swinging choke vs filtering choke

[Ku Chenchen]

I have some swinging chokes (4/20H, 200ma), can I use those in the
place of filtering choke, assuming the amp draw 150 ma current, thanks.

Chenchen

[Nathan Stewart]

Ku Chenchen (c...@ix.netcom.com) wrote:
: I have some swinging chokes (4/20H, 200ma), can I use those in the

: place of filtering choke, assuming the amp draw 150 ma current, thanks.

From what I know, you can use them anywhere you can live with about 4ish H
of inductance, given your current draw. What I'd like to know is:
1) Aren't all chokes swinging chokes to some degree?
2) What makes a choke a "swinging choke" - besides the fact that it's
inductance changes with DC load - I mean how do I wind a choke so that
it is swinging or non-swinging?
3) Dependant on 1 & 2, is there any rule of thumb for taking say a vanilla
X.x H Choked rated for YYY mA, and using it as a swinging choke for
XX.x H / YY mA? (Eg, what can I expect this choke to do given reduced
current draw?)
4) Would you like to sell or trade some of that iron?
______________________________
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[EJTHETA]

A "swinging choke" is one that is designed to to have high inductance at
low current and lower inductance at high current. It improves supply
regulation where the load current varies a lot. It will work in an amp
power supply, but may not give any better performance than a regular
choke, because the current in a typical Class AB tube amp doesn't vary
over much more than a 2 to 1 ratio.

Bruce Macmillan

[Bob Bruhns]

You can use that "swinging" choke as a filter choke. At 150 mA it will
probably give you about 5 or 6 henries of inductance. Swinging chokes
are intended for use as the input filter inductor in inductive-input power
supplies. When used in this way, the "swing" effect of these chokes
improves the load regulation of the power supply. A swinging choke will
reduce voltage sag caused by high load current, but it will not
compensate for line voltage variations which are not caused by power
supply load variations.

With an inductive input filter, DC output is lower with more inductance
and higher with less inductance. The inductance of a swinging choke is
high at low current and low at high current. So, at high current, where
power supply voltage sag problems are the worst, the swinging choke
provides the least inductance, and the inductive-input filter (of which
it is the inductance) produces more output voltage than it would have
with a constant inductor, and so - bottom line - voltage sag is greatly
reduced.

Swinging chokes are a "natural" because their inductive variation
results from core saturation, which is unavoidable, and best achieved
with relatively small core dimensions and weight. Ordinarily one would
think that for minimal sag, huge and overrated components would have to
be used. Yet here a smaller filter choke can produce better regulation.

Bob Bruhns, WA3WDR, bbr...@li.net