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Post by danrhodes on Apr 9, 2017 9:48:41 GMT -8
I would stick with the recommended magnetic LV dimmer. A pwm style like your link will probably work fine, and is the type I would use for a fan control, but may result in flickering or "shimmer" of the led output. You can get MLV dimmers at most home improvement stores.
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chametzoo
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Post by chametzoo on Apr 9, 2017 12:44:54 GMT -8
I would stick with the recommended magnetic LV dimmer. A pwm style like your link will probably work fine, and is the type I would use for a fan control, but may result in flickering or "shimmer" of the led output. You can get MLV dimmers at most home improvement stores. Dan… the ones at the home improvement stores are usually for 120V household. Is that a factor here? Can I use that with a 12V system? Thanks.
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Post by danrhodes on Apr 9, 2017 14:24:46 GMT -8
Hmmn...I think I may have steered you wrong here...those candelabra bulbs seem intended for 12v conversions, so you would have a transformer that the 120v MLV dimmer was connected to. For direct DC applications, I don't know if an MLV will work properly and you may need to use the type of pwm dimmer you linked to. For guinea pig stuff like this I always buy at home Depot so I can easily return. www.homedepot.com/p/Armacost-Lighting-2-in-1-White-LED-Dimmer-DIM2IN1-96W12V/203227246
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chametzoo
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Post by chametzoo on Apr 9, 2017 16:00:06 GMT -8
Hmmn...I think I may have steered you wrong here...those candelabra bulbs seem intended for 12v conversions, so you would have a transformer that the 120v MLV dimmer was connected to. For direct DC applications, I don't know if an MLV will work properly and you may need to use the type of pwm dimmer you linked to. For guinea pig stuff like this I always buy at home Depot so I can easily return. www.homedepot.com/p/Armacost-Lighting-2-in-1-White-LED-Dimmer-DIM2IN1-96W12V/203227246Dan. Thank you. I think you may have “cracked the code” on this particular issue: This is a direct DC application (although when the trailer is connected to 110V shore power, the current is converted down to 12V by a Progressive Dynamics converter… not sure it that matters in this case). The low voltage dimmer you specified from HD, is not available from my local store, so it would still be a mail order purchase… so I'll probably go with the one I linked to since it so cheap. The HD one and the one from LEDlight.com appear to be for the same applications. The best thing to do at this point is to get the bulb, the low voltage dimmer and set it up and see if it works.
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chametzoo
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Post by chametzoo on Apr 17, 2017 12:46:04 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. As usual, Cowcharge knows what he's talking about. I got my 12V rotary dimmer and my dimmable 12V LED bulb. Wired in the dimmer before the light fixture. Because of the difference in bulb draws between a 12V tungsten and a 12V LED (the amp draw of this 5W bulb is about .2 amps) most of the dimmer rotation range (more than 95%) is useless; the light just stays full bright as you rotate it down. But it does work when you get to that last couple of degrees of rotation as Cowcharge noted. You have to be super, super gentle with it and it will nicely dim the bulb down across a range of brightness. But you have to be very precise though… a matter of millimeters! I will definitely have to be the one in charge of that switch! This particular dimmer was rated <8 amps / <96 watts… But I wonder what dimmer there is out there that would work “normally”, with full rotation/dimming range for this kind of very low amperage/wattage 12V application??? For now, I can work with this one and it is doing what I want it to… although oddly.
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cowcharge
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Post by cowcharge on Apr 19, 2017 9:30:03 GMT -8
LOL lucky guess. And it wasn't exactly what I was thinking, so don't give me too much credit.
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chametzoo
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Post by chametzoo on Apr 19, 2017 15:15:25 GMT -8
LOL lucky guess. And it wasn't exactly what I was thinking, so don't give me too much credit. Let's call it an “educated” guess But it would still be nice to know what type of dimmer would give you a more normal rotation control with these super low draw bulbs. But regardless I got something that works.
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cowcharge
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Post by cowcharge on Apr 19, 2017 20:15:28 GMT -8
I wonder what one of these R/C boat resistor-type speed controllers would do if you hooked it up to a bulb... It has forward and reverse so it would be off in the middle and bright at both ends. Expensive experiment, though. www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXE528Speaking of rheostats though, my brother made one for a model ship out of a screen door spring with a sliding contact.
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Post by danrhodes on Apr 19, 2017 20:37:58 GMT -8
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