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Summary:

  • Are there LED Dimmers that are "always on" and whose settings survive loss of power?

Details:

I am considering a more or less standard led-strip set (consisting of power transformer/driver, dimmer/controller and led strip) for installation behind a mirror in the toilet. I need the dimmer only to set the desired brightness once. After initial setting, it will be sitting behind the mirror, and dimming should be constant. No remote control is needed.

The LED set will be mounted where there used to be a standard 220V light bulb. The 220V driver of the LED set would be turned on/off using the existing 220V light switch on the opposite wall.

This leads to my issue: the dimmer/controller should automatically come back on after loss of power. Also it should preserve its dimming setting.

  1. Does this exist? All controllers I've found have an on/off switch or come with a remote control, which makes me fear they will be off after loss of power.
  2. Does this depend on the brand or type of controller? I couldn't find any documentation on this. Is there a specific term I should be looking for?
  3. Can you name a few brands/types that provide this behavior?
  4. Is this "good practice"? I don't see direct alternatives due to existing cabling in the wall.

Thanks for any insights.

** edit ** this is for 12V or 24V, white led strip (about 1.5 meter)

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closed as off-topic by Chris Stratton, RoyC, DoxyLover, Elliot Alderson, Sven B Dec 6 '18 at 5:59

This question appears to be off-topic. The users who voted to close gave this specific reason:

If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    \$\begingroup\$ I'm voting to close this question as off-topic because the selection of consumer product modules, electrical appliances, etc and their behavior is off topic here. Aspects of the the design of an original device to solve this problem could be on topic, but that is not what you are asking about, nor is it likely the best way to solve your problem. EESE is not the place to find out what is available on the lighting market and how it behaves. \$\endgroup\$ – Chris Stratton Dec 3 '18 at 21:00
  • \$\begingroup\$ move to Home improvement \$\endgroup\$ – Sunnyskyguy EE75 Dec 3 '18 at 21:26
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You don't give any info about the LED strip, so I'll assume 12V and less than 2Amps.

The simplest solution would be to use a power supply which supports dimming by resistor, for example this one. Check out page 4. You need to order the correct version which is dimmable by connecting a potentiometer or a fixed resistor between the two DIM wires. It's really simple.

This kind of power supply behaves either as a constant current or constant voltage source. When using the dimming feature it will regulate current but the output voltage will not exceed 12V which is what you want. These cost about 20 bucks, which is pretty cheap and makes it not worthwile to roll your own.

If you forgot to mention that your LED strip is actually RGB, that won't work though.

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A classic leading-edge phase controlled Dimmer i.e. electromechanical Pot and Triac

It does this with push on-off and turn to set for any dimmable PAR LED lamps or similar dimmable LED lamps. This is what I use. I also have the linear slider types with built-in rocker switch.

Some high power dimmers leak or may not dim to <20% with higher impedance LED loads, but that should not be an issue.

Otherwise the more expensive types with staircase dimming need non-volatile voltage backup for either brief periods or extended shutdown depending on the method used (Supercap or battery).

The fanciest might include a motion detector that ramps up or down depending on direction of motion until it detects a rapid hand wave to ramp up or down to a different setting by wave toggle with a lithium cell battery for storing the intensity in RAM.

In your case, the 220Vac LED lamp switch does not require a dimmer with a switch unless you want it.

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