question about dc filter choke in power supply

[K4KGW]

The extra voltage you get with the cap in the circuit is due to what is called
the "flywheel effect." It's due to storage of some of the peak voltage occurring
at the top of each cycle.  In other words, the cap doesn't discharge fully when
the applied voltage hits zero as it crosses the zero point in the cycle, then it
gets pumped up again as the polarity reverses.

For choke input filters, the DC output voltage should be .9 times the
transformer secondary voltage.  For capacitor input, it should be 1.414 times
the secondary voltage.

All this is in the power supply section of any ARRL handbook, altho the
explanation may be a bit more complicated.

73,

Keith

Lane Zeitler wrote:

> The next project is a dc power supply that will go as high as 4500 vdc at 1
> amp CCS. I will be using a new Dahl xmfr and a dc resonant filter choke
> followed by a cap. This is going to be the universal power supply for
> numerous amp projects.
>
> Scenario: Output E of one of the taps is 2400 vac. Using a full wave bridge
> followed by a resonant choke I get 2150 vdc at the output; approx. 90%. This
> is where it should be using ony a choke.
>
> Now follow the choke by a cap. In this case 15uF at 5 kv (just happened to
> be in the junk box). Now the output voltage is 2480 vdc.
>
> The "output factor" went from .9 to 1.05.
>
> Why the increse in output voltage when the cap is in place?
>
> 90% of xmfr secondary voltage with just choke and 105% with the choke
> followed by the cap.
>
> I am sure the answer is very basic but for some reason I lost the concept.
>
> Help!
>
> Lane Zeitler
> Ku7i
> San Diego
>
> --- --- --- --- --- --- --- --- --- --- --- --- --- --
> To subscribe: listserv at listserv.tempe.gov
> and in body: subscribe BOATANCHORS yourfirstname yourlastname
> To unsubscribe:  listserv at listserv.tempe.gov
> and in body: signoff BOATANCHORS
> Archives for BOATANCHORS: http://www.tempe.gov/archives
> --- --- --- --- --- --- --- --- --- --- --- --- --- --

--- --- --- --- --- --- --- --- --- --- --- --- --- --
To subscribe: listserv at listserv.tempe.gov
and in body: subscribe BOATANCHORS yourfirstname yourlastname
To unsubscribe:  listserv at listserv.tempe.gov
and in body: signoff BOATANCHORS
Archives for BOATANCHORS: http://www.tempe.gov/archives
--- --- --- --- --- --- --- --- --- --- --- --- --- --