I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet? Though I don't like the light from
my head torch or even any that I've put into lamps

--
AnthonyL

Why do scientists need to BELIEVE in anything?

On 13/05/2020 12:47, AnthonyL wrote:
I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet? Though I don't like the light from
my head torch or even any that I've put into lamps



https://www.screwfix.com/p/27862



--
Adam

On Wed, 13 May 2020 16:59:59 +0100, ARW
wrote:

On 13/05/2020 12:47, AnthonyL wrote:
I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet? Though I don't like the light from
my head torch or even any that I've put into lamps



https://www.screwfix.com/p/27862


Page not found.

But assuming you mean:

https://www.screwfix.com/p/sylvania-...6w-212mm/27862

I'd first like to check whether the torch on the whole works and
putting a new tube in is likely to give me light.





--
AnthonyL

Why do scientists need to BELIEVE in anything?

AnthonyL wrote:

ARW wrote

https://www.screwfix.com/p/27862

Page not found.
But assuming you mean:
https://www.screwfix.com/p/sylvania-...6w-212mm/27862
With screwfix URLs you can shorten, or replace the "descriptive junk"
between the /p/ and the /99999 code, but you can't remove it entirely

https://www.screwfix.com/p/any-old-bollox/27862 ... works

https://www.screwfix.com/p/p/27862 ... works

https://screwfix.com/p/p/27862 ... works

On 14/05/2020 13:41, Andy Burns wrote:
AnthonyL wrote:

ARW wrote

https://www.screwfix.com/p/27862

Page not found. But assuming you mean:
https://www.screwfix.com/p/sylvania-...6w-212mm/27862

With screwfix URLs you can shorten, or replace the "descriptive junk"
between the /p/ and the /99999 code, but you can't remove it entirely

https://www.screwfix.com/p/any-old-bollox/27862 ... works

https://www.screwfix.com/p/p/27862 ... works

https://screwfix.com/p/p/27862 ... works

Useful tip thanks. It's the links that start with Google, then all the
search terms, and have the target buried inside it somewhere that
irritate me.

newshound wrote:

It's the links that start with Google, then all the search terms, and
have the target buried inside it somewhere that irritate me.

Usually when google has returned a PDF? e.g.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=33&ved=2ahU KEwjvoL2H6rXpAhVxtXEKHWadA8gQFjAgegQIDhAB&url=http s%3A%2F%2Fwww.ukri.org%2Ffiles%2Fresearch-questions-for-covid-19%2F&usg=AOvVaw1kxkOJCnN-ztVWR60op22I

you can pick the bones out of it by hand, and translate the various html
escape codes, but I tend to click the link, that follows google's
redirection, then in firefox's download list, right click and copy
location, which gives e.g.

https://www.ukri.org/files/research-questions-for-covid-19

On 14/05/2020 12:36, AnthonyL wrote:
On Wed, 13 May 2020 16:59:59 +0100, ARW
wrote:

On 13/05/2020 12:47, AnthonyL wrote:
I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet? Though I don't like the light from
my head torch or even any that I've put into lamps



https://www.screwfix.com/p/27862


Page not found.

But assuming you mean:

https://www.screwfix.com/p/sylvania-...6w-212mm/27862

I'd first like to check whether the torch on the whole works and
putting a new tube in is likely to give me light.






Sorry about that. I should have checked the link:-(

At work we test lamps with the apprentices cattle prods

https://www.youtube.com/watch?time_c...ature=emb_logo

As pointed out by others trying the lamp the other way around is all you
can probably try.

--
Adam

AnthonyL wrote:
I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet? Though I don't like the light from
my head torch or even any that I've put into lamps


Tubes work best with sine wave (AC) drive. In this example
web page, the "working" voltage listed for the tube is 70V.

https://www.electroschematics.com/fl...t-lamp-driver/

"After start, the voltage collapses from several hundred volts
to the operating voltage, which is ca 70V for an 8W rod."

It's highly likely there is an inverter of some sort, inside
the plastic housing. And with any luck, glued plastic pieces
to keep you out.

"Pure flyback single-transistor inverter, makes voltage spikes
in the kilovolt range in idling condition, so that the lamp
will start. Disadvantage: One filament evaporates and blackens
the lamp, makes it electrically unsymmetric and shortens the lifetime."

Paul

Paul formulated on Wednesday :
"Pure flyback single-transistor inverter, makes voltage spikes
in the kilovolt range in idling condition, so that the lamp
will start. Disadvantage: One filament evaporates and blackens
the lamp, makes it electrically unsymmetric and shortens the lifetime."

Basically a pulsing DC. The fix for the the black at one end, was to
simply take the tube out and reinsert it swapped end for end.

On Wed, 13 May 2020 13:48:11 -0400, Paul
wrote:

AnthonyL wrote:
I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet? Though I don't like the light from
my head torch or even any that I've put into lamps


Tubes work best with sine wave (AC) drive. In this example
web page, the "working" voltage listed for the tube is 70V.

https://www.electroschematics.com/fl...t-lamp-driver/

"After start, the voltage collapses from several hundred volts
to the operating voltage, which is ca 70V for an 8W rod."

It's highly likely there is an inverter of some sort, inside
the plastic housing. And with any luck, glued plastic pieces
to keep you out.

"Pure flyback single-transistor inverter, makes voltage spikes
in the kilovolt range in idling condition, so that the lamp
will start. Disadvantage: One filament evaporates and blackens
the lamp, makes it electrically unsymmetric and shortens the lifetime."



Well I can get to the connections that the tube fits in. So with
power connected I should get an AC voltage reading with my
multi-meter?


--
AnthonyL

Why do scientists need to BELIEVE in anything?

AnthonyL wrote:
On Wed, 13 May 2020 13:48:11 -0400, Paul
wrote:

AnthonyL wrote:
I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet? Though I don't like the light from
my head torch or even any that I've put into lamps

Tubes work best with sine wave (AC) drive. In this example
web page, the "working" voltage listed for the tube is 70V.

https://www.electroschematics.com/fl...t-lamp-driver/

"After start, the voltage collapses from several hundred volts
to the operating voltage, which is ca 70V for an 8W rod."

It's highly likely there is an inverter of some sort, inside
the plastic housing. And with any luck, glued plastic pieces
to keep you out.

"Pure flyback single-transistor inverter, makes voltage spikes
in the kilovolt range in idling condition, so that the lamp
will start. Disadvantage: One filament evaporates and blackens
the lamp, makes it electrically unsymmetric and shortens the lifetime."



Well I can get to the connections that the tube fits in. So with
power connected I should get an AC voltage reading with my
multi-meter?

Are you going to make the measurement with a load, or with no load ?

First of all, this web page is *not* about a Johnlite 6W fluorescent lantern.
What it does show though, is the "ignite/burn" curve. If the tube runs
at 70V, it ignites at 200V.

https://www.edn.com/electronic-balla...ower-supplies/

If the tube did not ignite, the voltage could rise above 200V.

My objective here, is to prevent two things from happening.

1) Avoid having AnthonyL zapped by the voltage across the tube socket pair.
And thrown across the room. Now, it's not going to do that, as long
as the frequency remains high. At 20KHz, you might not feel it, but
it might cause a flesh burn if you don't rapidly remove your hand.
At 100KHz, it would definitely be a "skin effect" thing, rather than
hitting a nerve. If the frequency were to drop (due to loading caused
by human dead short across socket), then that aggravates the shock hazard.

2) Prevent multimeter AC 1000V range from blowing out, taking out
measurement chip. I've only seen one meter blown out that way,
a Fluke with about 2kV across it. That was in a physics lab, a
Xenon flash tube driver, which a masters student destroyed by
being not clever. When I saw him reach for the meter, I thought
to myself "he's not that stupid, he's a genius". Oh, well, never
assume anything.

I don't want you to get hurt fooling with this stuff.

If the filaments are not hooked up (circuit uses two pins of
the four pins total on the tube), then it's not using the filaments
to heat the mercury, and it's relying on a little extra voltage
to establish the initial plasma. You could place a resistor in
place of the tube, using the two pins that are connected.

What value should you use ? Is it a 820 ohms 6 watt
power resistor ? Is it a 1 megohm resistor ? The circuit has a high Q,
and the trick is intuitively picking the right load to prevent
runaway behavior. 70V 6W would be 820 ohms (V^2/R = P = 6W = 70v*70v/820 ohms.

That's a rather obscure value for the parts cabinet, and by the time
you were done, you could likely purchase a replacement tube instead :-)
And measure with that present. Or, don't even bother to measure
and just use it. I have power resistors, but they're in the 1 ohm
to 10 ohm range or so.

I have one of these Johnlite lamps, but I don't know where it's got to.
It's not on my junkroom list, which means I have no hints
to work with. It's one of the black plastic ones.

Paul

On Wednesday, 13 May 2020 12:47:09 UTC+1, AnthonyL wrote:

I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

So THAT'S where it went. If you ever come round maybe you could bring it back


The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

same as the battery, 9v. Polarity matters for the fl tube, and probably for the flasher. You haven't just given it the wrong polarity?

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

Usually it's easiest to replace the whole piece of spring wire rather than splice partial bits. So however it's fixed on now. IME battery holder springs don't solder well. Some battery holders rivet the springs, and the rivets do solder.


2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

close to 99% of fl tube failures are filament burnout. Check continuity between the 2 pins at each end. If either end is o/c it's a deadun - though there are ballasts that can get such tubes going.

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet?

Oh yes, much more efficient, longer lived, better efficacy, more reliable. But those old things are still cool. Before you shuffle this mortal coil they'll be collectible retro.

Though I don't like the light from
my head torch or even any that I've put into lamps

As Paul pointed out, cheapskate ballasts blacken & kill one end of the tube, so put it back in the other way round to increase its life.


NT

As Paul pointed out, cheapskate ballasts blacken & kill one end of the
tube, so put it back in the other way round to increase its life.


NT


Aldi - Lidl - LED - surely the way to go - those fluorescents were never
very good.

has brought this to us :
close to 99% of fl tube failures are filament burnout. Check continuity
between the 2 pins at each end. If either end is o/c it's a deadun - though
there are ballasts that can get such tubes going.

The end filaments are not used as heaters when an invertor is involved,
instead they rely upon creating a high voltage / high impedance between
the ends, which is enough to get them to strike.

On Wed, 13 May 2020 13:17:15 -0700 (PDT), wrote:

On Wednesday, 13 May 2020 12:47:09 UTC+1, AnthonyL wrote:

I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

So THAT'S where it went. If you ever come round maybe you could bring it back


The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

same as the battery, 9v. Polarity matters for the fl tube, and probably for the flasher. You haven't just given it the wrong polarity?



At this stage I don't know, I've assume centre = +ve but there is no
indication on the socket. As also I'm assuming 9v because that is 6 x
"D" at 1.5v ea.

I guess I'll lose nothing if the fluorescent tube isn't in by rigging
up a reverse polarity connection or clip a PP3 in where the 'D' cells
go and see which way round things are at a bulb.


--
AnthonyL

Why do scientists need to BELIEVE in anything?

On 14/05/2020 12:41:05, AnthonyL wrote:
On Wed, 13 May 2020 13:17:15 -0700 (PDT), wrote:

On Wednesday, 13 May 2020 12:47:09 UTC+1, AnthonyL wrote:

I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

So THAT'S where it went. If you ever come round maybe you could bring it back


The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

same as the battery, 9v. Polarity matters for the fl tube, and probably for the flasher. You haven't just given it the wrong polarity?



At this stage I don't know, I've assume centre = +ve but there is no
indication on the socket. As also I'm assuming 9v because that is 6 x
"D" at 1.5v ea.

I guess I'll lose nothing if the fluorescent tube isn't in by rigging
up a reverse polarity connection or clip a PP3 in where the 'D' cells
go and see which way round things are at a bulb.

There will be an inverter to power the tube. Reverse polarity might well
damage the inverter.

On 14/05/2020 12:41, AnthonyL wrote:
On Wed, 13 May 2020 13:17:15 -0700 (PDT), wrote:

On Wednesday, 13 May 2020 12:47:09 UTC+1, AnthonyL wrote:

I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

So THAT'S where it went. If you ever come round maybe you could bring it back


The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

same as the battery, 9v. Polarity matters for the fl tube, and probably for the flasher. You haven't just given it the wrong polarity?



At this stage I don't know, I've assume centre = +ve but there is no
indication on the socket. As also I'm assuming 9v because that is 6 x
"D" at 1.5v ea.

I guess I'll lose nothing if the fluorescent tube isn't in by rigging
up a reverse polarity connection or clip a PP3 in where the 'D' cells
go and see which way round things are at a bulb.

A filament bulb won't care at all which way round the battery is but the
inverter for the fluoro tube will probably emit its magic smoke if you
connect the battery the wrong way around.

Usually you can work out the polarity in the end with the conical coiled
spring is negative and the end with the small rigid centre is positive.

These days it might be altogether simpler to buy a modern power LED
torch and throw the old thing away. It might even be cheaper than buying
a replacement mini fluoro tube. It will almost certainly be brighter.


--
Regards,
Martin Brown

On Thursday, 14 May 2020 22:47:49 UTC+1, Martin Brown wrote:
On 14/05/2020 12:41, AnthonyL wrote:
On Wed, 13 May 2020 13:17:15 -0700 (PDT), tabbypurr wrote:
On Wednesday, 13 May 2020 12:47:09 UTC+1, AnthonyL wrote:

I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

So THAT'S where it went. If you ever come round maybe you could bring it back


The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

same as the battery, 9v. Polarity matters for the fl tube, and probably for the flasher. You haven't just given it the wrong polarity?



At this stage I don't know, I've assume centre = +ve but there is no
indication on the socket. As also I'm assuming 9v because that is 6 x
"D" at 1.5v ea.

I guess I'll lose nothing if the fluorescent tube isn't in by rigging
up a reverse polarity connection or clip a PP3 in where the 'D' cells
go and see which way round things are at a bulb.

A filament bulb won't care at all which way round the battery is but the
inverter for the fluoro tube will probably emit its magic smoke if you
connect the battery the wrong way around.

Usually you can work out the polarity in the end with the conical coiled
spring is negative and the end with the small rigid centre is positive.

one pole of the dc input will be connected to one pole of the battery. Test with a multimeter - or torch.

These days it might be altogether simpler to buy a modern power LED
torch and throw the old thing away. It might even be cheaper than buying
a replacement mini fluoro tube. It will almost certainly be brighter.

Sure, I'd still keep the old one though. But I'd not use the tube for long periods.


NT

On Thu, 14 May 2020 16:37:00 -0700 (PDT), wrote:

On Thursday, 14 May 2020 22:47:49 UTC+1, Martin Brown wrote:
On 14/05/2020 12:41, AnthonyL wrote:
On Wed, 13 May 2020 13:17:15 -0700 (PDT), tabbypurr wrote:
On Wednesday, 13 May 2020 12:47:09 UTC+1, AnthonyL wrote:

I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

So THAT'S where it went. If you ever come round maybe you could bring it back


The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

same as the battery, 9v. Polarity matters for the fl tube, and probably for the flasher. You haven't just given it the wrong polarity?



At this stage I don't know, I've assume centre = +ve but there is no
indication on the socket. As also I'm assuming 9v because that is 6 x
"D" at 1.5v ea.

I guess I'll lose nothing if the fluorescent tube isn't in by rigging
up a reverse polarity connection or clip a PP3 in where the 'D' cells
go and see which way round things are at a bulb.

A filament bulb won't care at all which way round the battery is but the
inverter for the fluoro tube will probably emit its magic smoke if you
connect the battery the wrong way around.

Usually you can work out the polarity in the end with the conical coiled
spring is negative and the end with the small rigid centre is positive.

one pole of the dc input will be connected to one pole of the battery. Test with a multimeter - or torch.

These days it might be altogether simpler to buy a modern power LED
torch and throw the old thing away. It might even be cheaper than buying
a replacement mini fluoro tube. It will almost certainly be brighter.

Sure, I'd still keep the old one though. But I'd not use the tube for long periods.


Are you sure you want it back?

--
AnthonyL

Why do scientists need to BELIEVE in anything?

On Thu, 14 May 2020 22:47:44 +0100, Martin Brown
wrote:

On 14/05/2020 12:41, AnthonyL wrote:
On Wed, 13 May 2020 13:17:15 -0700 (PDT), wrote:

On Wednesday, 13 May 2020 12:47:09 UTC+1, AnthonyL wrote:

I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

So THAT'S where it went. If you ever come round maybe you could bring it back


The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

same as the battery, 9v. Polarity matters for the fl tube, and probably for the flasher. You haven't just given it the wrong polarity?



At this stage I don't know, I've assume centre = +ve but there is no
indication on the socket. As also I'm assuming 9v because that is 6 x
"D" at 1.5v ea.

I guess I'll lose nothing if the fluorescent tube isn't in by rigging
up a reverse polarity connection or clip a PP3 in where the 'D' cells
go and see which way round things are at a bulb.

A filament bulb won't care at all which way round the battery is but the
inverter for the fluoro tube will probably emit its magic smoke if you
connect the battery the wrong way around.

Usually you can work out the polarity in the end with the conical coiled
spring is negative and the end with the small rigid centre is positive.


I know which polarity the batteries would go in but I don't have 6 x
"D". However I do have a 9v power supply but which fits but I don't
know whether it is centre +ve or -ve as there is no marking on the
torch. I thought if I put a PP3 onto where the "D" cells terminate
I'd be able to reverse check the polarity of the power supply socket.

These days it might be altogether simpler to buy a modern power LED
torch and throw the old thing away. It might even be cheaper than buying
a replacement mini fluoro tube. It will almost certainly be brighter.


I've been watching too much Repair Shop!


--
AnthonyL

Why do scientists need to BELIEVE in anything?

On 13/05/2020 12:47, AnthonyL wrote:
I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet? Though I don't like the light from
my head torch or even any that I've put into lamps

TBH refurbishing battery connections is a PITA, and my experience of
such lights is that the inverters are not very good. A modern LED torch
will certainly give you more lumens per battery.