LED bulbs - Page 3 - RC Groups
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Dec 11, 2006, 10:31 PM
Boats on the brain!!
green-boat's Avatar
I'm glad to hear that you have some experience soldering, trying to explain someone if a tough one. Teaching it is a visual thing.

LED's will emit most of thier light from the end in about a 30 degree angle/ cone. Regular light bulbs on the other hand emit most of thier light from the sides. Lightly sanding the sides of an LED with some very fine sandpaper will help with the light issue.
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Dec 12, 2006, 12:16 AM
Taking care of the pond.

Use the http://led.linear1.org/1led.wiz
LED calculator: current limiting resistor value
3 Source voltage
2.1 diode forward voltage
25 diode forward current (mA)

The wizard recommends a 1/8W or greater 39 ohm resistor. The color code for 39 ohms is orange white black.
Dec 12, 2006, 12:54 AM
Registered User
Don, thank you for the additional info; it all helps.
Dec 13, 2006, 02:55 AM
all my boats are broken
ernest2's Avatar
i don't have much knowledge about LED that's probably the reason why all the LED i bought are not working anymore

what does forward voltage means? and how do you know it? i mean if i have a 3volts battery and an led, what's my forward voltage?
Dec 13, 2006, 06:19 AM
Mmm, tugs...
patmat2350's Avatar
Read post 10 in this thread again. Forward Voltage spec is available with new parts bought at Radio Shack, for example.
With an unknown LED: Use 6v, put a 220 ohm resistor in series with the LED. Turn the LED right way around (see post 11). Use a volt meter and measure the voltage dropped across the LED... that is your forward voltage, which will change only slightly if different resistors are used.

Pat M
Dec 13, 2006, 10:42 PM
all my boats are broken
ernest2's Avatar
thanks pat. i have actually read the posts, maybe i just didnt understand it, lol.. LEDs i bought don't have infos on them, so iguess forward voltage is usually 2-3volts with current in the 20mA range (from what i have read while trying to understand more).
for what its worth, i have read this site and found it useful and very knowledgable.
Feb 02, 2008, 03:29 PM
Mmm, tugs...
patmat2350's Avatar
Has anyone opened up the kind of LED Christmas lamps that are shaped like faceted globes or icicles? I'm wondering if they all contain the "M5" LED as shown in post #1 here, and if so, do the colored bulbs have colored LEDs, or "white" LEDs and colored globes?
Feb 02, 2008, 04:10 PM
Mmm, tugs...
patmat2350's Avatar
OK, I just answered one of my questions- I remembered I have some "white" bulbs outside (brrr!) with the pinecone-like globes. Inside- just a standard LED... all the "side lighting" is just from reflectance off the globe's facets.

The LEDs with the inverted-conical tip that directs light out the sides (post #1) are 5mm (or M5) bulbs, and seem to be distributed by Everstar. But not easy to find! However, they are a nice fit inside Robbe's nav lamp housings, once you drill out the clear housing to suit.

I'll try coloring some of their "white" bulbs red and green, will report later...
Feb 02, 2008, 04:11 PM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
Originally Posted by patmat2350
Has anyone opened up the kind of LED Christmas lamps that are shaped like faceted globes or icicles? I'm wondering if they all contain the "M5" LED as shown in post #1 here, and if so, do the colored bulbs have colored LEDs, or "white" LEDs and colored globes?
Mine were 3mm white LED...clear globes
I have used them up, and am waiting for an order of LED to arrive.

But opening up demo strings at Target, the LED are colored. Sizes may vary.

I cast some of the white LED into colored resin for red and green.
It is not nearly as effective as a red or green led in colored resin.
The white LED create a hot spot that overpowers the color "gell".
Feb 02, 2008, 04:36 PM
Mmm, tugs...
patmat2350's Avatar
May be better to color the outside of the lamp housing (like in the real world!)... I'm trying stuff made for doing colored window decorations... goes on opaque, dries clear-red or -green.
Feb 02, 2008, 06:35 PM
Mmm, tugs...
patmat2350's Avatar
OK, I took a Robbe lamp housing (1:20 scale), and drilled out the lens to accept a "white" 5mm LED of the type shown back in post #1.
The lens is coated with red glass decoration paint from the craft store, which dries clear-red. It's a pain to put on uniformly, and it's kind of thick and soft when dry, easy to scratch off. Maybe something else is called for... plain red paint is too opaque, anyone have an idea?

But it works! The whole lens-housing glows red. The photo reveals a white hot spot, but it's not so obvious to the eye.

Pat M
Feb 02, 2008, 10:07 PM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
I have a few bottles of the old Tamiya Clear paints.
Red, Green, and Yellow... That is what I used to paint all my bulbs with to get them
colored. Succesive coats of the gel would make the bulb look almost black, but
when lit at night, the colors were perfect.
Last edited by Umi_Ryuzuki; Feb 03, 2008 at 05:32 PM.
Feb 05, 2008, 12:51 PM
Registered User
If the big one is a robbe floodlight, what the hell are the smaller ones?

self design?
resin duplicates?
I became desperatet searching for some 1/50 floodlights..

If you have seen it on my album, my floods are made of brass with 2 SMT LEDs in. Each of the LEDs has 5 chips, so u can drive it with a max. of 100 mA. Lightenig angle is 180° (no lenses). Heat discharge is the main proeblem, therefore the LEDs are only driven by 40 mA with an integratet mosfet transistor.

In the meantime white LEDs are available in many colour variations. From cold to steal to bright to warm, sunny and gold...
I used the cold to build the neon-lights, and a "warm" version for the floodlights. But i allso used the Revell #730 clear yellow paint to put a dot on the lense of the LED. Be carefull, sometime the effect drifts to green or violett (depends on the spectrum of the LED) !

In a sense...
you should decide betweeen a day-lightening and one für the night...
If i drive my neons with 10 mA, it's ok for the day-lightening. You can detect that light is switched on, OK.
But for night operation, relation between the neons and floodlight is not correct, my neons had to be dimmed..

Where did you get this housings of the floods?

Feb 05, 2008, 03:10 PM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
Three of us have had the same issue with the Robbe Flood light,... it is really large.

So, I built one small master for the small flood light, made a mold and cast it a few times.
The pieces in the earlier picture are five castings, of the original, set up to make a mold for multiple castings.

With the larger mold, I can now take my clear resin, Fill the mold, vacuum de-air it to get the resin down into the detail. then push an LED into the resin and let it cure.
I get five floods a shot.

Your Abielle is beautifully lit. The attention to your lamp color/temperature does a lot toward creating a realistic presentation.
Feb 06, 2008, 01:54 AM
Registered User
I feared as much,...
nothing to buy at a store...

Your negative is a two-part silicon rubbber mold?

Think, i should make a molding too. This will not be my last floodlights in 1/50 i will need, and the methode i worked it for the "Abeille" is too expensive to build 10 or 20 of it.


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