chametzoo
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Post by chametzoo on Apr 6, 2017 17:42:31 GMT -8
I have a light fixture in my trailer that I would like to add an in-line dimmer to. The 12V LED bulb is designated as “dimmable”, as some LED's are not. My trailer is primarily wired 12V (with a Progressive Dynamic converter for when plugged into shore power). But in any case, it's always 12V coming to the fixture and the LED dimmable bulb is of course 12V. Can I use a standard rotary rheostatic (variable resistance) dimmer like one would use with standard tungsten bulbs?
Any advice from the 12V electrical buffs out there would be appreciated.
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mrmarty51
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Post by mrmarty51 on Apr 6, 2017 18:15:17 GMT -8
Might install a headlight switch from an old Chevrolet, just pull to park light position then twist. LOL I just had to do that. I dont know what else a person would use.
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chametzoo
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Post by chametzoo on Apr 6, 2017 18:33:24 GMT -8
Might install a headlight switch from an old Chevrolet, just pull to park light position then twist. LOL I just had to do that. I dont know what else a person would use. Thanks Mr.M. But the question is, whether any standard rheostat is compatible with LED type bulbs.
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Ten
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Post by Ten on Apr 6, 2017 19:01:14 GMT -8
That ^^ may well be your answer. They have made the dash lights dim for decades in autos. A standard dimmer certainly seems like it should work fine.
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mrmarty51
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Post by mrmarty51 on Apr 6, 2017 19:10:40 GMT -8
Might install a headlight switch from an old Chevrolet, just pull to park light position then twist. LOL I just had to do that. I dont know what else a person would use. Thanks Mr.M. But the question is, whether any standard rheostat is compatible with LED type bulbs. I dont know if a standard wall dimmer switch for the 110 circuitry would work with as low of a voltage draw as what the LEDs draw. A person could buy a dimmer switch and try it. That ^^ may well be your answer. They have made the dash lights dim for decades in autos. A standard dimmer certainly seems like it should work fine. YUP, I was being serious, I would have to call it the cool factor to have an old vehicle light switch to control the LEDs with. LOL I would think that the compactness of the headlamp switch would be nice too.
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chametzoo
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Post by chametzoo on Apr 6, 2017 19:31:30 GMT -8
That ^^ may well be your answer. They have made the dash lights dim for decades in autos. A standard dimmer certainly seems like it should work fine. But they're not LED. That's the issue here.
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Ten
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Post by Ten on Apr 6, 2017 19:34:34 GMT -8
Understood, but I would think a replacement conversion auto bulb should be able to function as the originals...but I cannot answer for sure. That is just my logic.
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mrmarty51
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Post by mrmarty51 on Apr 7, 2017 0:36:32 GMT -8
A dimmable LED is a dimmable LED, Long as it is 12 volt, what would the difference be. As long as it doesn't draw so many amps that it would burn out the rheostat, which I highly doubt.
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chametzoo
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Post by chametzoo on Apr 7, 2017 10:30:29 GMT -8
A dimmable LED is a dimmable LED, Long as it is 12 volt, what would the difference be. As long as it doesn't draw so many amps that it would burn out the rheostat, which I highly doubt. Hmmm… maybe I'm making something over nothing. Wouldn't be the first time . Just tested a standard LED household bulb with a standard “touch dimmer” (you screw it into the lamp socket, then the bulb into the touch dimmer, and the bulb dims in three stages when you touch a metal part of the lamp). The bulb dimmed just as it's supposed to. No problem!
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mrmarty51
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Post by mrmarty51 on Apr 7, 2017 11:03:14 GMT -8
Thats good news. I really do not see what a standard household rotary dimmer would not work, except their so big for such a small space. LOL
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cowcharge
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Post by cowcharge on Apr 7, 2017 15:15:13 GMT -8
I'm wondering if there would be any bad effect from the big difference in current draw between the two bulbs. A regular 12v bulb draws about 2 amps, while the LED is probably about 1/10 of that. It wouldn't take much of a wire run for voltage drop to start gettin' ya, and a rheostat is adding a whole lot of wire length. Like maybe the whole dimming range will be used up by three degrees of knob-turn. At any rate, I think I'd look for a 12-volt dimmer like the headlight switch, rather than a house dimmer. FWIW, I did a quick google search and found this thread about dimmers and power savings. diy.stackexchange.com/questions/11747/when-i-turn-down-the-dimmer-switch-on-my-lights-do-i-actually-use-less-electricOne commenter wrote: "Dimming LED are easy but to get the best dimming experience you will need a dimmer designed for LED's. These have what I used to call a trim screw so you can adjust the dimmer to use the whole dimming range. Trim screws were used for fan speed controls and you would adjust the trim screw down to where the fan is spinning when the speed control is turned to the lower setting."
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mrmarty51
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Post by mrmarty51 on Apr 7, 2017 15:28:51 GMT -8
I'm wondering if there would be any bad effect from the big difference in current draw between the two bulbs. A regular 12v bulb draws about 2 amps, while the LED is probably about 1/10 of that. It wouldn't take much of a wire run for voltage drop to start gettin' ya, and a rheostat is adding a whole lot of wire length. Like maybe the whole dimming range will be used up by three degrees of knob-turn. At any rate, I think I'd look for a 12-volt dimmer like the headlight switch, rather than a house dimmer. FWIW, I did a quick google search and found this thread about dimmers and power savings. diy.stackexchange.com/questions/11747/when-i-turn-down-the-dimmer-switch-on-my-lights-do-i-actually-use-less-electricOne commenter wrote: "Dimming LED are easy but to get the best dimming experience you will need a dimmer designed for LED's. These have what I used to call a trim screw so you can adjust the dimmer to use the whole dimming range. Trim screws were used for fan speed controls and you would adjust the trim screw down to where the fan is spinning when the speed control is turned to the lower setting." They plumb lost Me when they put alphabits into the math equations. LOL Like the dimmer description says. if You have a hundred watt bulb, You dim it by half, 50 watts is going to the bulb and 50 is being burned in the resistor. Albeit that LEDs do not use any where that amount of power, there would be no danger of causing a fire from what would be burned in the resistor. I dont think. I do like the concept of the dimmer switch that flashes the bulb on and off thousands of time a second. That dimmer would be the real cats meow.
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cowcharge
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Post by cowcharge on Apr 7, 2017 15:35:56 GMT -8
LOL yeah, I didn't have the patience to work out the formulae, especially since they were talking power savings, and it wasn't 12 volt stuff either.
I dunno, some people are disturbed by the 60-cycle flicker of fluorescents, and according to one of the guys in that thread, the dimmers only cycle 120 times per second, not thousands.
Time to experiment I guess, if budget and time permit.
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chametzoo
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Post by chametzoo on Apr 7, 2017 19:00:52 GMT -8
I'm wondering if there would be any bad effect from the big difference in current draw between the two bulbs. A regular 12v bulb draws about 2 amps, while the LED is probably about 1/10 of that. It wouldn't take much of a wire run for voltage drop to start gettin' ya, and a rheostat is adding a whole lot of wire length. Like maybe the whole dimming range will be used up by three degrees of knob-turn. At any rate, I think I'd look for a 12-volt dimmer like the headlight switch, rather than a house dimmer. FWIW, I did a quick google search and found this thread about dimmers and power savings. diy.stackexchange.com/questions/11747/when-i-turn-down-the-dimmer-switch-on-my-lights-do-i-actually-use-less-electricOne commenter wrote: "Dimming LED are easy but to get the best dimming experience you will need a dimmer designed for LED's. These have what I used to call a trim screw so you can adjust the dimmer to use the whole dimming range. Trim screws were used for fan speed controls and you would adjust the trim screw down to where the fan is spinning when the speed control is turned to the lower setting." Hey Cowcharge… was wondering when you would chime on this . I have my eye on this particular low voltage dimmer: www.ledlight.com/dimmer_low_voltage_one_channel_8a_12vdc_96w.aspx?gclid=CNXqpvaljtMCFUuUfgodu2IO_A. I will be using it to dim my over the dinette table light fixture, which will be fitted with this dimmable 5W 12V LED bulb. It says that it is dimmable to 90% with a “magnetic low voltage dimmer”: www.lampsplus.com/products/5-watt-12-volt-candelabra-led-light-bulb__6y942.html I'm not trying to save electricity in this case, but rather provide some lower light ambiance (for those romantic trailer dinners ). Might this combination work?
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cowcharge
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Post by cowcharge on Apr 9, 2017 5:54:59 GMT -8
Haven't been around much, which is why I'm silent for a month and then respond to twenty threads on the same day. I try to chime in only if I know something, but sometimes I like spitballing too, like here. I'm no electrical engineer. In fact, I did only one year in engineering in college before I switched to journalism, lol. I was great at math until I hit Calculus, which was incomprehensible to me.
My comment was based at least as much on my perpetual lookout for Murphy to come enforce his law than on any knowledge of dimmers. The one you linked to says it's good for any load less than 8 amps, so it sounds like it ought to work. But I don't have enough knowledge of dimmers or all the needs of all the different LED bulbs to definitely confirm it.
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