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Post by tomten on Apr 12, 2017 12:58:31 GMT
Hiya,
I'd like to install some dimmable LED reading lights in master bedroom. I am happy to go with a proprietry unit, or make something up myself, but I am struggling to find anything appropriate.
I like to think I understand the electrical side of most things, but am a bit lost here... Almost all low voltage LED kit seems to be sold on the basis that it will be installed in a house, and used with a low voltage transformer and a dimming controller. Can I just use any controller (assuming appropriate input voltage), and skip the transformer out of the equation and just feed DC direct from my batteries? Is there a simpler way, like a variable resister pot in line with the bulb???
Any clues or pointers welcome.
FYI I am on 24v, but I will be running a 12v step down for computer chargers, and could tap into that if necessary.
All other fittings on board so far are MR16 and MR11, so would like to keep with this theme.
Ideally I will find a bendy gooseneck type lamp.
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Post by lollygagger on Apr 12, 2017 13:04:25 GMT
Yes you can get 12v led dimmers but the only ones I've found in the past are a bit awkward and need fitting through a thin cover plate (not included or offered).
Both + and - need wiring through the dimmer, that caught me out in a vehicle but won't be a problem in a boat.
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Post by lollygagger on Apr 12, 2017 13:05:58 GMT
I've also seen flush light units with touch dimming built in. All well and good if they're in easy reach.
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Post by Telemachus on Apr 12, 2017 14:22:34 GMT
So being technical about it, many LED bulbs (but not all) have voltage stabilisation (SMPS) in them. They don't work well with just reducing the voltage, or at least the dimming will occur over a pretty small voltage range and it may well flicker. If it is a bulb just with resistive current control (ie specced only at 12v, rather than something like 9 to 30v) then a variable resistor in series will work reasonably well but it will dissipate quite a bit of power (depends on the power of the LED bulb of course!) and so will need to be physically fairly large and will get hot. A better solution for a resistive type LED would be one of the cheapo adjustable switch mode power supplies from ebay. They tend to have trimpots to set the voltage but you could perhaps unsolder that and solder in a normal potentiometer - probably need to keep the wires fairly short though. You could put a fixed resistor in series with the potentiometer +ve to limit the maximum output voltage to 12v and then run the power supply direct from the 24v killing 2 birds...
LED dimming is best done by PWM ie switching the supply on and off at a variable ratio, 100 times a second or more. This is how we dim the LEDs on our boat and it works fine with various different types of LED bulb (some resistive, some SMPS), but then we have a computer controlled electrical distribution system (Empirbus). There may be such a thing (ie 12v PWM dimmer) available for consumer use but I've never used one.
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Post by lollygagger on Apr 12, 2017 14:46:56 GMT
Yes you can get PWM dimers for LEDs on eBay for a few quid. Remote ones too.
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Post by Telemachus on Apr 12, 2017 15:19:08 GMT
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Post by lollygagger on Apr 12, 2017 15:45:21 GMT
The first one I've used because I couldn't find anything else. Functional would be polite as they do work but that's your lot! |
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Post by Jim on Apr 12, 2017 15:58:17 GMT
Lidl recently had bendy Swan neck led fittings with transformer. I checked output on transformer, 12v, so bought it and cut the 12v feed wire. It had a wall mounting plate at the end. Next lidl I went in had 3 more, this time with a clamp mount.
They were all £6 each, in the cheap bin!
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Post by tomten on Apr 14, 2017 18:15:33 GMT
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Post by lollygagger on Apr 14, 2017 18:27:04 GMT
I wondered about that, but though there isn't a click, off is off, I didn't have a seperate switch. |
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Post by Jim on Apr 15, 2017 7:55:51 GMT
Was looking for led replacement bulbs, came across some touch to dim ones, various fittings, 1 touch, on,two dim. Google is your friend.
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Post by tomten on Apr 15, 2017 8:39:08 GMT
I wondered about that, but though there isn't a click, off is off, I didn't have a seperate switch. Hmmm. So, thoughts on this? Would be much better to have single dimmer feeding multiple separately switched lights. Dimmer would then remain set at desired brightness. Would dimmer be drawing power from batteries, even when lights were switched off? |
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Post by lollygagger on Apr 15, 2017 8:40:46 GMT
No, switched off is switched off.
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Post by windrush on Apr 15, 2017 10:27:03 GMT
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Post by tomten on Apr 15, 2017 13:15:54 GMT
Hey, not what I am looking for, but interesting nonetheless! |
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