Think there's some thing missing, fluorescent lamp 'A' level.

[ericmark]

Taken from 'A' level text book, is there any way it can work without a ballast?

 

[JohnW2]

Taken from 'A' level text book, is there any way it can work without a ballast?

For a fraction of a second, perhaps, but I imagine it (or something) would soon 'go bang'!

Kind Regards, John

 

[securespark]

I suspect they have left a rectangle out of the diagram that represents the ballast.

 

[ericmark]

I would think it would burn out the heaters, but if it did strike, then there is no current limiting, so yes could very likely go bang. One has to ask how some thing like this arrives in a text book? Don't they have any proof readers?

 

[RF Lighting]

I installed some PL fittings in a pub it must be 15+ years ago and they contained no control gear. Still to this day have not seen this type of fitting again, nor understood how it worked.

 

[Harry Bloomfield]

View attachment 190213
Taken from 'A' level text book, is there any way it can work without a ballast?

Nope, or not for long. Once the discharge is struck, its resistance would be quite low so a lot of current would then be able to flow.

 

[JohnW2]

One has to ask how some thing like this arrives in a text book? Don't they have any proof readers?

Seemingly not - at least, not infallable proof readers.

It might perhaps be ones of those 'perpetuation of an error' phenomenon (most text books plagarise most of the text of earlier ones). I'm sure I've told you before about the inorganic chemical reaction that was first described in a textbook in the early 20th century, and which had subsequently appeared in literally hundreds of textbooks all over the world. It was only in the 60s, whilst I was studying A-Level chemistry, that it was eventually discovered that this widely described 'reaction' simply did not happen!

Kind Regards, John

 

[SUNRAY]

View attachment 190213
Taken from 'A' level text book, is there any way it can work without a ballast?

We installed several fittings would have been 70's which were in service for a long time, certainly well into 90's or possibly 00's which looked exactly like this. A 2 part box just big enough for a starter and connector and a pair of super slim arms for the tube holders about 3" below the ceiling. Instructions warrned about the heat and not to mount on papered ceilings and a massive warning about polystyrene tiles. No I never did know how they worked until we refurbed, it turned out the red and black wires [L&N] were around 40Ω each. I only recall changing tubes once and that was because one got broken and the improved light level made us realise how they had deteriated.

In the time they were there, one of the ceilings had not been painted and there was a definite brown mark from the heat and they creaked a lot while heating and cooling.

 

[Harry Bloomfield]

In the time they were there, one of the ceilings had not been painted and there was a definite brown mark from the heat and they creaked a lot while heating and cooling.

Yep, I have come across resistive 'ballasts' before. They were very wasteful of power, so replaced with much more efficient inductive ballasts. There is nothing in the diagram, which suggests it uses restive ballasts.

 

[SUNRAY]

There is nothing in the diagram, which suggests it uses restive ballasts.

Quite so but in the fitting I referred to they just looked like braided insulation so appeared to be exactly as the drawing.

 

[ericmark]

The problem is, once you see some thing wrong in the text book, you then question everything else in the text book.

 

[bernardgreen]

it turned out the red and black wires [L&N] were around 40Ω each

Reminds me of valve radios which used a three core cable to the mains plugs, Live and Neutral were flexible copper and the third was a resistive wire connected to Live in the plug.

To save me typing more details can be found HERE

 

[ericmark]

There was a resistive lead used in car ignition systems as well, normally from 12 volt battery the lead would give you 9 volt at coil, but when starting the battery volts would drop to 9 volt, so when cranking coil connected direct to battery, so coil always at 9 volt. Seem to remember Ford used the resistive lead, and BMC used a resistor bolted onto the coil, it was common when the resistive lead failed to convert to BMC (Lucas) system.

Of course in UK we had 240 volt not 120 volt so we used large green resistors inside the TV, I had one crack, and could not find a replacement, however realised it was the same resistance as the iron, so wired a 13A socket where the resistor was, and to watch TV plugged in the iron, however if you forgot to turn the thermostat up to maximum, after around an hour, always in the exciting part, the thermostat would turn off TV and by time it had warmed up again you had missed the end of the program.

 

[bernardgreen]

There was a resistive lead used in car ignition systems as well

I recall that the resistive lead was use between distributor and spark plugs to add some filtering to reduce the radio interference ciase by the spark ignition.

I also recall some cars had a resistor fitted in series with the ignition coil primary. This was shorted out when starting the engine to provide fatter sparks in the cold cylinders

 

[Harry Bloomfield]

There was a resistive lead used in car ignition systems as well, normally from 12 volt battery the lead would give you 9 volt at coil, but when starting the battery volts would drop to 9 volt, so when cranking coil connected direct to battery, so coil always at 9 volt. Seem to remember Ford used the resistive lead, and BMC used a resistor bolted onto the coil, it was common when the resistive lead failed to convert to BMC (Lucas) system.

I mentioned that method in an earlier thread - idea was to maintain a good spark, whilst cranking. When cranking a direct 12v supply was connected to the coil, when running coil was fed via the resistance in the loom, or sometimes a separate resistor mounted on the coil.