On 9 Jan 2005 21:09:51 -0800, wrote:

I have an indicator on my phase converter. Salvaged from somewhere.
It is a 120 volt bulb, 3/4 inch diameter, and a double contact bayonet
base. The base is 15mm diameter.

I tried for hours to find any conversion from dimensions to bulb
number. No luck.
Can anyone shed some light on where the specs are located for the
various
bulb types?

The catalogs and web pages list hundreds of types of bulbs, and what
base they have, but not the dimensions of the base standards!
How many sizes of bayonet bases are there?
Where can I get one replacement bulb?

Bring it to a sewing machine repair shop and see if they can match it
-- or even JoAnn's fabrics or Wal-Mart. That sounds a lot like the
bulb used in a Singer Featherweight. Yup, just measured one, the base
is 15 mm dia.