29 Jul
2007
29 Jul
'07
11:30 a.m.
On Saturday 28 July 2007 14:38, Brent Hilpert wrote:
William Donzelli wrote:
A lot of TV's from around that period or a little later used selenium
rectifiers directly off the line (no power transformer) with a fair whop of
capacitance in the filters (very low impedance on both sides of the
rectifier). I'm guessing, but surgistors might have been used to limit
initial charge current, rather than for the sake of the filaments. Selenium
rectifiers have more ON-resistance than silicon diodes but I'm not sure if
it was enough to save the junctions in such circumstances.
I remember having an assembly consisting of a pair of those, rated at 500mA
(you could tell by size :-), and a couple of 100uF caps, which in those
days was a pretty big cap, in a voltage-doubler configuration. I probably
salvaged it out of some old TV...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Surgistors were very popular in the 50's as either an add-on for TV
receivers or as part of the original chassis.
Filled with the finest snake oil available...