You could determine the light-current inductance by hooking it in series
with a suitable capacitor, then using an audio generator and a scope to
find resonance.
It's most likely they are indeed swinging chokes. If not, they'd again
most likely be wired up to resonate with a fairly small capacitance,
something like 0.1uf. (that makes a resonant choke filter at 159hz, a
little above the 120hz ripple frequency as cussed and discussed on this
list)
So:
. Find a decent-quality 0.1uf capacitor. (electrolytic will work, but
not my first choice)
. Hook the cap up in series with the choke
. Set your audio generator to 40hz or so to start with
. Put your audio generator and scope (or AC voltmeter) across the pair
. Slowly increase the frequency of the generator until you see the
voltage "spike", then tune the generator for maximum voltage.
The resonant freq is then 1 / (2 * PI * SQR(L * C))
Where:
"SQR" means Square Root
PI = 3.141592654 or thereabouts
and L and C are in equivalent units. Farads and Henries, microFarads and
Microhenries, etc. Doing a little algebra will derive the inductance
given the other two, *or* here's a list of approximations for 0.1uf:
159hz 10 Henries
225hz 5 Henries
355hz 2 Henries
500hz 1 Henry
Note:
The only way to know the saturation current inductance of a swinging
choke (that I know of) is to saturate it, sorry.
Online resonance calculator:
http://www.deephaven.co.uk/lc.html
My .02, adjust for your local currency as appropriate.
73,
Jim N7CXI
On 3/9/2012 10:55 AM, Mike Lucas wrote:
> I'm trying to characterize two filter chokes from 4x1 amps, other
> than big and heavy. Can someone
> suggest a procedure, literature, or visual methods to identify what I
> have? Am I safe in assuming that
> they are swinging chokes? Originally from W4GD supplies, weight is about
> 25 Lbs each, although they
> are of different construction.
>
> Thanks, Mike W5CHR Memphis
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