chametzoo
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Post by chametzoo on Jan 22, 2018 23:15:27 GMT -8
Hi All, Like many of you, my '60 Mobile Scout has a storage bulkhead in the front of the trailer over a dining table with a globe light of some kind over the table. Recently, I added a dimmer to that fixture. I spliced the dimmer into the 12V supply leading to the fixture, inside the bulkhead cabinet. I'd like to add 2 small courtesy lamps [like these: www.vintagetrailersupply.com/Compact-Courtesy-Lamp-p/vts-898.htm], at each end of the bulk head to add some light in the corners. Question: If I splice into the 12V supply to the main globe light in 2 places, one for each added lamp, (with the crimp-on type splicers), will the 2 added lights also be on the main globe dimmer as well? (I only use LED bulbs, so the circuit can definitely handle the extra load.) |
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Post by vikx on Jan 22, 2018 23:50:30 GMT -8
Well, most trailers of this era had a 110 light under the bulkhead. If it had solid copper wiring, it is most likely not 12 volt. So, the dimmer may work at this point but I'd be very careful hooking anything else up unless you've removed the 110 system? (sorry, can't remember all everyone has done)
If it truly is a 12 volt light the other two should dim if wired correctly. Attach the dimmer to the main hot wire of the old light and wing nut (connect) the hots to the 2 courtesies at that connection. You should then be able to dim all 3.
I'm not really up on LED bulbs, be sure they are dim-able as well.
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charliemyers
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Post by charliemyers on Jan 23, 2018 5:47:16 GMT -8
If your lights are wired in parallel (as they should be....all of the +12V together and all of the grounds together), then I would think yes, all of them should dim. However I don't know that you can count on all of them shining at the same brightness level.
Without knowing more about your dimmer, the rest of this explanation is speculation. Although LED lights can be dimmed by varying the resistance, most often they're dimmed by "PWM" (Pulse Width Modulation - the light is turned on & off at a high frequency with the amount of "on" time versus "off" time being varied...the human eye sees it as either getting brighter or dimmer). Often the low side (ground) is switched on & off this way because the electronic components that switch the low side are typically cheaper and more efficient than those that switch the high side (+12V).
So if your dimmer accepts both +12V and ground wires and if it's designed for dimming LED lights, you will probably need to run both +12V and ground wires from the dimmer output to each fixture, and you may need to make sure that none of those three fixtures are grounded by any other way (otherwise a PWM on the ground wire will have no effect).
I'm usually not terribly good at explaining things, so I hope that makes sense.
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Post by Deleted on Jan 23, 2018 11:11:18 GMT -8
I personally thought this was an excellent explanation.
Question for Chametzoo that Vikx brought up. Did you confirm the supply wire to your globe fixture is 12V? If so, is it directly wired from a 12V battery, or is it a 110V supply run through a converter to step it down to 12V?
In some cases you might have both 12V and 110V supplied to the same fixture that has (2) bulbs so you can switch back and forth as needed. Also, I know they sell both 110V and 12V LED fixtures, so you want to confirm your LED fixtures match the voltage supply in your case.
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chametzoo
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Post by chametzoo on Jan 23, 2018 14:07:06 GMT -8
Well, most trailers of this era had a 110 light under the bulkhead. If it had solid copper wiring, it is most likely not 12 volt. So, the dimmer may work at this point but I'd be very careful hooking anything else up unless you've removed the 110 system? (sorry, can't remember all everyone has done) If it truly is a 12 volt light the other two should dim if wired correctly. Attach the dimmer to the main hot wire of the old light and wing nut (connect) the hots to the 2 courtesies at that connection. You should then be able to dim all 3. I'm not really up on LED bulbs, be sure they are dim-able as well. Thanks Vikx... My trailer was rebuilt in 2015, so it's primarily 12V and all the wiring is new and the system modernized fully, so that's not an issue. I'm thinking of trying what you suggest. Right now the existing globe light (12V LED) is wired with the hot passing through the dimmer like a switch would be. So, I'll first try connecting the hot wires from each of the new courtesy lights to the contacts on that same dimmer. I'm hoping it will both pick up the current and also provide the same dimming action as it provides to the globe. If that's the case, adding load to that particular fixture circuit will help give me more latitude in the dimmer adjustment range. Because I'm using LED in the globe and the load is therefore so low (4 Watts, I think), right now the dimmer is so darn sensitive that you just have to nudge it a degree or two and you get a noticeable change in brightness. We'll see how it goes. I'll mock up the connection first before I do any drilling to mount the fixtures. The idea with adding the courtesy's is just to throw a little light into the front corners of the dining area. The courtesy's will be mounted to the underside of the front bulkhead at either end and will let a little light spill downward, but most will bounce off the front indirectly (I'm a photographer, so I'm a stickler for light balance in interiors!). They do not come with a negative wire because I assume, when they are used in their normal context they will ground themselves to the trailer just by contact to metal. I guess I'll just solder a wire to the metal fixture housing. Whatchya think? |
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chametzoo
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Post by chametzoo on Jan 23, 2018 14:07:57 GMT -8
I personally thought this was an excellent explanation. Question for Chametzoo that Vikx brought up. Did you confirm the supply wire to your globe fixture is 12V? If so, is it directly wired from a 12V battery, or is it a 110V supply run through a converter to step it down to 12V? In some cases you might have both 12V and 110V supplied to the same fixture that has (2) bulbs so you can switch back and forth as needed. Also, I know they sell both 110V and 12V LED fixtures, so you want to confirm your LED fixtures match the voltage supply in your case. Confirmed... thanks. |
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chametzoo
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Post by chametzoo on Jan 23, 2018 14:19:11 GMT -8
If your lights are wired in parallel (as they should be....all of the +12V together and all of the grounds together), then I would think yes, all of them should dim. However I don't know that you can count on all of them shining at the same brightness level. Without knowing more about your dimmer, the rest of this explanation is speculation. Although LED lights can be dimmed by varying the resistance, most often they're dimmed by "PWM" (Pulse Width Modulation - the light is turned on & off at a high frequency with the amount of "on" time versus "off" time being varied...the human eye sees it as either getting brighter or dimmer). Often the low side (ground) is switched on & off this way because the electronic components that switch the low side are typically cheaper and more efficient than those that switch the high side (+12V). So if your dimmer accepts both +12V and ground wires and if it's designed for dimming LED lights, you will probably need to run both +12V and ground wires from the dimmer output to each fixture, and you may need to make sure that none of those three fixtures are grounded by any other way (otherwise a PWM on the ground wire will have no effect). I'm usually not terribly good at explaining things, so I hope that makes sense. Charlie... I do follow you, thanks. I think my electrical system is good to go regarding all your concerns. The trailer is old in name only (1960) but all the systems are completely redesigned to my specs (in 2015), including the mostly 12V wiring. I've been using that dimmer on the table globe light (12V and LED) successfully for about a year now. The only caveat is what I stated in my response to Vikx regarding the very low load of the LED bulb in the globe and the very fine sensitivity of the dimmer. It's specifically designed for 12V, but is rated for standard tungsten bulbs of higher wattage apparently. I think that's where your PWM dimmer would come in handy. But I've learned to adjust things carefully with just a nudge of the dimmer dial to effect change in brightness. Your last concern regarding accidental grounding: the new lights will be mounted in wood on the underside of the front bulkhead... and besides, I'm apparently not using a PWM. |
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Post by vikx on Jan 23, 2018 22:27:21 GMT -8
Is there room to rivet a ground wire onto the courtesy light? It can be pretty small.. then you could solder as well.
I like the fact that you are so interested in lighting! Very important and we can learn from you.
Let us know how things go.
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charliemyers
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Post by charliemyers on Jan 24, 2018 7:51:06 GMT -8
Sounds like it's a rheostat type dimmer? If so then it's basically a variable resistor which drops more or less voltage across the resistor as you adjust it. LEDs require a very specific voltage to turn on, and they typically go from off to near full brightness in short order with this method which explains the very fine sensitivity that you're seeing.
Accidental grounding wasn't really a concern (the word "safety" usually comes to my mind when I hear "concern" as it relates to electricity). I primarily just wanted to point out that if you had a PWM controller (which apparently you don't) then it likely would not dim the LEDs if they had another path to ground.
I'm in the very beginning stages of designing my own PWM LED controller that can be controlled via wifi. Unfortunately I haven't had a whole lot of time lately to put into that project.
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chametzoo
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Post by chametzoo on Jan 24, 2018 9:25:44 GMT -8
I like the fact that you are so interested in lighting! Very important and we can learn from you. Let us know how things go. I'm like that at home too! For work, I shoot architecture and interiors, so with interiors I have to suit the lighting to the camera sensor in terms of relative brightnesses and color temperature. Also satisfy an aesthetic vision as well. Because of that, it's often a “translation” process from what your eye perceives to what the camera sees and records. I used to bring lots of lighting equipment with me to assignments, but now I've developed techniques in post production (i.e. Photoshop) that can handle some of that translation. Same objective, different method. Not quite relevant to vintage travel trailer interior lighting, but I like to build up a lighting scene with some even ambient light, but mostly smaller pools of light. In older trailers, it highlights the nicer materials like wood, stainless, aluminum, colored laminate. So that's what I did with my lighting when the Mobile Scout was renovated. Even with “warm” LED's, the color temperature cannot fool your eye into believing that it's a tungsten light. The color wavelengths of burning tungsten are so specific and the eye is so sensitive and conditioned to that color wavelength, that the warm LED's just tend to look like pure yellow. So, in the trailer, I actually “gelled” (translucent, colored photographic acetate) and diffused some of my light fixtures in order to produce a more familiar and real sense of actual tungsten (but with 1/10th the power consumption!). At the table and in the bunk area... more warm and “tungsteny”.... cozy. Over the kitchen sink and counter... a whiter, brighter, diffused light.... work area. These are the light characteristics we (of a certain age) were used to seeing in our living environments. Now, modern lighting has become quite homogenized in terms of color. LED is a wonderful thing, but the makers and the lighting designers have to work on “tuning up” the color temps. With LED it's possible; you can create ANY specific color wavelength you want. More than you wanted to know!  Here are some examples of my work: www.michaelmatsil.com/ARCHITECTURE/buildings/1 |
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chametzoo
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Post by chametzoo on Jan 24, 2018 9:32:16 GMT -8
Sounds like it's a rheostat type dimmer? If so then it's basically a variable resistor which drops more or less voltage across the resistor as you adjust it. LEDs require a very specific voltage to turn on, and they typically go from off to near full brightness in short order with this method which explains the very fine sensitivity that you're seeing. Accidental grounding wasn't really a concern (the word "safety" usually comes to my mind when I hear "concern" as it relates to electricity). I primarily just wanted to point out that if you had a PWM controller (which apparently you don't) then it likely would not dim the LEDs if they had another path to ground. I'm in the very beginning stages of designing my own PWM LED controller that can be controlled via wifi. Unfortunately I haven't had a whole lot of time lately to put into that project. Yes... rheostat. Your WiFi controlled PWM sounds interesting. Once you've developed the hardware, you can create the “App” for remote use through smart phones. |
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charliemyers
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Post by charliemyers on Jan 24, 2018 11:11:20 GMT -8
Actually I do intend to use a smart phone for the interface. The microprocessor that I'm using can run its own little web server, so I might be able to make it OS independent and require only a web browser. But I haven't decided yet whether to go with a purely web based solution or develop an app (I have zero experience writing apps). I still have some details to work out with the hardware though before moving on to the software.
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Post by Deleted on Jan 24, 2018 11:25:13 GMT -8
charliemeyers...you are hired! This is what I'll be looking for when resto-modding my Catalina.
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chametzoo
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Post by chametzoo on Jan 24, 2018 12:16:53 GMT -8
Actually I do intend to use a smart phone for the interface. The microprocessor that I'm using can run its own little web server, so I might be able to make it OS independent and require only a web browser. But I haven't decided yet whether to go with a purely web based solution or develop an app (I have zero experience writing apps). I still have some details to work out with the hardware though before moving on to the software. I suggest you check out what already exists in lighting and general house systems management apps... 'cuz phone apps and mobility are the way to go these days for that kind of application. If you're just developing this for yourself, then do what suits you of course. But it all sounds very kool! |
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Post by kathleenc on Jan 24, 2018 13:07:23 GMT -8
If this is what "simple 12-volt wiring" discussion is like, I am even dumber than I thought!
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Here are some examples of my work: 