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Old 23rd February 2012, 05:12 PM   #691
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Quote:
Originally Posted by danielwritesbac View Post
I'd like to hear about some deluxe power supply options for both regulated and unregulated power that are really good with Circlophone.

Of course Circlophone does perform well with a really basic power circuit, and although that is true, I am curious about clean power, and I am especially curious about decreasing the harmonic influence of the power supply, by using a clean / higher quality power supply.
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Old 23rd February 2012, 05:26 PM   #692
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If one needs to limit the voltage to a level safe enough for the transistors, here is an option (but, of course, it shifts the Vceo requirement to the supply transistors).


It is crude, minimal, but will not play silly tricks unlike the previous example.

It also includes a foldback limiting.

Hope this settles the matter once and for all.
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Old 23rd February 2012, 07:27 PM   #693
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Other option, why not opt for an (almost) existing, nice, sophisticated design like this one:
Power supply cap multiplier with electronic protection
A bit complicated, but that's also part of the charm.

I personally prefer to concentrate my efforts on the amplifier, making that kind of accessory redundant, but that's a matter of taste.
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Old 23rd February 2012, 08:16 PM   #694
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Elvee, should I apply servo compensation values (2.2n+1K) as in CFP schematic in real circuit or do you suggest for to stick with original values? Have lower valued parts any advantage here if there isn't any stability issue?
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Old 24th February 2012, 06:55 AM   #695
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If you build the CFP version, you should use the specific CFP compensation components.
Doing otherwise would compromise stability.

Be careful anyway, contrary to the original Circlophone, that variation has undergone only minimal tests, and there could be unpleasant surprises.


Make the first tests on a dummy load to be sure not to toast your tweeters
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Old 24th February 2012, 09:12 AM   #696
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I have applied CFP version to powerflux pcb. It works fine with specific compensation values. But I haven't applied the network at feedback resistor, so could you confirm that it should be ok or less critical than other alterations? I know that I have to respect the scheme as what it is but I would ask this one due to space requirements on pcb.
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Old 24th February 2012, 09:31 AM   #697
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Quote:
Originally Posted by terranigma View Post
I have applied CFP version to powerflux pcb. It works fine with specific compensation values. But I haven't applied the network at feedback resistor, so could you confirm that it should be ok or less critical than other alterations? I know that I have to respect the scheme as what it is but I would ask this one due to space requirements on pcb.
It is stable in that configuration, that's how I physically tested it, but simulation shows a very narrow stability margin.

For stable and safe operation, the new values should be applied (with caution, as this has only been tested in sim).
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Old 24th February 2012, 11:11 AM   #698
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A slightly improved version of the supply:
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Old 25th February 2012, 05:21 PM   #699
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Quote:
Originally Posted by Elvee View Post
A slightly improved version of the supply:
That is looking really elegant.
I've got a few questions:
Does it reduce ripple?
Can it be set to 40v?
What happens if input voltage is lower than the zener?
Thanks!
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Old 25th February 2012, 05:45 PM   #700
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Quote:
Originally Posted by danielwritesbac View Post
That is looking really elegant.
I've got a few questions:
Does it reduce ripple?
Yes, the sim shows the circuit in full action: the magenta trace is the input voltage having a 20V/120Hz ripple level, and the output is simultaneously loaded by a current varying from 0.5 to 2.5A at 1KHz.
Even under those conditions and a 2V operating margin, the rejection remains good.

Quote:
Can it be set to 40v?
Yes, any zener or combination of zeners giving that voltage is suitable: 39V if 1V is not a problem, or two 20V, or 18V+22V, etc.
Quote:
What happens if input voltage is lower than the zener?
It degenerates into an electronic filter (not with the insane level of ripple shown there: with a more normal level of several volts):
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