PSU design II result

Yes, Critical chokes make very good power supplies., posted on August 5, 2015 at 06:48:05
Chip647 Audiophile Posts: 2653 Location: The South Joined: December 24, 2012	The only problems with them is that they can be expensive and they need some real estate to avoid inductive coupling.

RE: PSU design II result, posted on August 5, 2015 at 07:06:20
Al Noakes	It's a result but does not give an insight into current , ripple or anything else . You would be better off publishing a picture of the entire model schematic or posting your PSUD .psu file in text format Al

+1., posted on August 5, 2015 at 10:55:25
drlowmu Manufacturer Posts: 9730 Location: East of Kansas City Joined: January 10, 2005	Regards Al. JM

RE: PSU design II result, posted on August 5, 2015 at 13:41:06
mikeyb Audiophile Posts: 1807 Location: Minnesota Joined: November 8, 2002	That picture simply shows the start up response with an unknown load, not the transient response to a step change in current draw. The later would be far more informative.

RE: PSU design II result, posted on August 5, 2015 at 16:34:47
lovetube Dealer Posts: 3008 Location: Melbourne Australia Joined: June 8, 2003	sorry when I did thge screen shot it moved . here is the whole PSU i still learn to use this progam .

RE: PSU design II result, posted on August 5, 2015 at 16:35:54
lovetube Dealer Posts: 3008 Location: Melbourne Australia Joined: June 8, 2003	done Al. it on my above post

RE: PSU design II result, posted on August 5, 2015 at 17:55:23
danlaudionut Audiophile Posts: 5480 Location: Schenectady Joined: June 6, 2002	Drop the RC and use a 5Y3 rectifier. You get a better result. 10V higher B+ but a lot better. DanL

RE: PSU design II result, posted on August 5, 2015 at 17:58:15
lovetube Dealer Posts: 3008 Location: Melbourne Australia Joined: June 8, 2003	thanks DanL. i will try that and see

RE: PSU design II result, posted on August 5, 2015 at 20:51:36
Triode_Kingdom Audiophile Posts: 10049 Location: Central Texas Joined: September 24, 2006	That's only useful for determining loaded output voltage and ripple content. It doesn't even matter how the supply starts up, unless you live in an area prone to blackouts. :)

RE: PSU design II result, posted on August 6, 2015 at 10:03:44
mikeyb Audiophile Posts: 1807 Location: Minnesota Joined: November 8, 2002	What is the application? I strongly suggest that you get rid of R1 and C3. Unless the connected circuit is a true differential (constant current draw) design, changing current draw in response to an AC signal will cause modulation (changing voltage) at C3 - even with class A amplifiers. While increasing the value of C3 can reduce the modulation, it can not totally eliminate it.

RE: PSU design II result, posted on August 6, 2015 at 17:09:59
lovetube Dealer Posts: 3008 Location: Melbourne Australia Joined: June 8, 2003	it is for Phono preamp and i need more filtering . what is your thought on this ?

RE: Yes, Critical chokes make very good power supplies., posted on August 7, 2015 at 14:15:09
Triode_Kingdom Audiophile Posts: 10049 Location: Central Texas Joined: September 24, 2006	Critical inductance improves the regulation of average voltage with regard to long-term load variations. However, like any series choke, it degrades the supply's characteristics as a voltage source for instantaneous load fluctuations (i.e. audio). Just something to keep in mind. :)

RE: PSU design II result, posted on August 9, 2015 at 10:27:28

mikeyb
Audiophile

Posts: 1807
Location: Minnesota
Joined: November 8, 2002

Remove R1 and C3. With the large valued chokes and caps that you are using, filtering should be adequate without R1/C3.

With an LCLC filter, a critical current must be drawn at all times in order to maintain regulation and prevent the current in L1 from reaching zero. This is usually done via a "bleeder resistor" across the last cap (C2). You can calculate the minimum current draw using the formula:

Lcrit = Vdc / Ima

where Lcrit is the minimum (critical) choke inductance, Vdc is the supply DC output voltage, and Ima is the load current in milliamperes.

For more details, read Henry Pasternack's excellent article on the subject

http://www.audioasylum.com/forums/tubediy/messages/16/165030.html

If the output voltage is too high, find a power transformer with the correct secondary voltage.

RE: Yes, Critical chokes make very good power supplies., posted on August 9, 2015 at 14:01:56

Garg0yle
Audiophile

Posts: 859
Joined: December 1, 2014

"However, like any series choke, it degrades the supply's characteristics as a voltage source for instantaneous load fluctuations (i.e. audio). Just something to keep in mind. :)"

I respectfully disagree with this, I think we had a brief discussion about this before.

If I recall when the voltage is changed across the choke, the collapsing magnetic field stored in the choke releases power.

I will check it out in spice again, I could be mistaken, but is seems to act as a flywheel, so to speak.

Perhaps I will open a discussion later as to not side track this thread.

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RE: Yes, Critical chokes make very good power supplies., posted on August 9, 2015 at 16:19:51

Triode_Kingdom
Audiophile

Posts: 10049
Location: Central Texas
Joined: September 24, 2006

A choke is a current source, the antithesis of a voltage-regulated supply. If it were not followed by filter capacitance, the choke's output voltage would swing wildly in response to even minor fluctuations in load. From this it can be reasonably assumed that, for a given amount of output capacitance, the series-choke supply will perform more poorly against a rapidly changing load. Of course, the choke's contribution depends in large part on the value of the output capacitor.

RE: PSU design II result, posted on August 9, 2015 at 17:19:44
lovetube Dealer Posts: 3008 Location: Melbourne Australia Joined: June 8, 2003	Thanks. i will have a good read on Henry post . LT

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PSU design II result

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