" JimH" wrote in message
...

"Eisboch" wrote in message
...

" JimH" wrote in message
...

"Bill McKee" wrote in message
.net...

"Eisboch" wrote in message
news
wrote in message
ups.com...
First version, otherwise why use 6 resistors instead of one single
lower ohmage one of higher power.


I was trying to roughly calculate the power requirements. You said
600 ohm resistors, correct? The voltage drop on the LED will be
minimal when forward biased or "on", so each branch must be about .02
amps, times six equals .12 amps, so the power must be about 12v times
.12 or about 1.4 watts. Probably a bit more when you factor in the
LED drop, whatever it is. Significantly less than a regular light
bulb!

Eisboch


Most LED's are in the 400mw range.


How about the standard 12v bulb used for anchor lights?

I don't know what their wattage rating typically is. My guess would be
somewhere between 10 - 20 watts, given that they are required to be seen,
what, 2 miles away at night?

Eisboch



What is the benefit for a boater on the hook overnight besides having a
brighter anchor light? Is there a significant less draw on the house
battery over a 10 hour period?


Yes.

These lights may be purchased with all the dropping resistors built into the
housing.
The OP is a do-it-yourselfer, enjoying the challange of designing his own
circuits.

Eisboch

There is a commercially available LED anchor light that sells for about
$113 but for some strange reason I had to try to make it myself. The
difference in cost is not significant when you consider what most of us
get paid/hr and the time it will take me. In fact, I'll probably lose
money so I am not sure why I am making it myself.

wrote in message
oups.com...
Less than half the draw on the house battery.


Thanks.

I take it this is not a cost effective thing for the casual night boater to
do, unless a brighter light and more visibility is wanted.

" JimH" wrote in message
...

wrote in message
oups.com...
Less than half the draw on the house battery.


Thanks.

I take it this is not a cost effective thing for the casual night boater
to do, unless a brighter light and more visibility is wanted.


Brighter, they are, and that's not a bad thing. They also have a long life
when compared to a regular bulb. It would take a while to recover the
initial cost compared to the cost of replacement bulbs however.

Eisboch

If you have time on your hands, maybe it is cost effective. The LEDs
are about $2.00 each and the resistors cant be any more than $.50 each
and the relay is $4.50 for a total cost of components of about $20.00.

wrote in message
oups.com...
If you have time on your hands, maybe it is cost effective. The LEDs
are about $2.00 each and the resistors cant be any more than $.50 each
and the relay is $4.50 for a total cost of components of about $20.00.


I just checked a USCG approved LED anchor light. 3 watts at 12 volts.
2nm visibility.

Over 100 bucks.

Eisboch

wrote:
OK, my recollection from a web site about LED use said to figure a
voltage drop of 3.4 volts for the white ultrabrights leaving about a 9
volt drop for the resistor. At 600 ohms, this gives about .015 amp
through each resistor and LED. Yes, the correct resistor wattage is
less than 1/4 watt but I hate blowing resistorswhen odd things happen
and space saving is not a consideration here. Radio Shack had nothing
even as alrge as 1/4 watt less than 1000 ohms.


It'd be more efficient to put 2 or 3 LED's in series with one resistor
so more of the power goes to lumens rather than heating resistors.

-rick-

"Eisboch" wrote in message
...

"Bill McKee" wrote in message
.net...

"Eisboch" wrote in message
news

wrote in message
ups.com...
First version, otherwise why use 6 resistors instead of one single
lower ohmage one of higher power.


I was trying to roughly calculate the power requirements. You said 600
ohm resistors, correct? The voltage drop on the LED will be minimal
when forward biased or "on", so each branch must be about .02 amps,
times six equals .12 amps, so the power must be about 12v times .12 or
about 1.4 watts. Probably a bit more when you factor in the LED drop,
whatever it is. Significantly less than a regular light bulb!

Eisboch


Most LED's are in the 400mw range.

Does that include the new, high powered ones? The are being used on
trucks for brake lights, turn signals and other places to replace bulbs.
They are incredibly bright. Maybe the brightness is due to optics being
used, like a Fresnel lens or something.

Eisboch




Maybe a little more, but not much. The trucks use them for the same reason
I went to LED's on the boat trailer. Longevity. they do not have to waste
time, explaining to the cops why the clearance lights are not all working.
They are very voltage sensitive. to little voltage, not enough current and
the LED is black, increase voltage to a point and they get brighter,
increase more and they start getting dimmer, and too much voltage and they
are bright for a few milliseconds, and the magic smoke is released.

wrote in message
oups.com...
If you have time on your hands, maybe it is cost effective. The LEDs
are about $2.00 each and the resistors cant be any more than $.50 each
and the relay is $4.50 for a total cost of components of about $20.00.


There is a seller on EBAY from Asia, that sells the bright LED's for a
decent price. I think the shipping is for 20 at a time.

wrote in message
...
On Thu, 29 Dec 2005 22:15:47 -0500, "Eisboch" wrote:


" JimH" wrote in message
...

wrote in message
oups.com...
Less than half the draw on the house battery.


Thanks.

I take it this is not a cost effective thing for the casual night boater
to do, unless a brighter light and more visibility is wanted.


Brighter, they are, and that's not a bad thing. They also have a long
life
when compared to a regular bulb. It would take a while to recover the
initial cost compared to the cost of replacement bulbs however.

Eisboch


When you are using a bunch of LEDs on a circuit you get every extra
one in series for free. Why waste power through 6 resistors. At least
go 3 and 3 starting with a resistor in the 100 ohm range. I bet they
will drop more than 2v each so you probably can't do six in series.
Even if they light you still want some resistance in there.

There are replacement LED lights that plug into the standard socket. May
have to do a google search for them.