I've got a nice bronze navigation light that sits on my taffrail. The outside is good, I have a new globe for it, but the inside electricals are corroded.
See:
http://picasaweb.google.com/fongemie/Lights
I originally thought it would be nice to rewire this using LEDs, and got a good deal on some "high intensity" units on ebay. I can stuff three or four in there facing out and it looks great, lights up nice, I can even leave the old socket in place..however on further research I discover these "old style" LEDs need a current regulator in the circuit somewhere. Not sure I want to mess with that. I found newer style LED's (DR.LED) but these are all "incandescent bulb style" and require the socket, which brings be back to the corroded socket problem.
Anyone know where to get a LED setup that I can just wire directly? Or, I'd be happy to just replace the socket that's in there if I can get it out. I've looked at Radio Shack and an auto supply store with no luck. Any recommendations on where to find the socket, or even an exact name for the thing so I can search the internet for one?
Thanks for any help.
Rewiring an old navigation light
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preserved_killick
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Proper LED control is done using constant current regulator circuitry, but for a 12V boat system whose voltage doesn't vary much, a properly sized resistor in line with the LED would provide adequate current control. If you want to discuss, send me a PM.
One other thing to keep in mind is that the light won't officially be USCG approved with the modified lighting element. Just an FYI.
One other thing to keep in mind is that the light won't officially be USCG approved with the modified lighting element. Just an FYI.
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Ceasar Choppy
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My experience has been that finding just a regular LED STERN light that mounts on the taff rail is a pain. Lopolight makes one that is great, but at almost $300, I can buy a lot of batteries for my incandescent lights before it saves me anything.
Innovative Solutions and Attwood make deck mounted LED nav lights but they only make the side lights and not the stern lights. I suspect that is because you only find them marketed to stinkpotters.
If you can't find a DR. LED replacement, try some of the bulbs over at http://www.superbrightleds.com. They have a socket bulb that is mounted at a 90 angle that might work for you.
Edit: take a look at the one on this page: http://superbrightleds.com/specs/1156-x30.htm
Innovative Solutions and Attwood make deck mounted LED nav lights but they only make the side lights and not the stern lights. I suspect that is because you only find them marketed to stinkpotters.
If you can't find a DR. LED replacement, try some of the bulbs over at http://www.superbrightleds.com. They have a socket bulb that is mounted at a 90 angle that might work for you.
Edit: take a look at the one on this page: http://superbrightleds.com/specs/1156-x30.htm
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preserved_killick
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Thanks Ceasar,
By looking at the page you linked to, I discovered that the bulb type id called "bayonete" (I didn't know). I was then able to find a new Perko socket at Jamestown:
http://www.jamestowndistributors.com/us ... amp+Socket
If I can get my crusty socket out, I can replace it with the new socket and I'm in business for either LED or incandescent.
Those leds you linked to are cheap!.
-Jeff
By looking at the page you linked to, I discovered that the bulb type id called "bayonete" (I didn't know). I was then able to find a new Perko socket at Jamestown:
http://www.jamestowndistributors.com/us ... amp+Socket
If I can get my crusty socket out, I can replace it with the new socket and I'm in business for either LED or incandescent.
Those leds you linked to are cheap!.
-Jeff
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Tony
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I'm with Ryan.
All you need to limit the current is put a properly sized resistor inline. The led will drop a particular voltage across it (likely .7V, but check the specs for the led). You put a resistor inline that will limit the current to what the led specs call for.
Ohms law says: V=IR. You're interested in I (current) so do some mathemagic and I=V/R. Here's your circuit:
(+)--------/\/\/\--------|>|-------------(-)
12V Resistor X LED
11.3V .7V
So....
Let's say, hypothetically, your LED calls for a max current of 200mA RMS. That means:
200mA=11.3V/R ---->mathemagic---> R=11.3/200mA so R=5,650 ohms (or a 5.6K resisitor). Now go down to Rat Shack or your preferred local electronics place and find a resistor with a similar value.
Obviously this is hypothetical, you'll have to look up the specs of your LED to figure the value you need.
*Edit: This is a simple one led circuit. For multiple LED's, just include them in your circuit and add up the voltage drops for each one, subtract that from the total and you get the V you need to calculate with. Example, 3 LED's that drop .7V drop a total 2.1V so the resistor will drop 9.9V.*
All you need to limit the current is put a properly sized resistor inline. The led will drop a particular voltage across it (likely .7V, but check the specs for the led). You put a resistor inline that will limit the current to what the led specs call for.
Ohms law says: V=IR. You're interested in I (current) so do some mathemagic and I=V/R. Here's your circuit:
(+)--------/\/\/\--------|>|-------------(-)
12V Resistor X LED
11.3V .7V
So....
Let's say, hypothetically, your LED calls for a max current of 200mA RMS. That means:
200mA=11.3V/R ---->mathemagic---> R=11.3/200mA so R=5,650 ohms (or a 5.6K resisitor). Now go down to Rat Shack or your preferred local electronics place and find a resistor with a similar value.
Obviously this is hypothetical, you'll have to look up the specs of your LED to figure the value you need.
*Edit: This is a simple one led circuit. For multiple LED's, just include them in your circuit and add up the voltage drops for each one, subtract that from the total and you get the V you need to calculate with. Example, 3 LED's that drop .7V drop a total 2.1V so the resistor will drop 9.9V.*
Tony
One correction to Tony's calculation, the R value would be 56.5 ohms in his example instead of 5.6k ohms.
Another thing to keep in mind is the power rating of the resistor. Once you have the resistor value with Tony's method, then the power dissipated by the resistor is equal to the current through the resistor squared times the value of the resistor.
P=I^2 * R
So for the example above,
P= (200mA)^2 * 56.5 ohms
P=2.26W
You would have to make sure you bought a resistor that would dissipate more than 2.26 watts.
Tony, I think we are getting dangerously close to the "Nerdery" forum!!
Good Luck!
Another thing to keep in mind is the power rating of the resistor. Once you have the resistor value with Tony's method, then the power dissipated by the resistor is equal to the current through the resistor squared times the value of the resistor.
P=I^2 * R
So for the example above,
P= (200mA)^2 * 56.5 ohms
P=2.26W
You would have to make sure you bought a resistor that would dissipate more than 2.26 watts.
Tony, I think we are getting dangerously close to the "Nerdery" forum!!
Good Luck!
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Ceasar Choppy
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This place has been around for a while now and I used to get most of my LEDs from them before Sensabulb and Dr. LED existed.preserved_killick wrote: Those leds you linked to are cheap!.
-Jeff
But it is about as nerdy as I get. No offense guys, but if we're talking about adding resistors, the nerd factor is too great. Its worth it to me to spend a few bucks to just replace it.
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preserved_killick
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Guys,
I think we've gone past the "nerdy line". How the heck do you add a resistor to the circuit? It's not like the thing has plugs. The only way I've seen resistors used is with a circuit board. I've just got a red wire, and a black wire. Red goes to red, black goes to black. Not much more do I know.
Actually, the explanations are clear, and I understand what I need to do and why, I just don't know the mechanics of putting such a thing together.
I believe, that I'd be using three LEDs in parallel (three red wires from three LEDs going to my positive lead, three black wires from the leds going to the ground. Can these resistors be connected in-line on the positive lead prior to the LEDs?
I think we've gone past the "nerdy line". How the heck do you add a resistor to the circuit? It's not like the thing has plugs. The only way I've seen resistors used is with a circuit board. I've just got a red wire, and a black wire. Red goes to red, black goes to black. Not much more do I know.
Actually, the explanations are clear, and I understand what I need to do and why, I just don't know the mechanics of putting such a thing together.
I believe, that I'd be using three LEDs in parallel (three red wires from three LEDs going to my positive lead, three black wires from the leds going to the ground. Can these resistors be connected in-line on the positive lead prior to the LEDs?
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Tony
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Ryan,
Thanks for the correction. I did the calculation on the fly and transposed a decimal.
The rest of y'all,
Hey, it's who I am. Me, in all my nerdy glory! (Just wait until I show you my low voltage alarm circuit).
Mechanically, what I do is solder the resistor inline with the led and cover it with some adhesive heat-shrink. It's not that hard. OR if you must you can put the LED and resistor on a very small circuit board and mount the board in the light. You can get little 2x2 blanks (you can cut them down if you need to) at Rat Shack or any other local phon-ah, I mean electronics supply store. ("Ratshack...you've got questions, we've got cell phones.".)
Thanks for the correction. I did the calculation on the fly and transposed a decimal.
The rest of y'all,
Hey, it's who I am. Me, in all my nerdy glory! (Just wait until I show you my low voltage alarm circuit).
Mechanically, what I do is solder the resistor inline with the led and cover it with some adhesive heat-shrink. It's not that hard. OR if you must you can put the LED and resistor on a very small circuit board and mount the board in the light. You can get little 2x2 blanks (you can cut them down if you need to) at Rat Shack or any other local phon-ah, I mean electronics supply store. ("Ratshack...you've got questions, we've got cell phones.".)
Last edited by Tony on Fri Jul 25, 2008 11:16 am, edited 1 time in total.
Tony
The resistor would be soldered to the anode (positive wire) of the LED.
For a parallel string of LEDs, the best bet is to put a resistor in line with each LED and then connect them in parallel.
Aside from the nerd factor, I was originally under the impression that the original poster was using just plain LEDs. The LEDs that Ceasar Choppy and preserved_killick are referring to probably already have a resistor included. Anytime a single LED has a working voltage of 12VDC, the resistor is already in the circuit. In that case, I agree that the easiest thing to do is buy a replacement as the calculations and construction have already been done for you.
The only other gotchas with the white LEDs are to make sure the color is warm enough so you don't have a light that is too bluish and that the beam width is wide enough to give you the coverage that you need for visibility.
Ryan
For a parallel string of LEDs, the best bet is to put a resistor in line with each LED and then connect them in parallel.
Aside from the nerd factor, I was originally under the impression that the original poster was using just plain LEDs. The LEDs that Ceasar Choppy and preserved_killick are referring to probably already have a resistor included. Anytime a single LED has a working voltage of 12VDC, the resistor is already in the circuit. In that case, I agree that the easiest thing to do is buy a replacement as the calculations and construction have already been done for you.
The only other gotchas with the white LEDs are to make sure the color is warm enough so you don't have a light that is too bluish and that the beam width is wide enough to give you the coverage that you need for visibility.
Ryan
Last edited by Ryan on Fri Jul 25, 2008 12:40 pm, edited 2 times in total.
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Tony
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On a serious note,
You may need to use more than three LED's. These devices typically have a fairly narrow beam width, and if you have to cover 180 degrees (this is a stern light, right?) you may need a couple more to get full coverage. This may actually be a good place to use a circuit board and build it yourself because you can use the circuit board to "aim" the LED's in the right direction.
I just found a pretty straight forward layman's explanation of DIY LED lighting here with a basic current limiting circuit that's pretty easy and cheap to build.
You may need to use more than three LED's. These devices typically have a fairly narrow beam width, and if you have to cover 180 degrees (this is a stern light, right?) you may need a couple more to get full coverage. This may actually be a good place to use a circuit board and build it yourself because you can use the circuit board to "aim" the LED's in the right direction.
I just found a pretty straight forward layman's explanation of DIY LED lighting here with a basic current limiting circuit that's pretty easy and cheap to build.
Tony
