5 Jun
2010
5 Jun
'10
2:33 p.m.
On 5 Jun 2010 at 11:25, Tony Duell wrote:
It's very easy to make a filament bulb last a very
long time -- you
just under-run it. I would guess if you connected a 230V bulb to 110V,
it would give off _some_ light (not much, but you would see it glow),
and it would continue to do so for a very long time.
The downside, of course, is that the efficiency is very low. So to get
enough light to see by, you have to pay for a lot more electrical
energy.
It's surprising how little voltage it takes to get a glow out of a
lamp--a 120V incandescent will exhibit a visible glow on as little as
12V.
During the early years of WWII, many of the amateur radio
publications ran ads from RCA that advised dropping the
heater/filament voltage on transmitting tubes by about 10% and
derating them somewhat. Apparently this could result in a doubling
of useful life.
I believe that some early vacuum-tube computers ran heaters somewhat
below the "nameplate" ratings simply to improve reliability.
--Chuck