From: Spehro Pefhany <speff@interlog.com>

The renowned Mario Van Wiechen <mario.vanwiechen@marandeng.com> wrote:
> Auto battery chragers only use half wave rectifiers and let the battery
> stabilize the output. This allows the use of only 2 diodes to make them
> cheaper.

Nope, 2 diodes give you a full wave rectifier (when used with a center
tapped transformer). The CT transformer is a bit of trade off, the extra 2
diodes are saved, but the transformer has to be heavier because the core
is used less efficiently. You also save a diode drop (at 20A, that's 15W
or so).

Transformer

0----( || )------|>|-------o------- +V
) || ( |
( || ) |
120 ( || )------------------------ 0V
VAC ) || ( |
( || ) |
0----) || (------|>|-------o

They don't have a filter capacitor, they use the battery for that.

Best regards,
--
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Spehro Pefhany --"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
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