by Eeyore <rabbitsfriendsandrelations@[EMAIL PROTECTED]
>
Apr 22, 2008 at 07:14 PM
Ian Thompson-Bell wrote:
> Iain Churches wrote:
> > "Eeyore" <rabbitsfriendsandrelations@[EMAIL PROTECTED]
> wrote
> >> Iain Churches wrote:
> >>
> >>> The standard 6V3 winding would give 8.8V DC.
> >> Not with rectifier voltage drops it won't. More like 6.8V.
> >
> > I did not include the rectifier losses.
> >
> > The AC is at about 235V here this afternoon. I have a
> > Welter mains transformer on the bench in front
> > of me. The heater winding is 6.3V at 3A reg 5%. With
> > a BR156 rectifier and 10 000µF and drawing 3A I measure
> > 7.6V across the electrolytic. What does a SS regulator
> > require?
>
> Depends what you measure it with - a regular ac meter will not show the
> ripple.
>
> Given c.dV = i.dt then dV(pp ripple) = i.dt/C and using your values I
get
>
> dV = 3Ax10mS/10,000uF = 3V pp ripple!! assuming 50Hz mains and full wave
> rectification.
The conduction period will be about 2.5 - 3 ms reducing that 10ms to about
7
ms. That gives 2.1 V pk-pk so about 750mV rms by my calculation.
Graham
