there are a couple of versions - first the simplest series choke an starter, just like a 4ft tube,  herer the cap is just accross the mains as a power factor correction, a sort of impedance match between the 230V mains and the 150 or so of the tube once struck.

Better, especially in cold weather, were the ones with the ballast more like a tapped transformer,  so the heaters had their own windings. and the strike voltage was a bit  higher. Again cap for PFC.

Then there were resonant starters, where the cap has to be matched to the series choke and tune to 50Hz - here the cap goes where the starter would. and as the series resonance builds, the voltage on the tube rises, as does the filament current, until something strikes, or the filaments blow open cct. Very fast to strike, but needed cap and choke to be a matched pair and no good on gensets with poor frequency control.

Mike

Thankyou mapj1 thars very helpful  

Happy birthday! 

Try getting a flory starter (or tube) nowadays. I have a starter on order from a local plumbers' merchant.

FWIW, Kelly Marie Angel, you are a youngster. I shall become an OAP tomorrow. 

A number of circuits existed for 8 foot fluorescent lamps.

The simplest was a series choke with a glow starter across the lamp. Any capacitor was simply to improve the power factor and played no part in lamp operation.

Note that the glow starter had to be a special type sold for 8 foot lamps. A universal starter wont work. This circuit needs 240 volt mains for reliable operation and tends to be unreliable on European 220 volt mains.

The second type was known a "semi resonant start" this used a capacitor in series with one winding of the ballast. This capacitor was a vital part of the lamp circuit, if the capacitor reduced in value as it aged then starting became unreliable and light output was reduced. No starter was needed. Worked on 220 volt mains.

A third type used a step up transformer, with a high reactance so as to limit the current. Simple and reliable, works even on 100/110/120/127 volt mains. Common in countries that use these voltages. Any capacitor was simply for power factor correction and played no part in lamp operation.

Also existing were electronic ballasts, never much used in the UK but used overseas.

I have seen very old circuits that used a 4 pin thermal starter, the heater connections were in series with the choke, and the starting contacts connected across the lamp, as with glow starter. Thermal starters are now extinct.  They worked on DC mains, but only for the shorter lamps, not for 8 foot  lamps unless a 300 volt+ supply was available.

The first place I worked in had an 8 foot tube in the coldest part of the factory it often struggled to start in winter partly downtown the cold and also our mains was often below 220 volts especially in winter. Poor thing never stood a chance!

In my youth, we had a similar problem with a number of 8 foot fluorescent lamps in cold weather and low supply voltage.

I fitted a 30 volt transformer, wired as an auto-transformer to increase the supply voltage by about 27*  volts, so with an actual measured voltage of 210 volts, the lights received 237 volts and worked much better. To avoid overstressing the lamps and ballasts, I fitted a changeover switch so as to supply straight mains, or mains plus 27 volts. The two switch positions were marked "summer" and "winter" Worked for years !

* The transformer was ratted to supply 30 volts with a full 240 volts input, used on the reduced mains voltage the output was reduced in proportion to about 27 volts.

Hello Kelly:

I have to ask, why are you still interested in Fluorescent lamps - they are effectively obsolete here in the US!

They are  being replaced with LED based lamps - in 2 ft, 4 ft and 8 ft sizes .

I buy my replacement 2 ft or 4 ft LED's (for 120 volts) for home use, from the following manufacturer www.eledlights.com

Peter Brooks

Palm Bay Florida USA

Hi Peter my reasons for interest in flurescent lamps is partly curiosity and because I really like them I am hoping to get hold of an 8 foot fitting eventually need to have a word with a tame electrician Lol. I hate LED lighting partly because twice I was shouted out by 2 different eco nuts one at my old job and one was a relative they both really were nasty  about me using filament bulbs so I use flurescent and filament lighting as much as I can. That's the story more or less. Wish I was in florida now  its so cold here at the moment il leave you with that thought!

Kelly Marie Angel, do you have a problem with LEDs for new installations.

I do not, but I have difficulty with throwing out an existing flory for want of a starter.

I suppose that filament lamps are a no-no, but why not replace on failure rather than earlier?

Hello Kelly:

What makes you think it doesn't get cold in Florida?

This morning we hit a low of 41 degrees F. We have the central heat (we have a heat pump) on in the house (set to 75 degrees F). 

Peter Brooks

Palm Bay Florida USA