On schematics, there can be a black dot on one end of inductor symbol in
a transformer. What does it mean?

I know, pretty basic, huh?

The black dot tells you the phasing between the windings; which end you
need to hook where in order to avoid a 180 degree phase shift. If you
look at the primary and secondary voltages on the dotted end of each
winding with respect to the undotted end, they'll be in phase.

jawod wrote:
On schematics, there can be a black dot on one end of inductor symbol in
a transformer. What does it mean?

I know, pretty basic, huh?

On 10 Sep 2006 08:59:57 -0700, "
wrote:

The black dot tells you the phasing between the windings; which end you
need to hook where in order to avoid a 180 degree phase shift. If you
look at the primary and secondary voltages on the dotted end of each
winding with respect to the undotted end, they'll be in phase.

Hi Dan, John,

Additionally, the dot is also called the "polarity." That is, when
the input phase is going positive on the primary dotted end of
transformer, all other windings' dotted ends are also going positive.
Yes, this is the same thing as saying their in phase, but when you
look at a schematic it is sometimes easier to think in terms of
polarity, especially when you are looking at ring demodulators.

73's
Richard Clark, KB7QHC

jawod wrote:
On schematics, there can be a black dot on one end of inductor symbol in
a transformer. What does it mean? I know, pretty basic, huh?

It's a phase reference for an AC signal. Otherwise,
there would be the possibility of a surprise
phase reversal through the transformer.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
jawod wrote:

On schematics, there can be a black dot on one end of inductor symbol
in a transformer. What does it mean? I know, pretty basic, huh?


It's a phase reference for an AC signal. Otherwise,
there would be the possibility of a surprise
phase reversal through the transformer.
Dan, Richard and Cecil

Thanks very much. You guys are great!

John
AB8O