(To Martin Brown) The OP, by the way, is involved in a volunteer run tramway/ railway in foreign parts, and has previous form for asking questions by giving us the full information drip by painful drip, so we have to guess what his actual problem is until the last moment. I'm not sure why he does this, but that's life.
I think I worked out the name of the place in the past so:-
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He seems paranoid about people from that organisation reading this group and trying to work just what he's trying to get away with *this* time.....
Yes I think something like this is what I will buy. The only remaining prob lem is that I will have two lights and two remotes. I assume that if I pres s red on one remote, both lights will change to red, when of course I want the remotes to operate one light only. But since the bulbs will be mostly i n a Faraday cage, the remote will have to be in front of a lamp for it to w ork.
alf of them red and half white (or yellow). I'll switch on the different co lours separately. And I want a diffuser over them so they don't look like a pile of LEDs.
r oyur local theatre supplier for a riffle through the gel books.
I'm about to purchase some RGB LED bulbs. I want to cover them with somethi ng like gas mantles, but the bulbs are quite large and mantles are too frag ile anyway. I was thinking of putting loose weaved fibreglass cloth around the bulbs. Unless anyone has a better idea.
In the original post you indicted that you wanted light in 360 degrees. In later posts it was implied that the light would be used in a spotlight type fashion requiring a beam angle of possibly less than 90 degrees (the linked LEDS have a viewing angle of 45 degrees). In the original post the request was for solutions for red OR white - not both together but now it appears that red and white need to be on together.
Red or White is one lamp and one remote.
If you have two lights, one each end of the vehicle, then it should not be a problem. You would have to be facing the front of the lamp for the remote to work, as you have suggested. The problem is not the Faraday cage but the remote is Infra Red light and the only place the IR light can enter the bulb is is by way of the same place that the lights exits the bulb. The remote has a relatively short range.
If you now cover the bulb with a gas mantle or fibre glass the remote will not work.
Be aware also that there is a good reason why the bulbs have metal cases
- they need a substantial heat sink and a fitting that can provide a lot of free air ventilation and/or a fitting that can connect to the metal to provide an additional heat-sink.
Other products such as colour changing floodlights may offer better possibilities: The LED can be easily removed and screwed directly to a large piece of metal as a heat-sink. The remote sensor is separate and the connection wires extended so it can be mounted external to the light fitting. The downside with this approach is that some electronics knowledge is required and maybe that the flood light control circuits don't run from 12V.
Another alternative is something like
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Data sheet shows typical resistor values Similar products available elsewhere/ higher wattage devices also available. A cheap source may to be to buy a colour changing floodlight and just use the LED.
12V supply, a few power resistors bolted to a heat-sink, the LED bolted to a substantial heat-sink and a few switches. The heat sink could be the back metal panel of the light. For white switch on all LEDs, for red just switch the red LED. You may have to tweak the resistor values for green and blue to get the the white light. This is a low tech approach and not that efficient on overall power.
At each end of the vehicle there is a two foot diameter reflector. The forw ard end has to have a white light and the rear light has to be red, then th e colours have to be swapped over when the vehicle is moving backwards:
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In the above photo there is an ordinary incandescent bulb around 60mm in di ameter. This sends light backwards and sideways into the reflector, and a b it out the front. However the effect I want to see is a two foot diameter c ircle of light shining forwards, not just a little bright spot in the middl e. All of the LED bulbs and LED spotlights I have seen will not shine backw ards into the reflector, so are no good. I'm now leaning to the idea of wrapping an LED strip around a copper or bra ss tube. If I wrap both a white and a red LED strip, that is very easy to c ontrol with a simple switch. If I use an RGB LED strip I will need two cont rollers. Since those can be some distance away from the LEDs they will work if the LEDs are covered by mesh. Those particular controllers are IR, but others are radio frequency hence t he problem with accidentally switching both lights at once. However using no controllers is easier and cheaper, so I think I'll go with that.
rward end has to have a white light and the rear light has to be red, then the colours have to be swapped over when the vehicle is moving backwards:
diameter. This sends light backwards and sideways into the reflector, and a bit out the front. However the effect I want to see is a two foot diameter circle of light shining forwards, not just a little bright spot in the mid dle.
2`makes it easy, LED tape stuck on to an alloy backing plate in strips.
Either alternating red and white strips or RGB and mix to what will always be a cold white.
LED tape is generally 10mm widede so get plenty of strips, 12v tape will cu t every 3 LEDs, on a 600mm plate. Looking for 5050 LEDs and at lest 60 per meter, 300 per 5m spool.
Depending of density in diffuser anything more than about 50mm from LEDs to diffuser should begin to look reasonably even.
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l/supergel-diffusers.htm
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ds into the reflector, so are no good.
rass tube. If I wrap both a white and a red LED strip, that is very easy to control with a simple switch. If I use an RGB LED strip I will need two co ntrollers. Since those can be some distance away from the LEDs they will wo rk if the LEDs are covered by mesh.
the problem with accidentally switching both lights at once.
To achieve the effect you are looking for you probably need a very bright point source pointing backwards into the reflector which suggests a single LED or LED RGB array of many watts.
This LED would need to be mounted at the same point as the element of the existing light bulb.
The optical properties of the reflector are the important points to consider for your modified design. If you change a point source (the incandescent bulb) for multiple point sources (multiple LEDs spaced far apart) you may not get the effect you want
Depending on how the existing bulb is mounted, the the LED could be screwed to a straight or L shaped brass, aluminium or copper bar - used as the heat-sink.
You could use a backward facing LED with a beam angle of, say, 140 degrees to hit the reflector and a second forward facing LED with a beam angle of less than 10 degrees (obtained with a lens)
Could you mount the red filter in a shutter like an Aldis lamp? Then all anybody would need to do is turn a lever to close the shutters, to put the red filter across the light, or to open it, to allow the white light to shine between the shutters.
Yes that would work OK except there's not a lot of room inside the headlamp so it would have to go outside. Maybe when we get oil lamps I'll do that. In the meantime I have found some very cheap LED strip. I'll even use that for my emergency lighting in my house.
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