Driving miniature TL flou

[Richard]

I bought a cheap flourescent luminair. Works of 12 VDC 500mA.

I took it apart because I thought the lamp inside is about the right size
for a project. Ballast is electronic on a small PCB, only a few descrete
components. Obviously the ballast is cheap to make.

Inside is an unbranded T5 lamp of 8W. It's 288mm long so it is a mini TL
lamp. Two pins on each end.

Looking at Philips technical site I see that the recommended ballast for
this kind of Philips lamp/lamp would be type BPL 02W. This ballast is a
simple inductor. It's compactish, 85mm x 39mm x 28mm. Wiring is standard
when using a choke and a starter.

But, the electronic ballast in this luminaire does not employ the heaters.
Pins at both end are joined together.

I suppose that whether employing the cheap electronic ballast or the choke,
the lamp gives the same light output. True? But for economy, I guess one
would always go with the proprietry electronic ballast. Although mains
working would require a step doen transformer. So, cost savings would
not materilise - perhaps.

Not sure about any differences in lamp protection and safety.

I just get to wondering when I come across this kind of thing why anyone
would select the choke ballast.

 

[Richard]

I bought a cheap flourescent luminair. Works of 12 VDC 500mA.

I took it apart because I thought the lamp inside is about the right size
for a project. Ballast is electronic on a small PCB, only a few descrete
components. Obviously the ballast is cheap to make.

Inside is an unbranded T5 lamp of 8W. It's 288mm long so it is a mini TL
lamp. Two pins on each end.

Looking at Philips technical site I see that the recommended ballast for
this kind of Philips lamp/lamp would be type BPL 02W. This ballast is a
simple inductor. It's compactish, 85mm x 39mm x 28mm. Wiring is standard
when using a choke and a starter.

But, the electronic ballast in this luminaire does not employ the heaters.
Pins at both end are joined together.

I suppose that whether employing the cheap electronic ballast or the
choke,
the lamp gives the same light output. True? But for economy, I guess one
would always go with the proprietry electronic ballast. Although mains
working would require a step doen transformer. So, cost savings would
not materilise - perhaps.

Not sure about any differences in lamp protection and safety.

I just get to wondering when I come across this kind of thing why anyone
would select the choke ballast.

Although it occurs to me that I bought that luminaire that's run off 12V. I
think I could be mixing apples and oranges a bit here.

 

[TKM]

I bought a cheap fluorescent luminair. Works of 12 VDC 500mA.

I took it apart because I thought the lamp inside is about the right size
for a project. Ballast is electronic on a small PCB, only a few descrete
components. Obviously the ballast is cheap to make.

Inside is an unbranded T5 lamp of 8W. It's 288mm long so it is a mini TL
lamp. Two pins on each end.

Looking at Philips technical site I see that the recommended ballast for
this kind of Philips lamp/lamp would be type BPL 02W. This ballast is a
simple inductor. It's compactish, 85mm x 39mm x 28mm. Wiring is standard
when using a choke and a starter.

But, the electronic ballast in this luminaire does not employ the heaters.
Pins at both end are joined together.

I suppose that whether employing the cheap electronic ballast or the
choke,
the lamp gives the same light output. True? But for economy, I guess one
would always go with the proprietry electronic ballast. Although mains
working would require a step doen transformer. So, cost savings would
not materilise - perhaps.

Not sure about any differences in lamp protection and safety.

I just get to wondering when I come across this kind of thing why anyone
would select the choke ballast.

Fluorescent lamp ballasts have two main functions (1) start the lamp (2)
control the current through the lamp. A choke ballast works just fine if
there's already enough voltage available from the supply line for starting.

When the lamp pins are shorted together, the starting mode is likely to be
what's called "instant start". That starting mode uses the available
voltage to ionize the gas in the lamp. When the current starts flowing, the
lamp cathodes get hot and the lamp current stabilizes at some value
determined by the external ballast circuit (choke or electronic current
limiter).

In your situation since the fixture is designed to be powered by 12 volts,
there's an inverter someplace that transforms the 12 volts dc to high
voltage and, probably, high frequency ac.

The key factors to determine if you're building your own ballast are the
lamp's current rating, and starting voltage.

Terry McGowan

 

[Andrew Gabriel]

I bought a cheap flourescent luminair. Works of 12 VDC 500mA.

I took it apart because I thought the lamp inside is about the right size
for a project. Ballast is electronic on a small PCB, only a few descrete
components. Obviously the ballast is cheap to make.

Inside is an unbranded T5 lamp of 8W. It's 288mm long so it is a mini TL
lamp. Two pins on each end.

Looking at Philips technical site I see that the recommended ballast for
this kind of Philips lamp/lamp would be type BPL 02W. This ballast is a
simple inductor. It's compactish, 85mm x 39mm x 28mm. Wiring is standard
when using a choke and a starter.

But, the electronic ballast in this luminaire does not employ the heaters.
Pins at both end are joined together.

Many of those cheap battery inverters don't drive the tube
very well. The lack of preheating will result in fewer starts,
but worse, they often significantly under-run the tube, meaning
the filaments don't get as hot as they should, ant this also
reduces tube live. Often doesn't matter with battery lights as
they aren't operated for that long (battery replacement price
and frequency would become a significant issue).

I suppose that whether employing the cheap electronic ballast or the choke,
the lamp gives the same light output. True? But for economy, I guess one

As I said, many of those cheap battery inverters significantly
under-run the tube, and get short tube life as a result.

would always go with the proprietry electronic ballast. Although mains
working would require a step doen transformer. So, cost savings would
not materilise - perhaps.

Not sure about any differences in lamp protection and safety.

I just get to wondering when I come across this kind of thing why anyone
would select the choke ballast.

They are cheap. It's also worth pointing out that the 4/6/8W T5
tubes don't work very well on 240V series ballasts with glow
starters. Two things are non-optimal - the 240V mains voltage
can sometimes instant-start them before the filaments get heated up,
but if it doesn't, it can take quite a bit of flashing to get them
started. Glow-start works well with all tubes from 24" upwards
on 240V, but not with the very short tubes.

I would suggest you get a Philips MF-Matchbox 109 ballast. This
is a mains electronic ballast for this tube. It comes in two
types, Blue which is instant start, and Red which is preheat.
Preheat will give longer tube life in the case of frequently
switching on and off. Instant start may be preferable where
you don't want a second or so starting delay and either don't
switch on and off frequently or don't care about the reduction
in tube life. Both types require 4 connections to the tube and
power the filaments (unlike US instant-start circuits). Each
type is available in 2 shapes -- a matchbox, or a longer thinner
box (more suitable for going into a thin T5 fitting), and both
these are also available as just the bare circuit board too.

RS do the Blue cased ones for around £7 (+ VAT/P&P):
http://uk.rs-online.com/web/search/...od=searchProducts&searchTerm=philips+matchbox

The other thing you might be interested in is making your own
ballast from an old CFL. There are some notes here:

http://www.cucumber.demon.co.uk/lights/diy/

The following shows the Philips matchbox ballast retrofitted
into a light and driving a 10W 2D lamp

http://www.cucumber.demon.co.uk/lights/diy2/

 

[[email protected]]

I bought a cheap flourescent luminair. Works of 12 VDC 500mA.

There are some schematics for inverters designed to run small
fluorescent tubes off of low-voltage DC at
http://www.repairfaq.org/sam/samschem.htm#schamt
that you might find interesting.

Matt Roberds

 

[Richard]

Many of those cheap battery inverters don't drive the tube
very well. The lack of preheating will result in fewer starts,
but worse, they often significantly under-run the tube, meaning
the filaments don't get as hot as they should, ant this also
reduces tube live. Often doesn't matter with battery lights as
they aren't operated for that long (battery replacement price
and frequency would become a significant issue).


As I said, many of those cheap battery inverters significantly
under-run the tube, and get short tube life as a result.


They are cheap. It's also worth pointing out that the 4/6/8W T5
tubes don't work very well on 240V series ballasts with glow
starters. Two things are non-optimal - the 240V mains voltage
can sometimes instant-start them before the filaments get heated up,
but if it doesn't, it can take quite a bit of flashing to get them
started. Glow-start works well with all tubes from 24" upwards
on 240V, but not with the very short tubes.

I would suggest you get a Philips MF-Matchbox 109 ballast. This
is a mains electronic ballast for this tube. It comes in two
types, Blue which is instant start, and Red which is preheat.
Preheat will give longer tube life in the case of frequently
switching on and off. Instant start may be preferable where
you don't want a second or so starting delay and either don't
switch on and off frequently or don't care about the reduction
in tube life. Both types require 4 connections to the tube and
power the filaments (unlike US instant-start circuits). Each
type is available in 2 shapes -- a matchbox, or a longer thinner
box (more suitable for going into a thin T5 fitting), and both
these are also available as just the bare circuit board too.

RS do the Blue cased ones for around £7 (+ VAT/P&P):
http://uk.rs-online.com/web/search/...od=searchProducts&searchTerm=philips+matchbox

The other thing you might be interested in is making your own
ballast from an old CFL. There are some notes here:

http://www.cucumber.demon.co.uk/lights/diy/

The following shows the Philips matchbox ballast retrofitted
into a light and driving a 10W 2D lamp

http://www.cucumber.demon.co.uk/lights/diy2/

Lets say I'm making a table lamp using a miniature T5, something like an 8W
or 13W lamp.

There are at least two ways:

1 You employ a 12V (say) adaptor, and that plugs into the table lamp. Of
course the simple inverter inside the table lamp is very small and very
cheap.

2 Another way is to feed the lamp directly with AC mains using either
something like a Philips Matchbox ballast, or a simple small choke ballast.

Because I've got in my head the notion that option 2 is the more expensive
option, because of expensive ballasts I'm always thinking that option 1 is
better.

But, I'm not sure option 2 needs to be as expensive as I think it is. I
think this proves the point:

http://www.dealec.co.uk/acatalog/erc_compact_fluorescent_ballasts_mec75.html

 

[Andrew Gabriel]

Lets say I'm making a table lamp using a miniature T5, something like an 8W
or 13W lamp.

There are at least two ways:

1 You employ a 12V (say) adaptor, and that plugs into the table lamp. Of
course the simple inverter inside the table lamp is very small and very
cheap.

2 Another way is to feed the lamp directly with AC mains using either
something like a Philips Matchbox ballast, or a simple small choke ballast.

Because I've got in my head the notion that option 2 is the more expensive
option, because of expensive ballasts I'm always thinking that option 1 is
better.

But, I'm not sure option 2 needs to be as expensive as I think it is. I
think this proves the point:

http://www.dealec.co.uk/acatalog/erc_compact_fluorescent_ballasts_mec75.html

You also need a glow starter and socket. Like I said, they don't
work too well with the 4/6/8W tubes. You could try a wire-ended
or plug-in electronic fluoractor based starter such as the
Pulsestarter EFS 600. I've never tried one with the low power
tubes, although the one I have here says 4W - 125W and it may
work better than a glow starter.

I would however go for the electronic ballast.

 

[Richard]

Sorry to be a bit late to this discussion.

As others have stated, the electronic ballast operates this
lamp in what we in the US would call instant start mode.


Not true. Fluorescent lamps give more light output per watt
of power input when operated at frequencies above about
10kHz. If the electronic ballast is of reasonable quality,
then it will give higher overall efficacy than the series
choke system.


No again. As I think Terry has pointed out, as long as the
mains have enough voltage, the series choke takes care of
the "excess" voltage.


They were, and may still be, lower cost and that are also
the basic "standard" ballast for this type of lamp.

I think probably with a F8 T5 lamp, it's very often going to be used in a
portable situation.

In that context it's likely to be run of a 12V/24V DC supply. That means use
of a small, inexpensive flourescent inverter.

Some inveters may not drive the lamp fully. That's what I hear.

Where the supply is 240v AC, the basic "standard" ballast is likely. Which
can also be low cost.

Just what I think I've picked up.

 

[icma]

Can I use these circuits to drive the CCFL for PC illumination? They come
with the inverters but they I'd like to mod so I can use 1 inverter for
multiple bulbs. Thanks