Visit our Popular Forums

Skylark · 08-09-2010, 09:46

I have been working on LED lights using the 1W star types, which are Luxeons or similar to them, using a simple voltage regulator with a LM317 and a couple of resistors. It seems to be reliable. The output is about half of a 60W 120V incandescent light, which is not super bright but usable. The total cost is under $15 per set of three, including the voltage regulator. The power draw is about 4W total. They work off of 12V dc power. I may be able to run 6 LEDs off of one voltage regulator, but have not tried that yet.

I need some ideas on how to mount the LEDs in a housing so they look decent.

There are three star LEDs in a set, and I hope to have lenses on them when the order comes in.

Does anyone have good ideas on how to mount star LEDs on a bulkhead, or over the galley?

Skylark · 08-09-2010, 13:46

Parts list

3 pcs 1W Star LED, rated at max 3.3V, $3.20
STARLED_1W_WW
Star LED

1pcs LM317T voltage regulator, TO-220 type, 1.5 amp design current, $0.65
LM317T LM317 - 1.5A Adjustable Positive Regulator
http://www.futurlec.com/Linear/LM317T.shtml
Linear Series - Voltage Regulators

1pcs R220R12W 220ohm 1/2W 5% Carbon Film Resistor, $0.15 for 10
Resistors 1W

1 pcs TRIM5K 5K 1/4W Min. Horizontal Pot, $0.15
Trimpots

The voltage regulator circuit is shown on this pdf, on page 1.
LM317T Datasheet

Note that when looking at the LM317, the left pin is Adj, the middle is Vout, and the right is Vin.

To make the voltage regulator, connect the 220 ohm resistor between the Vout pin and the Adj pin. Connect the 5k variable resistor between the Adj pin and ground. Connect a 12V (nominal) battery power positive to the Vin pin, and negative to the ground.

The output voltage positive is at Vout, negative at ground. Adjust the variable resistor to get a voltage of just under 9.9V, which is three times the maximum voltage of the LED. The resistance is about 1400 ohms, but measure the voltage output.

Use 14 gauge solid insulated wire to connect the LEDs. This stiff wire allows the LEDs to be aimed as needed. There are positive + markings and negative - markings on the star LEDs. Connect the three LEDs in series, positive to negative. After making sure the voltage regulator output is not above 9.9V, connect the outer LEDs to the positive and negative output of the voltage regulator.

The light output of the three 1W LEDs is about equivalant to a 40W bulb, maybe a little less, and they use about 4W. Be aware that the LEDs and voltage regulator get hot.

Matt Johnson · 08-09-2010, 14:15

Thanks for the parts list... this should be a fun project! I bought a load of Sensibulbs, but I'm sure I will find a use for these too.

**noelex 77** · 08-09-2010, 14:45

Quote:

Originally Posted by Skylark

I

I need some ideas on how to mount the LEDs in a housing so they look decent.

Does anyone have good ideas on how to mount star LEDs on a bulkhead, or over the galley?

I did not like most of the commercial lights, so I made my own. Here is the prototype with a 3w cree emitter.

Skylark · 08-09-2010, 18:04

**noelex 77** · 09-09-2010, 00:08

When doing a progect like this it is worth using quality LED's. The latest Cree emmitter, for example, is likely to produce something like 2X the amount of light for the same powerconsumption as the STARLED_1W_WW you are using.

anjou · 09-09-2010, 00:26

The ones im using are 7 or 9 or 12 SMED's mounted on a board with G4 side pins to fit in the recessed fittings

goboatingnow · 09-09-2010, 01:41

Its worth pointing out that these leds really need a constant current source rather then a constant voltage one. Smart controllers also increase the current as the LED ages to compensate for the decreasing light output over time

Dave

Skylark · 09-09-2010, 03:30

One point I should have mentioned for those who might want to try this out: the variable resistor (trimpot, trim potentiometer) has three pins. Use the center pin and one of the outside pins, either one.

This system is meant for a non-technician like me to be able to build. I don't know of a current controller than can be easily built. The LM317 can be used as a current controller, but it needs a 2W resistor to do that. I could not find resistors of the right ohm value in 2W. Voltage control is easy and uses cheap components. A constant current controller or pulsed system would be better but then the cost goes up.

There are 3W star LEDs on the same page as in the link above. I recommend trying them out. They should work with the same circuit. I have not tried the 3W LEDs yet.

gettinthere · 09-09-2010, 04:31

Quote:

Originally Posted by anjou

The ones im using are 7 or 9 or 12 SMED's mounted on a board with G4 side pins to fit in the recessed fittings

Brand?
Source?
Cost?

**noelex 77** · 09-09-2010, 05:40

Quote:

Originally Posted by Skylark

This system is meant for a non-technician like me to be able to build. I don't know of a current controller than can be easily built. The LM317 can be used as a current controller, but it needs a 2W resistor to do that. I could not find resistors of the right ohm value in 2W. Voltage control is easy and uses cheap components. A constant current controller or pulsed system would be better but then the cost goes up.

.

As you mention more expensive, but there are lots of constant current LED driver modules pre made that are available
Cutter Electronics

mikereed100 · 09-09-2010, 08:57

Here's another constant current controller that shouldn't break the bank.
3023 Wired BuckPuck - LED Supply.com

Shrew · 09-09-2010, 10:10

Quote:

Originally Posted by anjou

The ones im using are 7 or 9 or 12 SMED's mounted on a board with G4 side pins to fit in the recessed fittings

I replaced all the Halogen bulbs with these:

LED Bulbs -12 vt. - Swego.com

They use the g4 pins as well and was as simple as replacing a bulb. When I asked the manufacturer, they indicated there was no need for voltage regulation, resistors etc. Am I overlooking something, or is that only needed for 24v systems? Everything on my boat is 12v.