E Z Peaces wrote:
Boden wrote:
E Z Peaces wrote:
Jeff Wisnia wrote:

The Daring Dufas wrote:



I had a friend some years ago who ran the communications
division of the local power company. This was back when
they had HF radios for communications and the techs actually
had to know something about electronics. They would get
electronic interference complaints which were often traced
to doorbell transformers. It was a very common problem and
one that many people don't even think of today.

TDD



Sorry, but I have a hard time believing that.

If it was "a very common problem", can you offer a cite proving
that a 60 hz transformer and 10-50 feet of unshielded wire with 24
vac on it can cause interference at radio frequencies?

Wouldn't you expect that if that story was true those big pole pig
transformers and all that higher voltage wiring running on the
poles on nearly every street would have caused the radios to melt?
G

According to the FCC Interference Handbook, defective doorbell
transformers are often a source of interference to TVs and other
household electronics. It may be a neighbor's transformer.

Yes.

I think it happens when part of the core comes loose and vibrates.

Nope, that cant produce electrical interference.

If the Guberment says so it must be so. I just don't believe it.

Several electric utilities say so.

Not that last bit of yours they dont.

It can also come from microarcs in transformers on poles. When they get a complaint, they check poles with an
ultrasound detector to pick up noise from an arc.

Different effect entirely.

When a doorbell transformer fails, I imagine it's usually an open primary.

Yes, because thats the thinnest wire.

When it first opens, I imagine the vibration of the
transformer could keep the break arcing indefinitely.

Nope, you wont get vibration if its got an open primary.

You dont even have enough current to maintain the arc. Completely different to pole transformers.