Xenon flashlight bulb bypass capacitor?

[John Doe]

This is my question:
Can a bypass capacitor help increase the life of a xenon bulb? If so
please tell me what general type of capacitor.

If any regular here is familiar with xenon light bulbs, I'm sure this
is a simple question for you.

I just bought a light weight, extremely bright dual Xenon flashlight.
Replacement bulbs are difficult to get. They will be switched on and
off frequently.

They look like medium to large size clear LEDs each with two short
leads. I guess it's six volts per xenon bulb, I will multimeter
voltage/current/resistance stuff if that might help.

The work involved is no problem.

Thank you.





--
I realize this is in submicron transistor stuff, but I'm not sure any
other group would be better.

 

[John Larkin]

On Sat, 29 Jan 2005 01:03:34 GMT, John Doe
<jdoe@usenet.is.the.real.thing> wrote:

This is my question:
Can a bypass capacitor help increase the life of a xenon bulb?

Sorry, no.

John

 

[John Woodgate]

I read in sci.electronics.design that John Doe <jdoe@usenet.is.the.real.
thing> wrote (in <Xns95ECC1E2BAC7wisdomfolly@151.164.30.44&gt about
'Xenon flashlight bulb bypass capacitor?', on Sat, 29 Jan 2005:

Can a bypass capacitor help increase the life of a xenon bulb? If so
please tell me what general type of capacitor.

No. But a very low value series resistor would. However, it does reduce
brightness. A more complicated inrush-current limiter would work, but
again there would be a loss of brightness unless you use a relay (or
maybe a selected power FET) to short-circuit a series resistor after a
0.5 second delay.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[SioL]

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message news:hRuNS4AXpz+BFwao@jmwa.demon.co.uk...

I read in sci.electronics.design that John Doe <jdoe@usenet.is.the.real.
thing> wrote (in <Xns95ECC1E2BAC7wisdomfolly@151.164.30.44&gt about
'Xenon flashlight bulb bypass capacitor?', on Sat, 29 Jan 2005:

Can a bypass capacitor help increase the life of a xenon bulb? If so
please tell me what general type of capacitor.

No. But a very low value series resistor would. However, it does reduce
brightness. A more complicated inrush-current limiter would work, but
again there would be a loss of brightness unless you use a relay (or
maybe a selected power FET) to short-circuit a series resistor after a
0.5 second delay.

Self-heating NTC resistor?

S

 

[John Doe]

John Woodgate <jmw@jmwa.demon.contraspam.yuk> wrote:

John Doe <jdoe@usenet.is.the.real.thing> wrote

Can a bypass capacitor help increase the life of a xenon bulb? If
so please tell me what general type of capacitor.

No. But a very low value series resistor would. However, it does
reduce brightness. A more complicated inrush-current limiter would
work, but again there would be a loss of brightness unless you use
a relay (or maybe a selected power FET) to short-circuit a series
resistor after a 0.5 second delay.

How about a coil?

 

[SioL]

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message news:tFiOXHDma3+BFw6j@jmwa.demon.co.uk...

I read in sci.electronics.design that SioL <Sio_spam_L@same.net> wrote
(in <LjJKd.8625$F6.1584710@news.siol.net&gt about 'Xenon flashlight bulb
bypass capacitor?', on Sat, 29 Jan 2005:
"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message news:hRuNS4AXpz
+BFwao@jmwa.demon.co.uk...
I read in sci.electronics.design that John Doe <jdoe@usenet.is.the.real.
thing> wrote (in <Xns95ECC1E2BAC7wisdomfolly@151.164.30.44&gt about
'Xenon flashlight bulb bypass capacitor?', on Sat, 29 Jan 2005:

Can a bypass capacitor help increase the life of a xenon bulb? If so
please tell me what general type of capacitor.

No. But a very low value series resistor would. However, it does reduce
brightness. A more complicated inrush-current limiter would work, but
again there would be a loss of brightness unless you use a relay (or
maybe a selected power FET) to short-circuit a series resistor after a
0.5 second delay.

Self-heating NTC resistor?

In theory, yes, but I don't know of any that would do the job for a low-
voltage xenon lamp. Might be worth looking round.

I've seen a similar solution offered for a regular 220V mains lamp,
many many years ago (15+ years).
Of course current is a lot smaller there so a few ohms might be tolerable,
whereas for a xenon, probably not.

S

 

[Guy Macon]

Read this:

http://members.misty.com/don/bulb1.html

It answers all your questions about extending the life of
Xenon (Halogen) bulbs.

--
Guy Macon <http://www.guymacon.com/>

 

[Fred Bloggs]

Guy Macon wrote:

Read this:

http://members.misty.com/don/bulb1.html

It answers all your questions about extending the life of
Xenon (Halogen) bulbs.

The optimum methodology for life extension is to not use it all- anyone
can see that.

 

[John Woodgate]

I read in sci.electronics.design that Guy Macon <http@?.guymacon.com/>
wrote (in <10vn5id61irq7e4@corp.supernews.com&gt about 'Xenon flashlight
bulb bypass capacitor?', on Sat, 29 Jan 2005:

Read this:

http://members.misty.com/don/bulb1.html

It answers all your questions about extending the life of Xenon
(Halogen) bulbs.

Xenon lamps and halogen lamps are not at all the same thing. Xenon is a
dense inert gas, which allows a higher filament temperature to be
achieved without excessive evaporation of the filament. Halogens are
highly reactive elements, and in a tungsten lamp set up a transport
mechanism whereby filament atoms that escape from the bulk filament are
returned to it.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[John Larkin]

On Sat, 29 Jan 2005 07:25:11 +0000, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that John Doe <jdoe@usenet.is.the.real.
thing> wrote (in <Xns95ECC1E2BAC7wisdomfolly@151.164.30.44&gt about
'Xenon flashlight bulb bypass capacitor?', on Sat, 29 Jan 2005:

Can a bypass capacitor help increase the life of a xenon bulb? If so
please tell me what general type of capacitor.

No. But a very low value series resistor would. However, it does reduce
brightness. A more complicated inrush-current limiter would work, but
again there would be a loss of brightness unless you use a relay (or
maybe a selected power FET) to short-circuit a series resistor after a
0.5 second delay.

I've read (an ancient GE appnote, I think) that blinking incandescents
doesn't really reduce their life. They do tend to die at turnon, but
they were just about to go anyhow, so that didn't reduce their life
much.

The resistor would greatly extend life because of the voltage drop.
Life is inverse on something outrageous like the 12th power of
voltage.

John

 

[Guy Macon]

John Woodgate wrote:

Xenon lamps and halogen lamps are not at all the same thing. Xenon is a
dense inert gas, which allows a higher filament temperature to be
achieved without excessive evaporation of the filament. Halogens are
highly reactive elements, and in a tungsten lamp set up a transport
mechanism whereby filament atoms that escape from the bulk filament are
returned to it.

(Smacks self in the head) D'oh! I have no idea why I gave an answer
appropriate for Iodine after reading the word Xenon. Brain fart, pure
and simple. (hangs head in shame)

 

[John Doe]

For what it's worth, here are some specs for the Brinkman MAXFIRE
dual xenon rechargeable flashlight:

.... current at battery terminal is 2.30 amps with both lamps on
.... current at battery is 1.16 amps with only the top lamps on
.... current at bottom xenon bulb when both bulbs are on is 1.13 amps
.... battery voltage is 6.5 volts
.... disconnected xenon bulb resistances are .5 and .6 ohms

The flashlight circuit includes:
.... two electrolytic capacitors
.... three transistors
.... three 1% resistors
.... eight 5% resistors
.... two 1N4... diodes
.... one or two small voltage diodes

Unless all that is for switching, maybe it already includes something
for current regulation.

Here is a blurry picture of the circuit (I need a better camera).

http://f1.pg.briefcase.yahoo.com/logicshaping@sbcglobal.net

"flashlight circuit.jpg"

battery maker is Power One
part number 04G10 or KT625
battery rating 6 volts, 2.5 amp hours

I voided the warrantee, I usually void the warrantee before even
touching a device. Mind over matter.







--
Everybody knows what the subject is, thanks for all the useful
information.

 

[Don Klipstein]

In article <TVFBjSD7h3+BFwdH@jmwa.demon.co.uk>, John Woodgate wrote:

I read in sci.electronics.design that John Doe <jdoe@usenet.is.the.real.
thing> wrote (in <Xns95ED2ACA34486wisdomfolly@151.164.30.44&gt about
'Xenon flashlight bulb bypass capacitor?', on Sat, 29 Jan 2005:

How about a coil?

You mean using an inductor to limit the inrush? I doubt that it's
practicable. The required L/R ratio is too high. I don't know what lamp
you have or what a suitable inrush current limit is, but for a 6 V
supply and a 6 V 1 A lamp, to limit the initial rate of change of
current to 1 A/s, assuming zero cold resistance for the lamp, you need a
6 H inductor. The resistance needs to be well below 0.6 ohm so as not to
affect brightness. OK, the inductor can saturate when the full current
is flowing, but that's still a sizeable inductor.

Since most filaments experience most of their temperature rise from a
cold start in a fraction of 1/10 of a second, I believe most of whatever
actual benefit there is from inrush protection is achieved if the time
constant is slowed down only to 1/10 of a second. Maybe as long as 1/5 of
a second.

So that 6 H inductor becomes a 1.2 or .6 H one...

Still does not sound practical to me!

I think better to use a power MOSFET that has low resistance, a low
value current sense resistor, and appropriate circuitry to add to this
to achieve a slow increase in current... and see whether or not there is
much gain in lamp life - I doubt it.

- Don Klipstein (don@misty.com)