On Wed, 14 Jan 2009 22:08:38 -0000, "N_Cook"
wrote:

2 Selenium rectifier trade names of the right sort of specs, of the early
1950s, were
Westinghouse Westalite
and
STC SenTerCel
for which the earliest reference I've found is 1951


Selenium rectifiers date from the mid to late 20's I believe.

Kevin