wrote:
On 13 Sep, 16:18, "Bob Eager" wrote:
On Thu, 13 Sep 2007 11:47:27 UTC, wrote:

Hi all,

Just an academic question.

What used to be used in Car Battery charger to convert the AC - DC
before silicon diodes/bridge rectifiers came along?

Any of the following:
vibrator rectifier
synchronous motor with commutator rectifier
tungar mercury discharge diode
selenium rectifier stack

AFAIK the old electrolytic rectifiers werent used
in commercial car chargers, but quite possibly in home made ones.

Vacuum valves were no use for this task.


Supplementary:

What used to be used in car battery chargers to convery 240v to 12v when
the mains was DC?

(my train set used a small rotary converter)

Any of the following:
series impedance, no transformation or isolation
vibrator & transformer with synchronous rectifier
motor generator


NT