flashlight circuit

R

rabbit killer

Guest
why the hell does my flashlight go dim, but when I knock it hard it gets
bright again? What can I do to fix this? I don't understand what's going
on here...
 
"rabbit killer" <siccusproprius@gmx.com> wrote in message
news:i2kqt6$b95$1@news.albasani.net...
why the hell does my flashlight go dim, but when I knock it hard it gets
bright again? What can I do to fix this? I don't understand what's going
on here...
Click to expand...
The bulb is getting less voltage than it needs.
Most likely cause is contact resistance.
Clean every place contact is made.
Battery ends, spring to battery, bulb to battery, switch contacts. A pencil
eraser works on most of it. If the switch is sealed you don't need to worry
about it.
Also check where the reflector rim touches the contact and make sure the
bulb is tight.
Did I miss anything guys?

Tom
 
Tom Biasi wrote:
"rabbit killer" <siccusproprius@gmx.com> wrote in message
news:i2kqt6$b95$1@news.albasani.net...
why the hell does my flashlight go dim, but when I knock it
hard it
gets bright again? What can I do to fix this? I don't
understand
what's going on here...

The bulb is getting less voltage than it needs.
Most likely cause is contact resistance.
Clean every place contact is made.
Battery ends, spring to battery, bulb to battery, switch
contacts. A
pencil eraser works on most of it. If the switch is sealed you
don't
need to worry about it.
Also check where the reflector rim touches the contact and make
sure
the bulb is tight.
Did I miss anything guys?

Only the possibility that the OP was trolling.
Click to expand...
 
On Tue, 27 Jul 2010, pimpom wrote:

Tom Biasi wrote:
"rabbit killer" <siccusproprius@gmx.com> wrote in message
news:i2kqt6$b95$1@news.albasani.net...
why the hell does my flashlight go dim, but when I knock it
hard it
gets bright again? What can I do to fix this? I don't
understand
what's going on here...

The bulb is getting less voltage than it needs.
Most likely cause is contact resistance.
Clean every place contact is made.
Battery ends, spring to battery, bulb to battery, switch
contacts. A
pencil eraser works on most of it. If the switch is sealed you
don't
need to worry about it.
Also check where the reflector rim touches the contact and make
sure
the bulb is tight.
Did I miss anything guys?

Only the possibility that the OP was trolling.

Huh?
Click to expand...

The original problem is pretty common, and I sure remember knocking
flashlights about in order to get them working again.

Flashlights are simple, and have virtually no soldered parts. So the
contact between the bulb and the rest of the circuit is merely pressure
contact, the switches are often on a similar level.

Those can suffer, maybe the worse because of the current drain of the
bulb.

LED flashlights don't suffer because they aren't put together with
pressure, and there's no surge as the bulb first receives current and
heats up.

Michael
 
Michael Black wrote:
On Tue, 27 Jul 2010, pimpom wrote:

Tom Biasi wrote:

"rabbit killer" <siccusproprius@gmx.com> wrote in message
news:i2kqt6$b95$1@news.albasani.net...

why the hell does my flashlight go dim, but when I knock it
hard it
gets bright again? What can I do to fix this? I don't
understand
what's going on here...


The bulb is getting less voltage than it needs.
Most likely cause is contact resistance.
Clean every place contact is made.
Battery ends, spring to battery, bulb to battery, switch
contacts. A
pencil eraser works on most of it. If the switch is sealed you
don't
need to worry about it.
Also check where the reflector rim touches the contact and make
sure
the bulb is tight.
Did I miss anything guys?

Only the possibility that the OP was trolling.

Huh?

The original problem is pretty common, and I sure remember knocking
flashlights about in order to get them working again.

Flashlights are simple, and have virtually no soldered parts. So the
contact between the bulb and the rest of the circuit is merely pressure
contact, the switches are often on a similar level.

Those can suffer, maybe the worse because of the current drain of the bulb.

LED flashlights don't suffer because they aren't put together with
pressure, and there's no surge as the bulb first receives current and
heats up.

Michael
Click to expand...
Spot on, except for the thing about LED flashlights.
You're probably sensible enough to buy *good* ones.

The cheap ones I've seen sure do, but not because of high
current. Some of them use a solder ball (blob?) to
contact the battery + terminal, and a crappy spring at
the other end. Dissassembly, cleaning, sometimes stretching
the spring, and sometimes adding to the solder ball restores
operation. For a while. :)

Ed
 
"Michael Black" <et472@ncf.ca> wrote in message
news:pine.LNX.4.64.1007271039220.1081@darkstar.example.net...
On Tue, 27 Jul 2010, pimpom wrote:


The original problem is pretty common, and I sure remember knocking
flashlights about in order to get them working again.

Michael

For a long time when I was a kid I thought that's how they're supposed to
Click to expand...
work.

Tom
 
Michael Black wrote:
On Tue, 27 Jul 2010, pimpom wrote:

Tom Biasi wrote:
"rabbit killer" <siccusproprius@gmx.com> wrote in message
news:i2kqt6$b95$1@news.albasani.net...
why the hell does my flashlight go dim, but when I knock it
hard it
gets bright again? What can I do to fix this? I don't
understand
what's going on here...

The bulb is getting less voltage than it needs.
Most likely cause is contact resistance.
Clean every place contact is made.
Battery ends, spring to battery, bulb to battery, switch
contacts. A
pencil eraser works on most of it. If the switch is sealed
you
don't
need to worry about it.
Also check where the reflector rim touches the contact and
make
sure
the bulb is tight.
Did I miss anything guys?

Only the possibility that the OP was trolling.

Huh?

The original problem is pretty common, and I sure remember
knocking
flashlights about in order to get them working again.

Flashlights are simple, and have virtually no soldered parts.
So the
contact between the bulb and the rest of the circuit is merely
pressure contact, the switches are often on a similar level.

Those can suffer, maybe the worse because of the current drain
of the
bulb.

LED flashlights don't suffer because they aren't put together
with
pressure, and there's no surge as the bulb first receives
current and
heats up.

If the OP was serious, I apologise. The problem is so common and
Click to expand...
the cause so obvious (not only to me, but also to all the
non-technical people I know who had experienced it) that I
doubted that it was a serious question. Those non-technical types
may not be able to explain it as clearly as did Mr.Tom Biasi, but
I've known them all to immediately diagnose it with terms like
"bad contact", "something loose", "corrosion", "bulb loose in the
socket", "weak spring", "worn out switch", etc.
 
--
MikeK
"pimpom" <pimpom@invalid.invalid> wrote in message
news:i2neje$9ik$1@news.albasani.net...
Michael Black wrote:
On Tue, 27 Jul 2010, pimpom wrote:

Tom Biasi wrote:
"rabbit killer" <siccusproprius@gmx.com> wrote in message
news:i2kqt6$b95$1@news.albasani.net...
why the hell does my flashlight go dim, but when I knock it
hard it
gets bright again? What can I do to fix this? I don't
understand
what's going on here...

The bulb is getting less voltage than it needs.
Most likely cause is contact resistance.
Clean every place contact is made.
Battery ends, spring to battery, bulb to battery, switch
contacts. A
pencil eraser works on most of it. If the switch is sealed you
don't
need to worry about it.
Also check where the reflector rim touches the contact and make
sure
the bulb is tight.
Did I miss anything guys?

Only the possibility that the OP was trolling.

Huh?

The original problem is pretty common, and I sure remember knocking
flashlights about in order to get them working again.

Flashlights are simple, and have virtually no soldered parts. So the
contact between the bulb and the rest of the circuit is merely
pressure contact, the switches are often on a similar level.

Those can suffer, maybe the worse because of the current drain of the
bulb.

LED flashlights don't suffer because they aren't put together with
pressure, and there's no surge as the bulb first receives current and
heats up.

If the OP was serious, I apologise. The problem is so common and the cause
so obvious (not only to me, but also to all the non-technical people I
know who had experienced it) that I doubted that it was a serious
question. Those non-technical types may not be able to explain it as
clearly as did Mr.Tom Biasi, but I've known them all to immediately
diagnose it with terms like "bad contact", "something loose", "corrosion",
"bulb loose in the socket", "weak spring", "worn out switch", etc.

I'm more used to hearing "it must be a short" from the non-technical types.
Click to expand...
MikeK :)
 
amdx wrote:
Michael Black wrote:
On Tue, 27 Jul 2010, pimpom wrote:

Tom Biasi wrote:
"rabbit killer" <siccusproprius@gmx.com> wrote in message
news:i2kqt6$b95$1@news.albasani.net...
why the hell does my flashlight go dim, but when I knock
it
hard it
gets bright again? What can I do to fix this? I don't
understand
what's going on here...

The bulb is getting less voltage than it needs.
Most likely cause is contact resistance.
Clean every place contact is made.
Battery ends, spring to battery, bulb to battery, switch
contacts. A
pencil eraser works on most of it. If the switch is sealed
you
don't
need to worry about it.
Also check where the reflector rim touches the contact and
make
sure
the bulb is tight.
Did I miss anything guys?

Only the possibility that the OP was trolling.

Huh?

The original problem is pretty common, and I sure remember
knocking
flashlights about in order to get them working again.

Flashlights are simple, and have virtually no soldered parts.
So the
contact between the bulb and the rest of the circuit is
merely
pressure contact, the switches are often on a similar level.

Those can suffer, maybe the worse because of the current
drain of
the bulb.

LED flashlights don't suffer because they aren't put together
with
pressure, and there's no surge as the bulb first receives
current
and heats up.

If the OP was serious, I apologise. The problem is so common
and the
cause so obvious (not only to me, but also to all the
non-technical
people I know who had experienced it) that I doubted that it
was a
serious question. Those non-technical types may not be able to
explain it as clearly as did Mr.Tom Biasi, but I've known them
all
to immediately diagnose it with terms like "bad contact",
"something
loose", "corrosion", "bulb loose in the socket", "weak
spring",
"worn out switch", etc.
I'm more used to hearing "it must be a short" from the
non-technical
types. MikeK
:)
Click to expand...
Oh yeah, that too. But most often in connection with higher power
levels than a flashlight. It must stem from the fact that short
circuits often produce sparks and burning. So whenever they
observe a spark at an electrical joint or contact, they call it a
short. And since shorts often result in an open circuit, they
sometimes also call that a short.
 
On Tue, 27 Jul 2010 10:41:49 -0400, Michael Black <et472@ncf.ca> wrote:

On Tue, 27 Jul 2010, pimpom wrote:

Tom Biasi wrote:
"rabbit killer" <siccusproprius@gmx.com> wrote in message
news:i2kqt6$b95$1@news.albasani.net...
why the hell does my flashlight go dim, but when I knock it
hard it
gets bright again? What can I do to fix this? I don't
understand
what's going on here...

The bulb is getting less voltage than it needs.
Most likely cause is contact resistance.
Clean every place contact is made.
Battery ends, spring to battery, bulb to battery, switch
contacts. A
pencil eraser works on most of it. If the switch is sealed you
don't
need to worry about it.
Also check where the reflector rim touches the contact and make
sure
the bulb is tight.
Did I miss anything guys?

Only the possibility that the OP was trolling.

Huh?

The original problem is pretty common, and I sure remember knocking
flashlights about in order to get them working again.

Flashlights are simple, and have virtually no soldered parts. So the
contact between the bulb and the rest of the circuit is merely pressure
contact, the switches are often on a similar level.

Those can suffer, maybe the worse because of the current drain of the
bulb.

LED flashlights don't suffer because they aren't put together with
pressure, and there's no surge as the bulb first receives current and
heats up.

Michael
Click to expand...
Most of the LED flashlights I have are subject to dimming out now and then. I
have found that it is almost always due to a poor electrical connection between
the PC board the LEDs are soldered to and the case of the flashlight. These
flashlights have the on/off switch on the end of the cylinder opposite the LEDs.
There are solder pads around the perimeter of the LED pc board that on my oldest
lights attempted to have the connection by making a solder blob that stuck out
beyond the perimeter of the pc board and was held in place by pressure from the
cap on the led end of the light. The next attempt was to solder small "whisker
wires" to the solder pads, allowing the wires to wedge between the edge of the
pc board and case as the lens cap was screwed on. The most recent examples, and
by far the most reliable, has a continuous braid of copper soldered to the pads,
again friction fit to the case as the end cap is threaded on the LED end of the
light. I bought these lights from the same place over about a six month period.
I have not had any LEDs go bad individually. Power is via 3 AA cells in a
paralell pack in the barrel of the light. regards, Joe.
pcfixr@upwardaccess.com
 
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