"lupi" wrote in message
...
Also, I want to make an anchor light with 6 of the 60 degree lamps
flashing so fast they look like they are all on- kind of like the
moving pictures principle. A 555 timer chip, a capacitor, a current
limiting resistor? In theory this would still only drawn the current
of one lamp. Is any of this practical? Thanks again.

An anchor light is not supposed (or even allowed to) flash.....

Meindert

I think he wants to flash them beyond the threshold of perception. What's
that...about 20 hertz? But isn't there something off the shelf that would be
simpler than breadboarding transistors?
At the rate LEDs are taking over lighting the world, somebody in Taiwan may
have solved this problem already.
Good luck,
Boat_dreams.

Meindert Sprang wrote:
"lupi" wrote in message
...

Also, I want to make an anchor light with 6 of the 60 degree lamps
flashing so fast they look like they are all on- kind of like the
moving pictures principle. A 555 timer chip, a capacitor, a current
limiting resistor? In theory this would still only drawn the current
of one lamp. Is any of this practical? Thanks again.


An anchor light is not supposed (or even allowed to) flash.....

Meindert


I believe he wants to strobe them faster than the eye can percieve.
something like 50 hz would do it.


--
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degraded state of moral and patriotic feeling which thinks that nothing
is worth war is much worse."
John Stewart Mill


I strongly urge everyone reading this to check out WWW.anysoldier.us,
and support our troops with a letter, a package or a donation.

You can buy LED lights for a reasonable price down at the local truck stop,
but how do you mount these puppies? Anybody know? It's just got the lamp
itself, no mounting hardware ...the guy at the counter is clueless. Looks
like maybe they are designed to fit in a rubber channel or something?
Anybody?

Brian D

PS: These are cheaper than buying the LED tail lights designed for boat
trailers, so it could mean a cheap upgrade if I can figure out the right way
to mount them....

"dazed and confuzed" wrote in message
...
I believe he wants to strobe them faster than the eye can percieve.
something like 50 hz would do it.

Ah, now I understand. But this has no benefits. A LED that is continuously
on at, say 20mA, will appear to have the same brightness as when strobed
with a 20% duty-cycle (1/5 of the time) at 100mA (5 times the current).

Meindert

On Sat, 27 Nov 2004 08:03:59 +0100, "Meindert Sprang"
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

"dazed and confuzed" wrote in message
...
I believe he wants to strobe them faster than the eye can percieve.
something like 50 hz would do it.

Ah, now I understand. But this has no benefits. A LED that is continuously
on at, say 20mA, will appear to have the same brightness as when strobed
with a 20% duty-cycle (1/5 of the time) at 100mA (5 times the current).

Meindert



Actually not quite. If you talk energy consumption then you are right.
But you can viciously overdrivve LEDs to get far more brightness out
of then than they normally can give.

see:
http://www.stockeryale.com/i/leds/lit/app001.htm

There is also argument that your eye and brain think that the led is
still alight and this can fool you into seeing a brighter LED. I would
reckon this would work best for LEDs being looked _at_, rather than
thiose used as a source of illumination.

"Old Nick" wrote in message
...
Actually not quite. If you talk energy consumption then you are right.
But you can viciously overdrivve LEDs to get far more brightness out
of then than they normally can give.

see:
http://www.stockeryale.com/i/leds/lit/app001.htm

I know, I have used that principle to drive IR leds to illuminate a scenery
for the time of one frame of a video camera.

There is also argument that your eye and brain think that the led is
still alight and this can fool you into seeing a brighter LED. I would
reckon this would work best for LEDs being looked _at_, rather than
thiose used as a source of illumination.

Mmm.... I'd thought that the eye/brain combination would average it, but on
the other hand, the mind can do strange thinks. I'll might try it some day
by comparing two LEDs next to eachother, one continuously driven and the
other with a duty cycle.

Meindert

You need to do it as a blind study. Your preknowledge of which is driven
how may color your perception in something as subtle as that.

--
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"Meindert Sprang" wrote in message
...
"Old Nick" wrote in message
...
Actually not quite. If you talk energy consumption then you are right.
But you can viciously overdrivve LEDs to get far more brightness out
of then than they normally can give.

see:
http://www.stockeryale.com/i/leds/lit/app001.htm

I know, I have used that principle to drive IR leds to illuminate a
scenery
for the time of one frame of a video camera.

There is also argument that your eye and brain think that the led is
still alight and this can fool you into seeing a brighter LED. I would
reckon this would work best for LEDs being looked _at_, rather than
thiose used as a source of illumination.

Mmm.... I'd thought that the eye/brain combination would average it, but
on
the other hand, the mind can do strange thinks. I'll might try it some day
by comparing two LEDs next to eachother, one continuously driven and the
other with a duty cycle.

Meindert

On Sat, 27 Nov 2004 16:21:18 +0100, "Meindert Sprang"
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

"Old Nick" wrote in message
.. .
Actually not quite. If you talk energy consumption then you are right.
But you can viciously overdrivve LEDs to get far more brightness out
of then than they normally can give.

see:
http://www.stockeryale.com/i/leds/lit/app001.htm

I know, I have used that principle to drive IR leds to illuminate a scenery
for the time of one frame of a video camera.

OK. Sorry. Then I misunderstood your argument, unless you were talking
about actual efficiency. You seemed to say that strobing had no gain.


There is also argument that your eye and brain think that the led is
still alight and this can fool you into seeing a brighter LED. I would
reckon this would work best for LEDs being looked _at_, rather than
thiose used as a source of illumination.

Mmm.... I'd thought that the eye/brain combination would average it, but on
the other hand, the mind can do strange thinks. I'll might try it some day
by comparing two LEDs next to eachother, one continuously driven and the
other with a duty cycle.

I carefully said there was "some argument" about this! G ABob says,
you need to test with extreme care.

Perceived brightness is proportional to average physical power output
of flashing light sources except for relatively low flash rates.
Above the critical flicker fusion rate (the flashing rate above which
the source does not appear to pulsate), the visual system responds
only to average power, not peak power. Consequently, there is no
perceptual advantage to pulsing LEDs at high rates. However, LEDs
themselves do not have output directly proportional to current, and
this fact can sometimes be used to improve physical power output by
pulsing. For example, if a particular LED has its highest flux output
per milliamp input at 100 milliamps, and the available current is
10mA, then the LED will have higher output pulsed 100mA with 10% duty
factor than operated with DC at 10mA. In other words, if you're
application requires operating the LED at an average current below its
point of highest efficiency, pulsing can be advantageous. On the
other hand, if you're trying to get the absolute maximum amount of
brightness from a given LED within its ratings, DC is always best.
This point has been debated thoroughly in sci.electronics.design and
elsewhere, and you can find more info he

http://www2.whidbey.net/opto/LEDFAQ/...Q%20Pages.html

Lighting for electronic cameras (as in the Stocker and Yale link) is
an entirely different matter. Flashing LEDs in sync with camera
frames is an obvious way to reduce power dissipation in the LEDs, but
there is no human visual parallel.

Paul Mathews


Old Nick wrote in message . ..
On Sat, 27 Nov 2004 08:03:59 +0100, "Meindert Sprang"
vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

"dazed and confuzed" wrote in message
...
I believe he wants to strobe them faster than the eye can percieve.
something like 50 hz would do it.

Ah, now I understand. But this has no benefits. A LED that is continuously
on at, say 20mA, will appear to have the same brightness as when strobed
with a 20% duty-cycle (1/5 of the time) at 100mA (5 times the current).

Meindert



Actually not quite. If you talk energy consumption then you are right.
But you can viciously overdrivve LEDs to get far more brightness out
of then than they normally can give.

see:
http://www.stockeryale.com/i/leds/lit/app001.htm

There is also argument that your eye and brain think that the led is
still alight and this can fool you into seeing a brighter LED. I would
reckon this would work best for LEDs being looked _at_, rather than
thiose used as a source of illumination.