Battery powered fluorescent tube lights - UK Vintage Radio Repair and Restoration Discussion Forum

IanNVJ35 · 25th Nov 2016, 12:15 pm

For the garage I really wanted a fluorescent tube light to help me see what I am looking for rather than a beam. So off I set to look for one - and met up with junk that looked a waste of money. So on eBay I found EXACTLY what I wanted - for £2.70 - plus it was vintage!

and it arrived this morning. Well, before just throwing batteries in there I ran it on my power supply to see what it was about. At 12 Volts it draws 0.35 Amps, and lowering the voltage dims the tube and lowers the current, higher (13 Volts) brightens the tube and takes more current. The circuit involved looks like a transformer, a 'regulator' looking item, two resistors, a diode, a white rectangular item, variable resistor and a small ceramic capacitor (all this looked at through a tiny hole). I honestly don't know much about this technology so I thought I would ask. If the tube gets brighter with more voltage does that mean the tube is running below optimum? I did note that the circuit runs quite warm, makes for a warm plastic smell so not sure if more voltage would help make things last longer or just burn things up.

Thanks for any input - always good to know more!

emeritus · 25th Nov 2016, 1:34 pm

I don't know anything about this model, but when we had a motor caravan that was fitted with 12V fluorescents, I used to periodically reverse the tubes when the illumination dropped off after a long period of use. Some lamp circuits produce a voltage that has a DC component that can affect a tube's efficiency. Where fluorescents were used on DC supplies, before the advent of inverters it was often the practice to control them with special double-pole switches that reversed the polarity each time the lamp was operated.

broadgage · 25th Nov 2016, 1:45 pm

The "regulator looking item" is probably a small power transistor.

I would think twice about regularly running this item on 12 volts, and would avoid 13 volts.
The intended power source is 8 dry cells each nominally 1.5 volt. The voltage drops significantly under load and I would expect the actual running voltage to be about 9.5 volts to 10 volts.

IanNVJ35 · 25th Nov 2016, 2:37 pm

Thanks for the input. I am intending to fit an external regulator to allow the use of rechargeable AA batteries in D holders so knowing what voltage to set it to is a real help. If I set to 10 Volts, that should be about right then?

broadgage · 25th Nov 2016, 5:37 pm

Yes 10 volts should be fine. It is not critical as the actual voltage of the dry batteries would have varied a fair bit, from perhaps 11 volts when new down to about 7 volts just before replacement.

Some similar lights came with a lead for connection to a 12 volt vehicle battery, these tended to either rely on the resistance of the long thin lead to drop a couple of volts, or they had a dropper resistance in series with the lead.

A similar light that I used to have used 9 cells rather than 8 cells, presumably so as to give a better approximation to the same voltage from a car battery or the internal battery.

25th Nov 2016, 7:23 pm

I wouldn't bother with a regulator, seven cells in series will be 10.5 V nominal and drop a bit during use.

IanNVJ35 · 25th Nov 2016, 7:30 pm

This light is 8 cells, but I worked out that 8 NiMh D cells would give me 9.6 volts so that may be another way.

broadgage · 25th Nov 2016, 8:23 pm

For use from internal batteries I see no need for a regulator, 8 cells as originally intended will be fine. 8 disposable cells will be 12 volts nominal but drop to about 9.5 or 10 volts whilst on load.
8 rechargeable cells will be about 9.6 volts which will hardly alter on load and be just as suitable.

If using an external supply, I would use either a 10 volt supply, preferably regulated, or if easier use a 12 volt supply and a dropper resistance to produce about 9.5 to 10 volts.

The voltage of the originally intended 8 dry cells would have varied a fair bit, so no real accuracy is needed, but a full 12 volts continually is probably a bit much.

IanNVJ35 · 27th Nov 2016, 10:06 pm

Just an update. I picked up some D size rechargeable batteries from Chas Ohlson (3000mAh) and fitted them. The light worked with them very well. The only thing that really needed doing was spraying the white reflector with gloss white acrylic paint as it was somewhat yellowed with age. Now the lamp really is a useful utility light and I'll get plenty of use our of it this winter.

25th Nov 2016, 12:15 pm	#1
IanNVJ35 Heptode Join Date: Mar 2010 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 846	Battery powered fluorescent tube lights For the garage I really wanted a fluorescent tube light to help me see what I am looking for rather than a beam. So off I set to look for one - and met up with junk that looked a waste of money. So on eBay I found EXACTLY what I wanted - for £2.70 - plus it was vintage! and it arrived this morning. Well, before just throwing batteries in there I ran it on my power supply to see what it was about. At 12 Volts it draws 0.35 Amps, and lowering the voltage dims the tube and lowers the current, higher (13 Volts) brightens the tube and takes more current. The circuit involved looks like a transformer, a 'regulator' looking item, two resistors, a diode, a white rectangular item, variable resistor and a small ceramic capacitor (all this looked at through a tiny hole). I honestly don't know much about this technology so I thought I would ask. If the tube gets brighter with more voltage does that mean the tube is running below optimum? I did note that the circuit runs quite warm, makes for a warm plastic smell so not sure if more voltage would help make things last longer or just burn things up. Thanks for any input - always good to know more! Attached Thumbnails Last edited by AC/HL; 25th Nov 2016 at 1:39 pm. Reason: Image uploaded

25th Nov 2016, 1:34 pm	#2
emeritus Dekatron Join Date: Jan 2012 Location: Brentwood, Essex, UK. Posts: 5,339	Re: Battery powered fluorescent tube lights I don't know anything about this model, but when we had a motor caravan that was fitted with 12V fluorescents, I used to periodically reverse the tubes when the illumination dropped off after a long period of use. Some lamp circuits produce a voltage that has a DC component that can affect a tube's efficiency. Where fluorescents were used on DC supplies, before the advent of inverters it was often the practice to control them with special double-pole switches that reversed the polarity each time the lamp was operated.

25th Nov 2016, 1:45 pm	#3
broadgage Nonode Join Date: Jan 2010 Location: North Somerset, UK. Posts: 2,129	Re: Battery powered fluorescent tube lights The "regulator looking item" is probably a small power transistor. I would think twice about regularly running this item on 12 volts, and would avoid 13 volts. The intended power source is 8 dry cells each nominally 1.5 volt. The voltage drops significantly under load and I would expect the actual running voltage to be about 9.5 volts to 10 volts.

25th Nov 2016, 2:37 pm	#4
IanNVJ35 Heptode Join Date: Mar 2010 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 846	Re: Battery powered fluorescent tube lights Thanks for the input. I am intending to fit an external regulator to allow the use of rechargeable AA batteries in D holders so knowing what voltage to set it to is a real help. If I set to 10 Volts, that should be about right then?

25th Nov 2016, 5:37 pm	#5
broadgage Nonode Join Date: Jan 2010 Location: North Somerset, UK. Posts: 2,129	Re: Battery powered fluorescent tube lights Yes 10 volts should be fine. It is not critical as the actual voltage of the dry batteries would have varied a fair bit, from perhaps 11 volts when new down to about 7 volts just before replacement. Some similar lights came with a lead for connection to a 12 volt vehicle battery, these tended to either rely on the resistance of the long thin lead to drop a couple of volts, or they had a dropper resistance in series with the lead. A similar light that I used to have used 9 cells rather than 8 cells, presumably so as to give a better approximation to the same voltage from a car battery or the internal battery.

25th Nov 2016, 7:23 pm	#6
Guest Guest Posts: n/a	Re: Battery powered fluorescent tube lights I wouldn't bother with a regulator, seven cells in series will be 10.5 V nominal and drop a bit during use.

25th Nov 2016, 7:30 pm	#7
IanNVJ35 Heptode Join Date: Mar 2010 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 846	Re: Battery powered fluorescent tube lights This light is 8 cells, but I worked out that 8 NiMh D cells would give me 9.6 volts so that may be another way.

25th Nov 2016, 8:23 pm	#8
broadgage Nonode Join Date: Jan 2010 Location: North Somerset, UK. Posts: 2,129	Re: Battery powered fluorescent tube lights For use from internal batteries I see no need for a regulator, 8 cells as originally intended will be fine. 8 disposable cells will be 12 volts nominal but drop to about 9.5 or 10 volts whilst on load. 8 rechargeable cells will be about 9.6 volts which will hardly alter on load and be just as suitable. If using an external supply, I would use either a 10 volt supply, preferably regulated, or if easier use a 12 volt supply and a dropper resistance to produce about 9.5 to 10 volts. The voltage of the originally intended 8 dry cells would have varied a fair bit, so no real accuracy is needed, but a full 12 volts continually is probably a bit much.

27th Nov 2016, 10:06 pm	#9
IanNVJ35 Heptode Join Date: Mar 2010 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 846	Re: Battery powered fluorescent tube lights Just an update. I picked up some D size rechargeable batteries from Chas Ohlson (3000mAh) and fitted them. The light worked with them very well. The only thing that really needed doing was spraying the white reflector with gloss white acrylic paint as it was somewhat yellowed with age. Now the lamp really is a useful utility light and I'll get plenty of use our of it this winter.