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Picture upgrading your tranformer to add some 50% more voltage. Then, add a passive 1st-order low-pass (choke) & high-pass (cap) filters @ 60Hz. Follow each with a full-wave rectifier. Each one is 45º from the power source (including the truncated portion) & 90º from eachother. Thus, the corporate rectifed waves are recombined into double frequency waves which wil halve ripple & mask diode noise. How funky is that? I just came up with this sh!t a week ago & can't find a down side. Can you?BTW, the exta 9% voltage will probably be used up in inefficiencies.
....just my 2¢
» Mart £ «
Planar Asylum
where the speakers are thin but the music is anything but
Follow Ups:
Tom §.
The downside is that you can't load down the filters or you lose the phase shift you sought to gain. Or you can make it a 2nd order filter with adjustable phase shifts and then your load still cannot shift on you after tuning this in.Kurt
I'm not sure I know what you mean. I was suggesting you find out what the input impedence is on the full-wave rectifers are & wire either the appropriate value cap or choke to XO. I don't see what you mean by loading down. Are you talking additional current/voltage or what?
....just my 2¢
» Mart £ «
Planar Asylum
where the speakers are thin but the music is anything but
> > > I'm not sure I know what you mean. I was suggesting you find out what the input impedence is on the full-wave rectifers are & wire either the appropriate value cap or choke to XO. I don't see what you mean by loading down. Are you talking additional current/voltage or what? < < <Yes, you can do that. I made a mistake about how much phase shift you need for achieving "quadrature", something you're after - 90 degrees total, not each. Let me try to correct myself and clarify this.
The load (input impedance on the rectifiers) cannot change or the phase shifting inductors and capacitors will not be the correctly tuned values that will make these two outputs in quadrature (90 degrees apart in phase from each other). If it's not perfectly in quadrature then there will be fundamental frequencies of 120 Hz, not just 240 Hz which is what you seek. Then you still have to filter 120 Hz, maybe not as much as the "normal" way, but you still have to do it. Also, it costs you a cap and an inductor to achieve this quadrature, something that could have been put to use filtering the 120 Hz, and you could make a well "regulated" choke-input supply.
It's a neat idea, really, but for a real practical PS in a small package the most common way to go is to use a switcher and filter a very high frequency and regulate it while you're at it. The disadvantage there of course is the switching noise.
Heck, just try out your idea. I bet you can make it work fine for a fairly constant load like a light bulb. I just don't know if you're going to end up buying anything big when it comes to hum rejection and parts savings, especially under dynamically changing load conditions. But try it and let us know how it worked. I could be full of it.
Kurt
I was talking to an Electronic Technician. He said the rectifier impedence reduces in order to draw more current from the wall. I assume he's talking Class AB. Is this true, or is he full of it?
....just my 2¢
» Mart £ «
Planar Asylum
where the speakers are thin but the music is anything but
> > > I was talking to an Electronic Technician. He said the rectifier impedence reduces in order to draw more current from the wall. I assume he's talking Class AB. Is this true, or is he full of it? < < <It's not the impedance from the rectifiers and transformers and wall outlet that concerns me, it's the current draw on it that affects the phasing of the RC and RL circuits that will go out of whack when R changes on you. That R is the voltage/current delivered from the power supply to the amp circuit, or the load on the power supply. Rectifier impedance will drop as more current is drawn, but that hardly affects what the load is doing to the quadrature phase splitting circuit you have. It's a drop in the bucket in comparison, and cannot be expected to compensate.
Kurt
Yes, that was exactly what I was asking? So, if R is halved, the f3 on the low-pass is halved to 30Hz and shifted 18.435º more, while the f3 on the high-pass is doubled to 120Hz, and are phase 36.87º more apart or together depending on your perspective. Thus, the net rail voltage drops some 36.75%.Since class A is supposed to maintain a constant rail voltage does it's input amp's impedence change too?
....just my 2¢
» Mart £ «
Planar Asylum
where the speakers are thin but the music is anything but
> > > Since class A is supposed to maintain a constant rail voltage does it's input amp's impedence change too? < < <It's supposed to, but it also changes due to its own nonlinearities. A preamp is perhaps a better candidate to try this scheme since the loads are relatively more constant by virtue of the fact that it runs small signal compared to an amp that runs large signal.
Kurt
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