>
>Regarding the question of the preferred HV P/s design, a full wave bridge
>vs. a doubler, I think the nod goes to the brdige for several reasons.
>
>First, I think the G3RZP comment about higher peak currents refutes AG6K's
>comment about wire size. If the currents were equal, Rich would be correct
>- however the transformer currents are not equal for a given output load
>current.
? What I am essentially saying is that for equal DC output voltages
and currents using similar cores, a FWB winding has More than four times
as much resistance as a FWD winding.
> Conservation of energy applies, so if the rectifier circuitry
>raises the output voltage, the input current must increase. The analogy is
>somewhat equivalent to an impedance matching transformer.
>
>Second, the voltage doubler circuits typical to ham amplifiers are in
>reality two half-wave circuits with the outputs stacked. The percent
>voltage regulation for a full wave bridge is significantly superior to a
>half-wave circuit.
? depends on the losses in the transformer, the electric-mains'
resistance, and on how much C is used in the filter.
> Two half-wave rectifiers are not going to be superior
>to a full wave bridge if regulation is the criteria.
>
? During positive and negative cycles in a FWD, filter capacitor
charging is taking place.
>IMHO, either circuit will work fine with the appropriate transformer.
>There may be other factors too - for example, if your filter cap is a
>single oil-filled unit, I don't see how you can use a doubler without
>buying another, identical cap. On the other hand, the rectifiers in a
>doubler only carry half the current so this might allow some flexibility in
>component sizing.
? did you mean to say 'in a bridge', Dave?
>
>Hmmm...with regards to my posting a week ago about 2A diodes to run two
>amps off one supply, has anyone tried running two rectifiers off one
>transformer to power two amps? My engineering intuition tells me that
>there might be a problem with a FWB, because if you look real close certain
>diodes will wind up in parallel. However, if the two rectifiers were half
>wave this would not occur. The idea of using half-wave vs. full wave might
>sound like heresy, but if it works OK in doublers why would it not be
>suitable in a single rectifier?
? because a doubler is full-wave -- i.e., current flows on both half
cycles. The trouble with half-wave is that DC flows in the transformer's
secondary winding.
- later, Dave
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|