[Milsurplus] [ARC5] Cool New DC-DC Converter

[Bruce Gentry]

     Does anyone know how manufacturers assign or condition new 
electrolytics for their working voltage?   As long as the power factor 
is good to begin with, I have had very good results reviving 
electrolytics that had excessive leakage at or below their operating 
voltage by applying the rated voltage through a current limiting 
resistor.  I use no more than 2 milliamps and am patient, reducing the 
current if needed to prevent heating beyond a temperature pleasent to 
hold.  A multi section condensor may take a few days to reform, but once 
they do, the power factor/ESR usually improves as well as capacitance 
and leakage.

      Bruce Gentry, KA2IVY


On 3/18/18 1:08 PM, Dennis Monticelli wrote:
>   All 'lytics pass current (we call it leakage) as part of their 
> natural ongoing process of oxide decomposition and reformation.  
> Operate a 450V cap at 50V for a long period of time and it will reach 
> a new equilibrium, eventually becoming a 50V cap.  To use that cap at 
> much higher than 50V safely would require slowly reforming 
> (re-thickening) of the now very thin oxide layer until an new (high 
> voltage) equilibrium is reached.
>
> We see a version of this situation whenever we power up an old piece 
> of equipment whose lytics have been dormant for years.  If they 
> haven't dried out they will properly reform if given the chance. That 
> is why we are careful to severely limit the current into those caps 
> while we allow the oxides to slowly reform.  Slow growth creates a 
> better quality of oxide and insures that the negative affects of 
> self-heating are keep at a minimum.
>
> Dennis AE6C
>

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