[TheForge] Shop Lighting

[Grover Richardson]

Possibly I used the word arc in correctly.  The gas inside the tube, hhmm,
plasma??  Is that the correct word?  It conducts.  When it conducts, it
drops the Voltage across the gas, the Voltage dependant upon the length of
the gas column.

Don't worry about threatening you with physics, I'll  hide also<G>.

>*>-----Original Message-----
>*>From: theforge-bounces at mailman.qth.net 
>*>[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Mike Porter
>*>Sent: Monday, February 27, 2006 6:18 PM
>*>To: Sponsored by ABANA
>*>Subject: Re: [TheForge] Shop Lighting
>*>
>*>
>*>I thought it was impedance (sp?) in the electrical circuit 
>*>that  tends to 
>*>make the arc persist? I can remember asking my instructor 
>*>why it would take 
>*>energy to collapse and electrical field too, rather than 
>*>just to establish 
>*>it. He went to the blackboard and started writing out long 
>*>as your arm 
>*>equations while talking about right angle atomic holes.
>*>Mikey
>*>Don't you threaten me with physics, 'cuase I'll run and hide!
>*>----- Original Message ----- 
>*>From: "Grover Richardson" <grover.richardson at gtri.gatech.edu>
>*>To: "'Sponsored by ABANA'" <theforge at mailman.qth.net>
>*>Sent: Monday, February 27, 2006 1:30 PM
>*>Subject: RE: [TheForge] Shop Lighting
>*>
>*>
>*>Ahh.  You are sharp!!  And have the right idea<G>.
>*>
>*>Ok, here's what is happening.  60 Hz or 60 cycles.  A full 
>*>cycle is 360 degrees of operation.  A 120 Vac sine wave goes 
>*>from 0 Volts to positive 169.7 Volts (120 Volts is rms, or 
>*>root mean square, so the peak Voltage is 1.414 times the rms 
>*>value), back through 0 Volts, down to minus 169.7 Volts, and 
>*>back to 0 Volts for a full 360 degrees of operation.  That 
>*>is one cycle.
>*>
>*>The important part is that the sine wave peaks twice.  And 
>*>the fluorescent bulb turns on twice for each "cycle" of 
>*>power.  Once for the positive portion and once for the 
>*>negative portion.
>*>
>*>For those who like additional information.  It takes a 
>*>certain amount of Voltage across a gas filled tube for the 
>*>tube to turn on.  Then, when it turns on, the Voltage drops 
>*>to a value about 75% (generic here) of the turn on Voltage.  
>*>The gas tries to maintain that Voltage drop across the gas 
>*>no matter what.  Physics, I don't remember why.  So, the 
>*>ballast limits the current through the bulb so that it 
>*>doesn't burn up or pop the breaker. When the Voltage drops 
>*>below a certain value near that "on Voltage," the bulb stops 
>*>conducting.  Oh yes, when it conducts, it produces that 
>*>light effect that we like.  Only problem is that the light 
>*>color that is produced is not what we wish to see.  So the 
>*>bulbs are lined with phosphors that take the light and turn 
>*>it into a light color that we do like.
>*>
>*>The early regulator tubes (0A3, 0B2) were gas filled tubes 
>*>and did the same duty as zener diodes today.  But they were 
>*>more sloppy in the regulation. Every day in the Navy, I went 
>*>to my power supplies and adjusted them for proper Voltage, 
>*>first thing.
>*>
>*>Woof (I bark better than most dogs<G>)
>*>
>*>Yes.  Faster than we can see.  As I remember it, film 
>*>projectors flick at 24 frames per second.  Some people can 
>*>barely perceive that.
>*>
>*>
>*>
>*>
>*>>*>-----Original Message-----
>*>>*>From: theforge-bounces at mailman.qth.net 
>*>>*>[mailto:theforge-bounces at mailman.qth.net] On Behalf Of GHS
>*>>*>Sent: Monday, February 27, 2006 3:47 PM
>*>>*>To: Sponsored by ABANA
>*>>*>Subject: Re: [TheForge] Shop Lighting
>*>>*>
>*>>*>
>*>>*>Grover Richardson wrote:
>*>>*>
>*>>*>>
>*>>*>>Actually 120 times, but that's ok<G>.  But yes, there 
>*>are effects 
>*>>*>>though we can't see them. *>>
>*>>*>>
>*>>*>>
>*>>*>If I had the time I'd build a strobe and check you out.
>*>>*>As I remember it is OFF 60 times a second. It is also ON 
>*>60 times a
>*>>*>second. Thus the 120. I barely remember the explanation.
>*>>*>
>*>>*>Are the fluorescents essentially a DC operation? (Responding
>*>>*>to only one
>*>>*>half of the wave?)
>*>>*> If so, I am correct.
>*>>*> If not, you are.
>*>>*>Never claimed to actually understand that stuff.
>*>>*>
>*>>*>Either way it is far faster than we perceive.
>*>>*>
>*>>*>Mike Graf
>*>>*>
>*>>*>-- 
>*>>*>Please visit us at http://www.gaudeteforge.com/
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