Ikea Dioder?

Adrian

while you are on, do you have any white(ish) LED lighting with controllable brightness for use over a chart table to preserve night vision, please ?

(This follows the current night vision thread)

thanks
 
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You can get cheap buck-boost controllers, from eBay of course!
e.g.:
http://www.ebay.co.uk/itm/3-5-28V-t..._Measurement_Equipment_ET&hash=item51ab7d061a

Alternatively you could switch in a buck or dropping regulator when charging the batteries, or not run the lights from a battery that is being charged.
I would be cautious of conducted and radiated interference in any installation using switch mode regulation.
You may need to add more filtering/suppression. You may find that Navtex is the most vulnerable.

The current in a simple resistor controlled LED circuit is proportional to (Vin-Vdiodes) where Vdiodes is usually 3 leds in series at 3point something volts each, so the current can easily double when fast charging at 16V.
That's not good unless the current is derated to start with, which is a possible approach as the LEDs don't change colour (much) at lower current, you just need more of 'em for the same light.

If I was wiring a boat tomorrow, I'd fit a stabilised 12V supply for LEDs. Retrofitting piecemeal is more of an issue.
Also, do not forget that most regulators will have a quiescent current when all the lights are off, so will draw a few mA 24/7 unless isolated. The eBay one linked to draws 10mA allegedly.
That might matter if you had several of them or left them live over the winter.
I know one boat with a permanently live feed to a light inside the companionway, so you can switch the batteries on or off in the dark.
 
sarabande said:
Adrian

while you are on, do you have any white(ish) LED lighting with controllable brightness for use over a chart table to preserve night vision, please ?

(This follows the current night vision thread)

thanks
Click to expand...

Just switch in a few resistors.
A 1W led fitting will probably have 3v/80ma = 37 ohm or so in series, so try adding something similar? A 39ohm 1/4watt resistor should do as a starting point?
 
sarabande said:
Adrian

while you are on, do you have any white(ish) LED lighting with controllable brightness for use over a chart table to preserve night vision, please ?

(This follows the current night vision thread)

thanks
Click to expand...

Here is a link that dims at the click of a key fob:

http://www.youtube.com/watch?v=CdhzJU2LRPk&feature=youtu.be

Purchased from this site and very easy to install. Does not need to be a white LED that is controlled. Also useful for having at end of bunk or anywhere where you just want to turn a light (or any other device) on / off or somewhere in between at the click of a button:
http://www.allproductdesign.co.uk/Electronics.html

Scroll down to find it.

This device (actually there is an updated version whereby the user can select constant current and an LED illuminates to PROVE constant current is maintained)
http://www.youtube.com/watch?v=c850zqFtLn0
 
gadget user said:
Sorry to butt in, but how bright are the emergency nav lights you sell with the LED replacement for £24, please on your site at:
http://www.boatlamps.co.uk/contents/en-uk/d187.html
Click to expand...

I don't have a precise Lumen output figures for the new lamps as yet as they are still under development. The lamps are being produced by the best LED flashlight manufacturer in the Far East and our unique 1.5 volt lamp production has to be fitted in between much larger orders! The sample lamps I have approved are significantly brighter than the original incandescent lamps they replace. I have had 48 hours of light with a AA cell and using a D cell they last for around 5 days!

The increase in light output was the main reason for developing the lamp, it makes this widely sold emergency light kit actually useful, whereas the original light output was pretty abysmal rendering the emergency light set fit only for the bottom of a locker. I have used the new lights on a tender with the new LED lamps fitted and the tender lights were clearly visible across Portsmouth harbour from Hasler Marina. I think they will be widely used as tender lights which will increase the visibility of small boats. In emergency they can be used to light a boat should an individual light or whole power system fail.

Before any questions on COLREGS compliance are asked, no they don't comply, but pragmatically they are significantly better than no lights at all which is also very much non compliant!

Regards
 
You have a couple of options for night use over a chart table. You could use a dual red/white output LED lamp. We have a planar disc LED product that fits standard down light fixtures the lamp has a diameter of only 30mm. A simple toggle of the switch changes light output from red to white light, a further toggle changes it back to red. I also have a new 12v or 24v dimmer switch coming, it not yet on our web site, It smoothly dims the full range of our constant current lamps and is actually UK made!!! It comes mounted on a switch plate or in PCB form so users can incorporate the dimmer in their own panel. Its simple to install and perfect for DIY. Please email me if you need further information on any of our new products.

Regards
 
nigelmercier said:
Ohms Law doesn't work with non-linear components, although the voltage does stay about the same as you say.
Click to expand...

I was only applying Ohm's Law to the series resistors, the voltage across the LEDs is roughly constant, so can be just taken off the source voltage.
Near enough for these pruposes anyway.

It is often possible to read the resistor values used on surface mount LED assemblies, but don't be caught out by the format, which is usually two numbers and a power of ten multiplier, so '390' would mean 39 ohms , 39 times ten^0, and 101 is 100, 10 times 10^1.
The LED lamps I have in front of me have 120ohms for each chain of 3 leds. There are four chains of LEDs, so equivalent to 4 120ohm res's in parallel, or 30ohms. Putting say 47ohms in series dims it handily.
 
I was just reading the earlier warning on page 2 and was wondering if anyone has any documented cases of leds causing fire, just for interests sake.
 
causeway said:
I was just reading the earlier warning on page 2 and was wondering if anyone has any documented cases of leds causing fire, just for interests sake.
Click to expand...

No, but I know someone who had a good attempt with a halogen reading lamp.
 
causeway said:
I was just reading the earlier warning on page 2 and was wondering if anyone has any documented cases of leds causing fire, just for interests sake.
Click to expand...

I saw it on youtube somewhere. I will try to find it, probably under chinese LEDs or EBAY LED's or something.
 
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