[Amps] How much electrolitic for a HV supply ?

[Tom Rauch]

> It's mostly a question of availability of suitable Caps. A 
> well suited
> common type is 450V/220uF, you could get by with 6 in 
> series, but that
> is cutting it very close, prudence would say use 8 in 
> series giving a
> reasonable margin on V and some 27.5uF - that'll do at 
> least up to 500mA
> and likely substantially more.

Actually the ESR of the AC source, the load resistance, and 
the rectifier type determine the ripple and dynamic 
regulation.

In short form:

The higher the transformer ESR (equivalent secondary 
resistance), the less important capacitor size is for 
anything. This is because the supply starts to act like a 
R/C filter with the R distributed throughout the AC system 
feeding the rectifier.

There will be a point where going beyond a certain 
capacitance does nothing at all. That point is very low with 
a high resistance transformer.

As the transformer and power mains get better and better, an 
improvement can be had using more and more capacitance.

At 2000V and 500 mA with a transformer ESR of 200 ohms 25uF 
is acceptable

At the same voltage and current with a transformer ESR of 20 
ohms values up to 250uF would continue to reduce ripple.

73 Tom