[Boatanchors] Q of electrolytic capacitors

[J. Forster]

Brian Clarke wrote:

> Yes, John,
>
> Great photo. But you can't tell from the photo whether that was due to leakage resistance
> or high ESR. In a Pi filter on a mains PSU, it's usually the cap just after the rectifier that
> goes because it is carrying twice-mains frequency ripple current. And, it's usually the
> growing ESR times ripple current squared that leads to accelerated drying out, reduced
> capacitance and then the second filter cap going.

The power supply has no rectifier. It's a dynamotor, so ESR is essentially not an issue. BTW, the
radio is a WS 19. The 'Mains' is 12 VDC.

-John

> And why the high ripple current? Because the loudspeakers we had were rather poor in
> the LF region and so we under-filtered the rectified mains; as soon as a load was applied,
> the ripple current grew. A typical CR product in those early days was about 0.02.
> Nowadays, we tend to go for 0.15 to 0.3. Sure, we get a higher start-up charging current,
> but the ripple current is much less.
>
> 73 de Brian, VK2GCE.