High current DC-DC converter

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

snipped-for-privacy@yahoo.com wrote: [snip]

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.

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

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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.

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

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.

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.

OK, first question - whats a cct?!

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!

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.

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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

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