Hello all,
I and building a 6 V DC portable LED beacon. I would like to power it with 4D cells in series or 2D cells in series for 3 V. This Beacon will be used one hour and then put away for a day and then used another hour put away for a day. My primary focus is brightness. 100° viewing angle would be more than adequate. I can have one vertical LED and one the horizontal horizontal LED. Any help advice would be super appreciate it. Thank you. Tom

 

Is there a reason you are building one instead of choosing from the many already available?

 

I'm always amazed how 3rd world countries can't get stuff like an off the shelf LED beacon but yet can easily get the IC's/Components,etc.. to build one from scratch..

 

All research has shown very low intensity LEDs. Battery life is always the driving force it seems. My primary goal is long range visibility in the open ocean.

 

#3
Today, 12:07 PM
mcgyvr
Senior Member

Join Date: Oct 2009
Location: North Carolina, USA
Posts: 2,280

I'm always amazed how 3rd world countries can't get stuff like an off the shelf LED beacon but yet can easily get the IC's/Components,etc.. to build one from scratch..

It's going to be a process, but I'm slowly working through it. Your right about the supply chain in Asia. I tried an Asian beacon and the issue was massive power consumption and a large bulky form factor that was not waterproof. I need a simple simple design

 

All research has shown very low intensity LEDs. Battery life is always the driving force it seems. My primary goal is long range visibility in the open ocean.

OK, so that means white light with a horizontal dispersion up to 100° with relatively little vertical dispersion required.

How much light do you want? I mean, can you define the watts or lumens that you want? Please also define what you mean by "flashing", in terms of frequency and duty cycle. Do you want it to rotate, or just flash?

 

Just flash will be fine and I believe Limens will be limited by the 9 volt supply I would like to use 4-6 nine volts in parallel.

 

100 flashes per min. So it's different than anything on the ocean

 

LED color? With one horizontal LED, how do you keep it pointing in desired direction? What range? How high above water?

 

I'm wondering if there are maritime regulations regarding such things.

And I still don't understand what's wrong with the MANY commercial options:
Vega
Edwards
Pharos
MSM

These all look nicely engineered and purpose built. I think it's a little bit of hubris to think a DIY will be better.

 

LED color? With one horizontal LED, how do you keep it pointing in desired direction? What range? How high above water?

Color : red
It's mounted in clear, sealed lexan tube.
The light mounts to a 10" collar that has ballast at its base. I have tested it and the dummy light mounted at 18" above water level remained vertical in 6' seas

 

These all look nicely engineered and purpose built. I think it's a little bit of hubris to think a DIY will be better.

#1. None of the Beacons have a true vertical projection LED.
#2 my form factor for the specific project is very important non of these represent weight and physical characteristics of what I need.
#3 Quite a bit of engineering and testing has gone into my enclosure. It's one that fits my purposes exactly. The enclosure is very specific.

 

Ah well, it would have been helpful to learn these details earlier.

So do you envision a single red LED, or perhaps a strip of several? Since you want red, you might look at automotive LED tails lights, or something like this.

Brightness trades off with battery capacity and length of service. So far you haven't specified any of those 3 requirements. I recommend against the 9V batteries because of their low capacity.

The flashing part will be easy once the power supply and LED are identified. You'll use a 555 timer circuit driving a MOSFET switch. Depending on what you need, you can have control over both frequency and duty cycle.

 

I just tried out a flashing { 100 ms on 900 ms off ] red piranah LED, 120 deg, 66mA, 2.5V, in full sun at 300ft & still visable. Battery 3 AA Ni-MH 2400 mAhr, so should last for 140 h. AA alk have about same Ah but V drops quickly under load. If I were stuck with alk. a small boost-buck board would hold V constant, but would still need 3 to keep 3 V at near end of life. Looks like a Cree CP42B-RKS-CLOPOAA4 is about the same as the one I used. LED is still visable for full 180 deg

 

Bernard, thank you for the advice. I cut and paste the Cree LED that you recommended but was unable to find it on Crees website. 180 degrees of visibility would be awesome.

 

Is the high side switch chosen because the 555 output pulls low better than it pulls high? In other words, why not the usual low side switch?

 

wayneh, right on, would like about 14 mA base current which pushes C555 high output.
Digi-Key SN: CP42B-RKS-CLOPOAA4-ND, $.20; also Mouser & others.