[ale] OT: Disposal of standard fluorescent lamps?

[Chris Ness]

On Mon, 2011-03-28 at 16:19 -0400, Jim Kinney wrote:

> 
> 
> 
> On Mon, Mar 28, 2011 at 3:53 PM, Greg Freemyer
> <greg.freemyer at gmail.com> wrote:
> 
>          dimmer's save electricity too unless you
>         keep them at max. most of the time.
>         
>         
> Not sure on that. Most dimmers are just a simple rheostat device
> (voltage divider). They get pretty warm in use. Some are switches that
> vary the "on" time to keep the lamp lit. Those will save power. But
> those also hum badly and provide some nasty noise back into the AC
> line. Run a speaker cord near a dimmer and listen for the fun.
> 

NO! Most dimmers are not simple rheostat devices! They work on an
entirely different principle, which is why they do not generally work
with traditional (magnetic ballasted T-12) fluorescents. The dimmers
work with a diac/triac type device and a toroidal coil to distort the
wave form of the AC current. Effectively, the voltage peak the same
positive and negative cycles as before, but for a shorter period of time
during the 1/120th of a second that each half of the cycle is active.
With an incandescent, the filament does not heat as much due to the
shorter time and hence less light. On the other hand, a fluorescent tube
is 120  ≅200vac lightning bolts a second through a gas comprised of a
mercury salt which is gaseous at room temperature (hence the 4vac
heaters at each end). Dimming by reducing the duty cycle of the AC
allows the mercury to precipitate out of the gas after a short period of
time and not conduct the electricity. (which will also happen if you do
not make good connections with both pins)

The new T-8 fluorescents and electronic ballasts have their own problems
with dimming.


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