you'd need a 12VDC -
30VAC 5A inverter, which isn't exactly an off-the-shelf item and nor
is it trivial to make one.

http://www.maplin.co.uk/Search.aspx?criteria=L86BH
http://www.velleman.be/ot/en/product/view/?id=360356

I suggest you try and find an amplifier which runs from 12V; it'll be
much easier. One designed for in-car use, so it can handle the
sometimes ugly power supply cars provide.


Tim

 

[Roger]

Hi there.

Firstly, let me begin by stating that my knowledge of electronics is
somewhat basic, so please dont be offended if I ask a seemingly silly
question.

Don't think you will offend anyone. But bear in mind that 150W+ cct's
can quite easily generate a lot of heat and smoke in the hands of the
inexperienced. Well, let's be truthfull, they often generate a lot of
heat and smoke in the hands of the experienced ;-)

So, you might like to think twice before sticking such a home brewed
contraption behind you car dashboard. If the inspectors discover some
odd looking contraption in the burnt out wreckage of your car they will
probably not cash up on the insurance.

 

[[email protected]]

Inside every car audio amp is just that. Why not get a used or broke amplifier
and use the DC to DC converter or just fix the whole thing. Yes
there should be commercial units available, but its got to be cheaper
the other way.

greg

I didn't think about that one, cheers Greg!

 

[[email protected]]

If you were looking at L86BH, 200W Power Amplifier Module, the
Velleman site says it needs 30V *AC*. That means you'd need a 12VDC -
30VAC 5A inverter, which isn't exactly an off-the-shelf item and nor
is it trivial to make one.

Hi Tim.

The amp I was looking at wasn't a 200w one, it was a little 20w job. I
think this would be a good starting point for me. I reckon the car
stereo amp is putting out 5w RMS at the very most - it's the kind of
thing that has '40wx4 output' written on it. I'm pretty certain it
isn'r 4 x 40w rms, it's more likely to be marketing power, if you see
what I mean.

I suggest you try and find an amplifier which runs from 12V; it'll be
much easier. One designed for in-car use, so it can handle the
sometimes ugly power supply cars provide.

Well, shortly after posting my message, I found something called a
class-T amp that would provide about 20w rms and runs from 14.4v
maximum, so I think this may be a goer. I'll have to look in to it a
bit more though. Thanks for your reply.

 

[[email protected]]

Don't think you will offend anyone. But bear in mind that 150W+ cct's
can quite easily generate a lot of heat and smoke in the hands of the
inexperienced.

OK, first question - whats a cct?!

Well, let's be truthfull, they often generate a lot of
heat and smoke in the hands of the experienced ;-)

So, you might like to think twice before sticking such a home brewed
contraption behind you car dashboard. If the inspectors discover some
odd looking contraption in the burnt out wreckage of your car they will
probably not cash up on the insurance.

Well, true! However, I was not thinking of any monstrous sound system
for my car like the ones in the boy-racer mags, all I want is a nice
clear sound with a decent capacity for bass at higher volume levels. I
know that the speakers matter a lot in these sort of things, but I'm
also aware that an amp that can't supply enough power sounds, well,
bloody awful to be honest!

As I said to the other fella, I've found something called a class-T amp
which I'll look into. I think a stereo one for the mid and high range
speakers, 20watts, and something similar for a bass speaker would be a
good starting point. Thanks for your reply Roger!

 

[YD]

Hi there.

Firstly, let me begin by stating that my knowledge of electronics is
somewhat basic, so please dont be offended if I ask a seemingly silly
question.

I would like to know if such a beast as a high current (around 5A or
so) DC-DC (12v to 30v) converter exists, or if they are (relatively)
easy to make.

The basis of the question is my car stereo. Frankly, the amplifier in
it is little better than weak, unable to deliver a clear sound at
anything above low to mid volume, which is a bit of a problem when I am
driving down the motorway with the windows down.

My idea was to use an amplifier kit from an electronics chain-store
over here in Britain (Maplin for anyone who is interested) and run this
from the line-level output from my car stereo. However, this is where
the problem shows up - the amp requires 30v or so, and as you are
no-doubt aware, a car battery only manages 12 volts.

So, any suggestions?

Thanks in advance for any help,

Roger Melly.

You're probably better off buying a ready-made power module. They have
the DC-DC converter already built-in and come in sizes from reasonable
to much too loud.

- YD.

 

[[email protected]]

You're probably better off buying a ready-made power module. They have
the DC-DC converter already built-in and come in sizes from reasonable
to much too loud.

Hello YD.

Buying something ready made is certainly an option, but half the
interest I had was from the DIY aspect! Cheers though.

 

[Mark]

Hello YD.

Buying something ready made is certainly an option, but half the
interest I had was from the DIY aspect! Cheers though.

look at "bridge amp" like a push pull, and also lower Z
speakers...with these two techniques you can get more power from
12Volts.
Mark

 

[Paul E. Schoen]

Hello YD.

Buying something ready made is certainly an option, but half the
interest I had was from the DIY aspect! Cheers though.

You could get a 12 V to 120 VAC inverter, and then plug in a switching or
linear supply of whatever voltage and power you want. You could use an
isolated 15 VDC supply in series with the 12 VDC you already have and be
close enough to 30 VDC.

If you really want to do it yourself, you can make a low frequency DC/DC
converter by winding a few turns on a toroidal core, and use something like
an SG3526 and some power MOSFETs to drive it. I used a small burned-out
powerstat, but you could also use a CT (200:5 already has 40 turns on it).
A toroidal core rated at 200 VA (60 Hz) will give you 1400 watts at 400 Hz,
and it will work up to at least 1 kHz. At that frequency, you will get
about 1 volt per turn, so you will need only about 12 turns for your
primary and 36 turns for the secondary. A center tap push pull
configuration is easy to do, and the project will be a good learning
experience. If you would like more details I can send you a schematic for
the design I am working on for a converter from (12, 24, 36, 48, 72 VDC) to
360 or 720 VDC. The principles are the same.

Paul