I bought a fairly cheap LED tape kit that comes with a driver and dimmer. The dimmer is a small inline module that sits between the driver and the LED tape.

The driver has 12V/2A output and is integrated into a horrible, black moulded plug. I want to replace this with a standalone driver and implement some nicer cabling. I don't see anything on the driver unit that indicates any kind of "dimmable" compatibility.

My question is whether the dimming compatibility is handled purely between the dimmer and the LEDs? Can I swap out the driver with any 12V/2A replacement?

  • It's constant-voltage 12 volts. It's not a driver, it 's a power supply. A driver is for certain constant-current LEDs which need that, when you see a PS say 26-44 volts 1.4 amps, that's a driver. – Harper - Reinstate Monica Feb 4 '20 at 7:23

Be clear on the things which plug into AC power and the things which don't. The things which do, must be UL-Listed, or an equivalent testing lab such as CSA or ETL. These marks are absolutely useless: RoHS, CE, CCC, FCC.

There are actually 3 separate things here.

A generic 12 volt power supply.

Any common 12 volt, constant-voltage (i.e. normal) power supply will do. You can use a hacked PC power supply. A car battery. The output of a solar charge controller. A 12V battery charger. Eight D-cells. Whatevs. Doesn't matter.

This is not a driver. A driver is a special thing designed to drive individual LED emitters or strings of -- yeah, I can see where that would be confusing. LED drivers are used with raw LED emitters (i.e. the raw parts from Cree) which need to be driven at a specific, exact current (but voltage could vary all over the map). Drivers are used for appliance LEDs like you might find in an IKEA floor lamp where there are 18 LEDs that need to be driven at exactly 350ma at some voltage between 52 and 80 volts. That is not what you have. I'll discuss later how LED strips regulate current.

You just need any bog-standard constant-voltage 12 volt supply that come in an endless number of forms. In LED strips, the power supply has no role whatsoever in dimming. (actual drivers do, but as said, you can't use a driver.)

The dimmer (or if color, the controller)

This module takes power in from the 12V power supply, and outputs PWM power for a limited number of LED strips.

An interesting fact about these is the same unit can usually work in a 24 volt circuit (24 volt PS + 24V strips).

Now, if you need to drive more than 2 amps worth of LEDs (or whatever the dimmer's rating is), you can use its output as a signal instead, and feed it to an amplifier. Most amplifiers are 3-4 channel for color LEDs, but you can just feed all 4 channels with the same signal.

The LED strips proper

Remember what I said about drivers? Your strip is cuttable every 2 inches or so. Look closely at a single segment: you will find 3 LEDs and a mystery part. The mystery part is a resistor, and its job is to be a current-limiter; it's a very simple, passive version of a driver.

If it's that easy, why do the other ones use active drivers? Because they're driving the LEDs very hard, as close to the manufacturer-spec redline as possible... which means, they must put large heat-sinks on the LEDs. These strips don't have heat-sinks, so they are driven at modest levels. This is less cost-efficient, but golly, you can hardly complain about the price.

  • Thanks for your thorough answer. Very interesting what you say about the power supply. I tried a regular 12V transformer and it certainly works. (And also with the dimmer as per my original question). This seems like a well kept industry secret, designed to fleece idiots like me. Tape manufacturers say you need a LED driver on the power supply, so does every electrical shop sales person. I'm curious, knowing this, would you perform a professional installation of LED tape with a bog-standard transformer, or would you go with the manufacturer's recommended unit even? – Tim Feb 4 '20 at 11:14
  • @Tim Yeah, lots of people do that thing I warned you about, which is using the word "driver" for a plain old power supply. I'm assuming by "tape" you mean common LED strips like are all over Amazon. Yes, any UL listed power supply that is 12V and puts out DC (not AC) and has >= the current draw of your LEDs will do the job. – Harper - Reinstate Monica Feb 4 '20 at 12:02
  • Yes the strips that come in reels. Not just the cheap Amazon ones, but also from well-reputed manufacturers like Aurora that sell wholesale to trade. – Tim Feb 4 '20 at 12:12

When you say “any” driver I would be cautious but it will probably work. A while back I had some led retrofit lights fail I figured out the needed voltage and it was 58v I thought what the heck I wonder if I put 2 in series and fed it with a simple full wave bridge that cost under a dollar if they would work (had a dozen of these cheap lights and all the drivers failed) I hooked them up on my work bench and except for the wire breaking off 1 time they have been running on rectified line voltage for over 6 months making my work bench quite bright.

The trick with leds is not to provide two much voltage, in the old days all the junctions were 1.2-1.7v and most burned up over 30-50 ma today the voltage range depends so your driver requires the proper voltage then to fully drive at max brightness the driver needs to be able to provide enough current.

Two low of a voltage and there will be no light no matter how much current the driver can provide.

Two high a voltage may fry the junction even if the current is below the max value so you get 1 flash.

If the voltage is right but the current is below the required value they may glow but not be bright.

Once you have the proper voltage a driver that can provide more power won’t be a problem as my example of the 2 lamps in series. However if I have a voltage spike on the line my lights will go up in smoke as I have no regulation just rectification. But they have been working for 1/2 a year 24/7 at a mill I did not expect them to last as I have up to 1200 hp motor and many +100 hp motors starting and stopping throughout the day.

So if your new driver has the correct voltage the amperage can be higher but peak life is achieved with the correct voltage and constant current.

  • Thanks for your answer. I have found drivers on Amazon that specify the same voltage and amperage. It's the dimming capability I was unsure about. – Tim Feb 2 '20 at 18:09
  • If the driver can dim LED’s will also it’s usually the driver that is limited. – Ed Beal Feb 3 '20 at 2:30
  • Sorry, I don't follow this comment. Could you clarify please? – Tim Feb 3 '20 at 9:31
  • Your comment was around dimming, the dimming is not a function of the LED but a function of the driver, so if the driver Is dim able the LED’s should dim. – Ed Beal Feb 3 '20 at 14:20

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