On Sat, 07 Jan 2012 21:18:16 -0600, The Daring Dufas
wrote:

On 1/7/2012 5:28 PM, Tegger wrote:
wrote in
:



The two pin ones have bimetal strip(s) inside a neon tube. The heat
from the discharge from the neon bends them to make contact. When the
tube strikes the voltage across the strips is reduced hence no
discharge& they then remain open.



I'm having a bit of trouble wrapping my head around this.

Do the ionized gases in the tube present less resistance to current-flow
than the tiny air-gap formed as the starter contacts begin to re-open?


The glass envelope of the starter is basically a neon lamp with a
bi-metal short. When current first flows through the starter, the
bi-metal strip heats up and pulls away from the other terminal and
if current is flowing through a good florescent tube, there is enough
current/voltage to light off the neon in the starter. The heat from
the lit neon keeps the bi-metal strip hot enough to stay bent away from
the other contact. When you hear a click, click, click along with the
ends of a darkened florescent tube glowing on and off, it's usually
because the tubes have worn out and no current is flowing through the
lit tubes so the starter keeps heating up and cooling down as it tries
to heat the filaments in the tube ends to ionize the gas in the tube and
start the reaction that ionizes all the gas in the tube so it glows. The
ionized gas is what conducts electricity to keep the neon
gas in the starter lit. I hope this helps you understand how it works.

TDD
Not exactly how they work, guys.

The glow tube, in series with the filaments and the ballast
incorporates a normally open switch in parallel with the glow tube.
..When power is applied, a glow discharge takes place heating the
bimetal contact. A second or so later, the contacts close - which
causes the current - limited by the ballast - to flow through the
filaments - heating them up, emitting electrons so the flourescent
tube can fire. The contacts short out the starter glow tube, so it
shuts down, allowing the switch to cool and open. When the contacts
open. the inductive kick generated at the instant of opening triggers
the main discharge in the fluorescent tube. . When the main tube
fires, the voltage across the tube is below the firing voltage of the
neon starter glow-tube so it does not glow, and the filaments stay
un-lit.
If the tube extinguishes, or fails to light, the voltage across the
tube increases to the firing voltage of the neon tube, and the starter
attempts to re-fire the tube, repeating the sequence.