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AC or DC LED's


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Not actually a LOR question but I've apparently been educated and don't know why.  Hoping some electronic experts here can help out.  Just finishing a landscape project and purchased some small 3W LED spots on ebay for $6 sans power supply.  from China of course, and marked AC DC 12v.  I assumed that just meant plug it in to AC, convert it down to DC 12V like I'm used to doing with electronics.  I had a landscaping power supply, 300W that I thought put out 12VDC until I metered it.  It's 12VAC.  The lights work fine on AC and that's my point of confusion.  I know I have 5M LED strands that are 120VAC and an RGB star that's either 5VDC or 12VDC, I forget which.   I had no idea that an LED could operate on either type of voltage.  How is that possible?




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Here is the listing..................


Power: 3W (3*1W)
Materials: Aluminum
Voltage: AC/DC 12V; AC/DC 85-265V
Lumens: 300-330 LM
Beam Angle: 60 Degree
Color: Warm white(2600-2800k); 
            Cool white(6300-7000k);
Waterproof Rating: IP65
Size: 43x65x89mm
Connecting Wire Length: 30cm
Life Span: 100000 Hours
Approval CE/RoHS approved 
Low heat, no UV or IR light radiation.
Environmental-friendly and energy saving.

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LEDs will be happy to work on either AC or DC current provided its the correct voltage. But when connected to AC they're only being lit half the time giving them a slight flickering affect that is not that noticeable to the human eye. I try to install a rectifier whenever I can to convert the AC to DC. This makes them look brighter and a little more pleasing to the eye.

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I have bought 10w rgb floods online and they had an a/c to 12v d/c converter inside the light fixture. So you just plug in 110v and they convert to 12v. If you want to control them through LOR you re move the converter from inside and use cmb 24d or other controllers. there are post on here all about converting these lights to work with LOR.

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Can LEDs run off AC power?

Not directly. The voltage required to run an LED is typically between 3 and 4 volts DC (about the output of 2 household batteries). Furthermore, LEDs are polar devices which means that they only conduct current in one direction. In order to operate LEDs from AC power, a converter circuit, called a driver is required. This driver converts the high AC voltage to a lower DC voltage with a constant current.

It should be noted that there are some “so-called” AC LEDs but these are basically LEDs configured as a rectifier to allow connection directly to the AC line. The other limitation for “AC LEDs” is that they only emit light when current is flowing in one direction, and therefore, only output 50% as much light.

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I skipped over the other replies. Have you ever heard of a bridge rectifier? What happens if you apply AC to it. What about DC applied to the input? What is the difference to the output of the bridge rectifier. What if you reverse the DC to the input of the bridge?


Now for your ah ha moment.

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