I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.

Oh, and the lamp is *metal*.

Michael Koblic,
Campbell River, BC

wrote:

I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.

A diode. Cut out half of the AC cycle and get reduced brightness. Very,
very common, indeed there are/were little socket insert disks made that
you stuck in a light socket to save power.

Pete C. wrote:
wrote:

I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.


A diode. Cut out half of the AC cycle and get reduced brightness. Very,
very common, indeed there are/were little socket insert disks made that
you stuck in a light socket to save power.

A friends son has a filament lamp which has 3 intensities and off and
cycles between them when you touch the metal lamp base itself, no switch
just contact. How would that be done.

David Billington wrote:

Pete C. wrote:
wrote:

I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.


A diode. Cut out half of the AC cycle and get reduced brightness. Very,
very common, indeed there are/were little socket insert disks made that
you stuck in a light socket to save power.

A friends son has a filament lamp which has 3 intensities and off and
cycles between them when you touch the metal lamp base itself, no switch
just contact. How would that be done.

Simple touch switch controller, uses several fixed levels of regular
triac phase control for the dimming. You can buy the control module for
like $5 to add to any lamp that has some metal surface you can use for
the touch switch.

On Tue, 28 Feb 2012 01:38:18 +0000, David Billington
wrote:

Pete C. wrote:
wrote:

I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.


A diode. Cut out half of the AC cycle and get reduced brightness. Very,
very common, indeed there are/were little socket insert disks made that
you stuck in a light socket to save power.

A friends son has a filament lamp which has 3 intensities and off and
cycles between them when you touch the metal lamp base itself, no switch
just contact. How would that be done.
Capacitive touch switch and a "tri-lite" bulb.

On 2012-02-28, David Billington wrote:
Pete C. wrote:
wrote:

I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

[ ... ]

I am posting here to see how widely this trick is known.

A diode. Cut out half of the AC cycle and get reduced brightness. Very,
very common, indeed there are/were little socket insert disks made that
you stuck in a light socket to save power.

A friends son has a filament lamp which has 3 intensities and off and
cycles between them when you touch the metal lamp base itself, no switch
just contact. How would that be done.

First off -- the base is serving as an antenna to pick up stray
AC noise from the room, and when you touch it you increase the level to
above a pre-set threshold. It then waits for the noise to go down below
the threshold and back up again to switch to the next.

If the bulb is not a three-way bulb (two filaments of different
wattages used one at a time or both together), then it probably has a
transformer with its secondary in series with the AC line to the lamp,
and switched to either aid, oppose, or switched out of the circuit
entirely. This should give you three brightnesses.

Or, another (cheaper) way to get the brightnesses (with the same
switching sensor for the touch base trick) would be to change the width
of the part of the AC cycle which is allowed to reach the lamp -- like a
dimmer with three steps instead of continuously variable. Since that is
cheaper, it is probably how they went. Try picking it up and judging by
the weight whether it has a transformer in the base.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

wrote in message
...
I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.

Oh, and the lamp is *metal*.

Michael Koblic,
Campbell River, BC

Unlike a regular tungsten filament lamp, a halogen lamp actually will burn
out much more quickly at reduced power if the temperture of the envelope
drops below the point needed for the halogen cycle.
http://en.wikipedia.org/wiki/Halogen...#Halogen_cycle

On 2012-02-28, wrote:
I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

The way I would do it is to put a diode in series with the lamp
on the low-intensity setting. I would guess that it is possible that
the diode could be inside the switch housing.

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.

Oh, and the lamp is *metal*.

That is good -- so many are plastic these days. :-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 28 Feb 2012 03:09:25 GMT, "DoN. Nichols"
wrote:

On 2012-02-28, wrote:
I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

The way I would do it is to put a diode in series with the lamp
on the low-intensity setting. I would guess that it is possible that
the diode could be inside the switch housing.

Correct. A dirt-cheap 1N5404, hidden inside the switch. Half-wave
rectifier properties etc. have already been mentioned.

I thought it was a neat trick. A resistor achieving the same thing
would have to be of the order of 17W or so.

BTW neither the people who sold the lamp nor the experts in the two
specialist electrical shops knew the answer.

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.

Oh, and the lamp is *metal*.

That is good -- so many are plastic these days. :-)

Purely so I don't have mark the thread "OT".

Michael Koblic,
Campbell River, BC

Many semiconductors wouldn't exist if not for deposited forms of various
metals.. nor would many forms of illumination devices.

So generally, still on topic even if by trace amounts, which is far greater
than many of the bull**** hero worship/hate posts appearing every day.

--
WB
..........


wrote in message
...
On 28 Feb 2012 03:09:25 GMT, "DoN. Nichols"
wrote:

snippets not present

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

The way I would do it is to put a diode in series with the lamp
on the low-intensity setting. I would guess that it is possible that
the diode could be inside the switch housing.

Correct. A dirt-cheap 1N5404, hidden inside the switch. Half-wave
rectifier properties etc. have already been mentioned.

I thought it was a neat trick. A resistor achieving the same thing
would have to be of the order of 17W or so.

BTW neither the people who sold the lamp nor the experts in the two
specialist electrical shops knew the answer.

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.

Oh, and the lamp is *metal*.

That is good -- so many are plastic these days. :-)

Purely so I don't have mark the thread "OT".

Michael Koblic,
Campbell River, BC

On 2012-02-29, wrote:
On 28 Feb 2012 03:09:25 GMT, "DoN. Nichols"
wrote:

On 2012-02-28, wrote:
I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

The way I would do it is to put a diode in series with the lamp
on the low-intensity setting. I would guess that it is possible that
the diode could be inside the switch housing.

Correct. A dirt-cheap 1N5404, hidden inside the switch. Half-wave
rectifier properties etc. have already been mentioned.

I thought it was a neat trick. A resistor achieving the same thing
would have to be of the order of 17W or so.

And the resistor would be sensitive to the wattage of the bulb
installed -- assuming that it was a kind where various bulbs would fit
it. And the switch would probably get rather uncomfortably hot to the
touch after a while of operation. :-)

BTW neither the people who sold the lamp nor the experts in the two
specialist electrical shops knew the answer.

Of course not. They aren't members of this newsgroup, where
people care how and why things work.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

wrote

Correct. A dirt-cheap 1N5404, hidden inside the switch. Half-wave
rectifier properties etc. have already been mentioned.

I thought it was a neat trick. A resistor achieving the same thing
would have to be of the order of 17W or so.

BTW neither the people who sold the lamp nor the experts in the two
specialist electrical shops knew the answer.

Michael Koblic,
Campbell River, BC

There's an old parlor trick with two switches and two bulbs wired in a
series loop where each switch controls a bulb independently.
http://img517.imageshack.us/img517/7...circuit1tb.jpg
http://img291.imageshack.us/img291/1263/circuit25jw.jpg

You build it with porcelain-base knife switches and lamp sockets each
on a separate small wood block, connected with a single strand of
solid or clear-insulation speaker wire.

With both switches open, both bulbs are off. Close either switch and
its bulb lights even though the other switch is plainly open -- that's
the reason for using knife switches. There is enough open space under
the porcelain base for the diodes, which the wood blocks keep
concealed. Don't show it to technicians who might carry screwdrivers
(like me) and ask to disassemble it.

No one ever notices that the bulbs aren't at full brightness.

I don't have a photo of mine, I took it apart because it is so
dangerous.

jsw

Jim Wilkins wrote:

There's an old parlor trick with two switches and two bulbs wired in a
series loop where each switch controls a bulb independently.
http://img517.imageshack.us/img517/7...circuit1tb.jpg
http://img291.imageshack.us/img291/1263/circuit25jw.jpg

You build it with porcelain-base knife switches and lamp sockets each
on a separate small wood block, connected with a single strand of
solid or clear-insulation speaker wire.

With both switches open, both bulbs are off. Close either switch and
its bulb lights even though the other switch is plainly open -- that's
the reason for using knife switches. There is enough open space under
the porcelain base for the diodes, which the wood blocks keep
concealed. Don't show it to technicians who might carry screwdrivers
(like me) and ask to disassemble it.

No one ever notices that the bulbs aren't at full brightness.

I don't have a photo of mine, I took it apart because it is so
dangerous.


AKA: "The Impossible circuit". You could build one today with LEDs
and a wall wart.


--
You can't have a sense of humor, if you have no sense.

Jim Wilkins wrote:

There's an old parlor trick with two switches and two bulbs wired in a
series loop where each switch controls a bulb independently.

....

No one ever notices that the bulbs aren't at full brightness.

I don't have a photo of mine, I took it apart because it is so
dangerous.

Cute. You could power it with a 24v transformer & use 12v bulbs, for
full brightness and a safe circuit.

Bob

On Wed, 29 Feb 2012 09:07:23 -0500, "Jim Wilkins"
wrote:

[...]

I don't have a photo of mine, I took it apart because it is so
dangerous.

The concept of dangerous electrical circuits brings back all kinds of
nostalgic memories.

When I worked for a film company (a 1000 years ago) there were two
favorite ways of boiling water for coffee on location:

1) A large wattage resistor connected directly to mains used as an
immersion heater. Note: The mains were 220V.

2) A cup with two plates on top of each other but not touching, each
connected to mains. Pour water directly into the cup, plug in. This
arrangement boiled water literally in 3 seconds.

Yet the only mortality I remember was work-related: A broken cable
under water.

Michael Koblic,
Campbell River, BC

wrote:
On Wed, 29 Feb 2012 09:07:23 -0500, "Jim Wilkins"
wrote:

[...]

I don't have a photo of mine, I took it apart because it is so
dangerous.

The concept of dangerous electrical circuits brings back all kinds of
nostalgic memories.

When I worked for a film company (a 1000 years ago) there were two
favorite ways of boiling water for coffee on location:

1) A large wattage resistor connected directly to mains used as an
immersion heater. Note: The mains were 220V.

2) A cup with two plates on top of each other but not touching, each
connected to mains. Pour water directly into the cup, plug in. This
arrangement boiled water literally in 3 seconds.

Yet the only mortality I remember was work-related: A broken cable
under water.

One of our high school projects was a wiener
cooker comprised of a plastic shoebox, a
micro-switch and rows of nails to impale the
ends of the unfortunate wieners.
Plug it in and wait for the hot dogs to
cook.

Worked great.

--Winston-- I don't figure they'd do that today.

You ever cook hot dogs with the plug, cord, and two nails?

Christopher A. Young
Learn more about Jesus
www.lds.org
..

wrote in message
...
On Wed, 29 Feb 2012 09:07:23 -0500, "Jim Wilkins"

The concept of dangerous electrical circuits brings back all kinds of
nostalgic memories.

When I worked for a film company (a 1000 years ago) there were two
favorite ways of boiling water for coffee on location:

1) A large wattage resistor connected directly to mains used as an
immersion heater. Note: The mains were 220V.

2) A cup with two plates on top of each other but not touching, each
connected to mains. Pour water directly into the cup, plug in. This
arrangement boiled water literally in 3 seconds.

Yet the only mortality I remember was work-related: A broken cable
under water.

Michael Koblic,
Campbell River, BC

Already been answered, but it's the same method used in some cheap models of
soldering irons for a hi-lo selector switch.

When diodes are used with light bulbs, I find the flicker very annoying. I
bought an advanced-technology? high intensity lamp a number of years ago
(maybe $8 or more, definitely more than several boxes of normal
incandescents), and it turned out to contain an internal diode, which made
it useless for me, for close-up work requiring more light.

It was an odd lamp, in that it weighed a lot (probably about a pound) and
was thick glass (thicker than a typical outdoor flood/spot lamp), and had a
coating of some strange foggy, translucent rubbery coating on the outside of
the glass envelope.
It may have been a Sylvania product, and had weird angled conical shapes
with a flat top when held upright (threaded base pointing down).

Turn it upside down and put a cap on it, and some artsy design school
marketing type would think it an attractive bottle for a new product
rollout.. thinking back further, it looked like a cologne bottle I remember
from the 60s.

--
WB
..........


wrote in message
...
I have a bedside lamp with a 100W halogen lamp which runs directly off
110V. In the base of the lamp is a small rotary switch about 3/4" in
diameter. It has three positions: Full intensity, reduced intensity
and off. No other parts are discernible.

The question is: How does the lamp achieve the reduction in light
intensity (about half)?

I actually know the answer because I took the switch apart but when I
was looking for it before on Google etc. I could not find it.

I am posting here to see how widely this trick is known.

Oh, and the lamp is *metal*.

Michael Koblic,
Campbell River, BC

On Monday, February 27, 2012 8:14:14 PM UTC-5, wrote:

[stuff about a diode in series with a lamp]

I put a diode in series with the two lights flanking my front door. In 28 years, I have changed those bulbs only twice. They really like the lower operating temperature, and the orange light is much less annoying than bright white.