On Wed, 27 May 2009 08:57:01 +0200, "Meindert Sprang"
wrote:

wrote in message
.. .

Unfortunately, switch mode regulators often introduce noise that
affects other more important things on a boat.

A well-designed SMPS does not introduce noise. But it will increase cost of
course.....

Meindert


Tiny point of use switch mode power supplies, as used for LED
lighting, are often noisy. More often than not.

In article , "WBH" wrote:
You can put led lights in series, but then you always have to switch more
lights on than you need. The whole idea of led lighting is to be more
efficient with DC and that translates to being able to switch lights
individually. The only way to efficiently supply power to leds is by using
constant current regulators, that use PWM (pulse width modulation). Any
other circuitry, be it transistor or Vreg, produces heat and is therefore
inefficient. Cheap led drivers can be found he
http://www.dealextreme.com/details.dx/sku.13553
cheers,
wbh

Well I guess the regulators are cheaper than the leds now.
At least these imports.
These are interesting but what the hell are those prongs for ?
Would be interesting to see the specs and the switching frequency.
Free shipping fro Hong Kong. Good.

greg




"Geoff Schultz" wrote in message
. ..
| A couple of years ago I installed DoctorLED
| (http://www.doctorled.com/p24.htm) Mars Dome interior lights throughout
| BlueJacket. This was the first shipment of these to the US and I literally
| had to wait for them to get off of the container and into my hands before
I
| could depart for the NW Caribbean. They may have changed the design since
| then, but this is what I've got.
|
| Anyhow, about a year later I realized that they were getting dimmer and
| dimmer and recently took a failed unit over to a friend who's an excellent
| electronics engineer to determine what had failed. He found 2 problems
with
| the units:
|
| 1) There's a layer of thermal paste which is supposed to conduct the heat
| between the circuit board that the LEDs are mounted on and the aluminum
| backing plate which also functions as a heat sink. For all intents and
| purposes, there was too little paste to provide contact between the two.
| However, after running a working unit for about 10 minutes, there was no
| appreciable heat buildup, so we don't suspect that my problem was due to
| thermal overheating.
|
| 2) The basic design of the circuit is a transistor which limits the
voltage
| to 9V to 2 parallel stacks of 3 LEDs in series. This provides 3 V to each
| LED, which is just fine. However, the transistor is too slow to handle
fast
| transient voltage spikes, and there's no voltage dump circuitry on the
| boards to handle this. A spike probably occurred somewhere along the line
| and fried some of the LEDs.
|
| DoctorLED will sell me replacement circuit boards at about 1/2 of the cost
| of the whole unit, which is still expensive. I plan to do that, but I want
| to protect against this happening in the future. All of the lighting is on
| 2 separate circuits. What can I do to protect against this happening
again?
| I was thinking about a 12 V DC to DC power supply. Any suggestions?
|
|
| -- Geoff
| www.GeoffSchultz.org

In article ,
"Meindert Sprang" wrote:

wrote in message
...

Unfortunately, switch mode regulators often introduce noise that
affects other more important things on a boat.

A well-designed SMPS does not introduce noise. But it will increase cost of
course.....

Meindert

Åbsolutly, to keep the noise down, all you got to do is round of the
corners of those square pulses, just a bit.... doesn't hurt the
Regulation a bit.....

--
Bruce in alaska
add path after fast to reply

In article , "WBH" wrote:
You can put led lights in series, but then you always have to switch more
lights on than you need. The whole idea of led lighting is to be more
efficient with DC and that translates to being able to switch lights
individually. The only way to efficiently supply power to leds is by using
constant current regulators, that use PWM (pulse width modulation). Any
other circuitry, be it transistor or Vreg, produces heat and is therefore
inefficient. Cheap led drivers can be found he
http://www.dealextreme.com/details.dx/sku.13553
cheers,
wbh


I am looking through the stuff. Great stuff. They
even have clicky switches.

18 watt LED !!


"Geoff Schultz" wrote in message
. ..
| A couple of years ago I installed DoctorLED
| (http://www.doctorled.com/p24.htm) Mars Dome interior lights throughout
| BlueJacket. This was the first shipment of these to the US and I literally
| had to wait for them to get off of the container and into my hands before
I
| could depart for the NW Caribbean. They may have changed the design since
| then, but this is what I've got.
|
| Anyhow, about a year later I realized that they were getting dimmer and
| dimmer and recently took a failed unit over to a friend who's an excellent
| electronics engineer to determine what had failed. He found 2 problems
with
| the units:
|
| 1) There's a layer of thermal paste which is supposed to conduct the heat
| between the circuit board that the LEDs are mounted on and the aluminum
| backing plate which also functions as a heat sink. For all intents and
| purposes, there was too little paste to provide contact between the two.
| However, after running a working unit for about 10 minutes, there was no
| appreciable heat buildup, so we don't suspect that my problem was due to
| thermal overheating.
|
| 2) The basic design of the circuit is a transistor which limits the
voltage
| to 9V to 2 parallel stacks of 3 LEDs in series. This provides 3 V to each
| LED, which is just fine. However, the transistor is too slow to handle
fast
| transient voltage spikes, and there's no voltage dump circuitry on the
| boards to handle this. A spike probably occurred somewhere along the line
| and fried some of the LEDs.
|
| DoctorLED will sell me replacement circuit boards at about 1/2 of the cost
| of the whole unit, which is still expensive. I plan to do that, but I want
| to protect against this happening in the future. All of the lighting is on
| 2 separate circuits. What can I do to protect against this happening
again?
| I was thinking about a 12 V DC to DC power supply. Any suggestions?
|
|
| -- Geoff
| www.GeoffSchultz.org

"GregS" wrote in message
...
| In article , "WBH"
wrote:
| You can put led lights in series, but then you always have to switch more
| lights on than you need. The whole idea of led lighting is to be more
| efficient with DC and that translates to being able to switch lights
| individually. The only way to efficiently supply power to leds is by
using
| constant current regulators, that use PWM (pulse width modulation). Any
| other circuitry, be it transistor or Vreg, produces heat and is therefore
| inefficient. Cheap led drivers can be found he
| http://www.dealextreme.com/details.dx/sku.13553
| cheers,
| wbh
|
| Well I guess the regulators are cheaper than the leds now.
| At least these imports.
| These are interesting but what the hell are those prongs for ?
| Would be interesting to see the specs and the switching frequency.
| Free shipping fro Hong Kong. Good.
|
| greg
|
|
|
|
| "Geoff Schultz" wrote in message
| . ..
| | A couple of years ago I installed DoctorLED
| | (http://www.doctorled.com/p24.htm) Mars Dome interior lights throughout
| | BlueJacket. This was the first shipment of these to the US and I
literally
| | had to wait for them to get off of the container and into my hands
before
| I
| | could depart for the NW Caribbean. They may have changed the design
since
| | then, but this is what I've got.
| |
| | Anyhow, about a year later I realized that they were getting dimmer and
| | dimmer and recently took a failed unit over to a friend who's an
excellent
| | electronics engineer to determine what had failed. He found 2 problems
| with
| | the units:
| |
| | 1) There's a layer of thermal paste which is supposed to conduct the
heat
| | between the circuit board that the LEDs are mounted on and the aluminum
| | backing plate which also functions as a heat sink. For all intents and
| | purposes, there was too little paste to provide contact between the
two.
| | However, after running a working unit for about 10 minutes, there was
no
| | appreciable heat buildup, so we don't suspect that my problem was due
to
| | thermal overheating.
| |
| | 2) The basic design of the circuit is a transistor which limits the
| voltage
| | to 9V to 2 parallel stacks of 3 LEDs in series. This provides 3 V to
each
| | LED, which is just fine. However, the transistor is too slow to handle
| fast
| | transient voltage spikes, and there's no voltage dump circuitry on the
| | boards to handle this. A spike probably occurred somewhere along the
line
| | and fried some of the LEDs.
| |
| | DoctorLED will sell me replacement circuit boards at about 1/2 of the
cost
| | of the whole unit, which is still expensive. I plan to do that, but I
want
| | to protect against this happening in the future. All of the lighting is
on
| | 2 separate circuits. What can I do to protect against this happening
| again?
| | I was thinking about a 12 V DC to DC power supply. Any suggestions?
| |
| |
| | -- Geoff
| | www.GeoffSchultz.org
|

No idea what the prongs are for. I guess these drivers were made for a
specific application. I just de-soldered them and replaced them by wires.
Put heatshrink around the whole thing and put it in the back of the light
fitting. I use them to drive Cree leds. This is what it looks like:
http://www.flickr.com/photos/38407103@N07/ Total DC draw with all the lights
on: 0.9A.
They do produce some noise on the VHF, but that's acceptable as we only use
the interior lights when anchored. I've ordered half a dozen more, because
by the look of it the design has changed somewhat since I bought them and
I'm curious to see if they got rid of the noise.

wout

"Meindert Sprang" wrote in
:

wrote in message
...

Unfortunately, switch mode regulators often introduce noise that
affects other more important things on a boat.

A well-designed SMPS does not introduce noise. But it will increase
cost of course.....

Meindert




Yeah, but what these cheapskates will pay for doesn't even have a .01 cap
across the power bus.....

How do they live with 50AH house batteries??....(c;]


--
-----
Larry

If a man goes way out into the woods all alone and says something,
is it still wrong, even though no woman hears him?

(GregS) wrote in news:gvjhnr$5a3$5
@usenet01.srv.cis.pitt.edu:

Would be interesting to see the specs and the switching frequency.


Every one of them switches at an evenly divisible multiple of 156.800
Mhz.....Just like Adler-Barbour damned
fridges...bzzt...bzzt...bzztbzzt....all night long....

They adjust 'em until their dead on Channel 16....


--
-----
Larry

If a man goes way out into the woods all alone and says something,
is it still wrong, even though no woman hears him?

"Larry" wrote in message
...
Yeah, but what these cheapskates will pay for doesn't even have a .01 cap
across the power bus.....

Not to mention a decent common mode filter at both ends....

Meindert

On Thu, 28 May 2009 08:14:11 +0200, "Meindert Sprang"
wrote:

"Larry" wrote in message
.. .
Yeah, but what these cheapskates will pay for doesn't even have a .01 cap
across the power bus.....

Not to mention a decent common mode filter at both ends....

Meindert


Umm... We are talking about point-of-use power supplies. One at each
LED fixture. It must be physically tiny, and not add exponentially to
the cost of the lamp. Noise is a COMMON issue with LED lighting on
boats.

In article , Larry wrote:
(GregS) wrote in news:gvjhnr$5a3$5
:

Would be interesting to see the specs and the switching frequency.


Every one of them switches at an evenly divisible multiple of 156.800
Mhz.....Just like Adler-Barbour damned
fridges...bzzt...bzzt...bzztbzzt....all night long....

They adjust 'em until their dead on Channel 16....


I am thinking about possible sweeping multiple subharmonics.
from multiple lights.

greg