EEVblog 1617 - Architectural LED Lighting Build + Test

Nice! When you mentioned you were going down this route I was thinking you were just getting pre-made fixtures installed by someone, nice that you can just buy the extrusion and LED strips separately from local stores to get exactly what your application needs and DIY it. Nicely suited for future repair and/or upgrades. Strange that the 32.6 W tape came out lower than claimed. Even if you use the 83 mm segment length from the datasheet (12 segments per meter), it still only comes out to ~29.5 W (~10% below spec). For it to meet the 32.6 W spec it would have to be driven at 113 mA. The INK1101 datasheet says the max drive current is 120 mA for 24 V applications with 7 LEDs in series which this appears to be (and 120 mA is typical max current for those 2538 LEDs), that would give 34.6 W, so the circuit could do it. Product picture in the datasheet also appears to have the same 6.2 ohm sense resistor, so it's not like they just sent you the wrong item, no idea where they got 32.6 W from.

I've done several of the DIY aluminum extrusion + LED tape lights. i've been using the high power density COB tape on my latest builds and skip the diffuser. To address voltage drop dimming at the far end of the tape, particularly on the really long ones , especially if 12V rather than 24V, I've taken to connecting the negative lead to the extrusion, then at the far end connecting the extrusion to the negative tape bus. This splits the tape feed to opposite ends so the voltage drop is the same anywhere along the tape and light output constant.

Dave! I think why you get 28 W/m out of the strip. You measured 80 mm and 2,4 W of power consumption. That gives you 2,4 W / 0,08 m = 30 W/m But if you measure the length not between the cutting lines, but between the lines with a pattern you get: 75 mm length (approximately) and 2,4 W. Then 2,4 W / 0,075 m = 32 W/m. The manufacturer was a little tricky there haha.

In 1993 my father was in the hospital for a few days, and these LED fixtures you have remind me very much of the lights mounted above the patients' beds in the ward Dad was in. They were also fitted with lights that pointed up to the ceiling to provide room lighting, and then a light that pointed down towards the patent's bed. Of course those lights used fluorescent tubes, not LEDs.

Light technician here: I hate wall washer lights. For a dinner room, you need 100lux to confirtably see other people faces and what you are eating. Most indoor LED lights today have an efficiency of 60 lumens per watt, which for the living room translates to ~1.7 watt per square meter. That's a blessing in terms of energy consumption. But they are to be installed perpendicular to the surface you want to illuminate. When lighting is indirect, the efficiency drops by ~5 lumens per watt, or less, which translates to ~20 watts per square meter for an illuminance of 100 lux.

Project time again! I missed this. That's an interesting profile and LED strip.

Back in the late '90s I was asked to pull a part number for RAM chip of some type, and the designer gave me a preliminary datasheet that was dated about a month earlier. When I went to the mfr's website to get the current spec, it was flagged as LTB! I called to verify- yes, it was being replaced by a denser part with a slightly different pinout. The designer was not happy! That was the shortest product lifespan I ever came across, besides "vapor" parts.

5.7W approx per meter just to heat the resistors? I've used 12v strips before with the resistors, and the efficiency is questionable. Due to the heat, you have to ensure they are stuck to a metal surface. If you try sticking them to plastic, they can soften the adhesive and fall off and the LED's overheat. A mistake I made when first using strips. For the 12v variety a big mistake is assuming they will be ok for a vehicle (boat) where the 12v can go up to 14.4v - they don't last very long if you do that.

Aren’t these dimmers actually dimming by PWM? That would be typical for constant voltage LED drivers.

Over spec-ing your Power Supply is also better for Efficiency. (well, less heat longer life I guess) 😄

Coincidence! I'm DIY'ing a LED driver dim signal controller, these 0-10V / 1-10V dimmer inputs seem to be an industry standard. Many thanks to the forum, they helped me come up with a dual OpAmp circuit to convert 3.3V PWM to 0-10V smooth DC. I had problems with the uC output not going full zero (0.3V when low), that was fed into an RC filter and amplified by a single OpAmp so my low output was 1V. Luckily, I had ordered a dual rail-to-rail OpAmp, now I'm using the first one to convert 3.3V to 12V PWM as input for the RC, the 2nd one is used as a buffer, that goes near to absolute 0 (unloaded) output. Now I'm hung up on implementing schedules on the ESP32-C3 micro. Never programmed anything serious in C, this would be so much easier in any memory-safe language... I can already control the duty cycle via HTTPS and I'm thinking about just leaving the software as-is and implement scheduling on an always-on client. Ultimately, I want to spin a PCB that can plug onto the ESP DevKit boards (dirty cheap), 12V in, 0-12V out.

With LED lighting I go for high CRI like CRI>95 and take care that also R9 and R12 are given and have reasonable values. I accept CRI80 like I saw in your datasheet for storage rooms, cellar or staircase. The difference is easily visible especially when you light objects with saturated colours.

Hopefully the replacement for the 1101 lasts longer than the 1101s in my swimming pool lights!

"Right up the clacker" you craic me up with your Ausie vernacular Dave

I think it would be relatively easy to make a pick and place machine for arbitrary length LED strip, you'd just need some tooling holes in the strip, and a couple cog wheels to advance it. Might even be able to make it in a continuous process, rather than being fed from wheels.

Among the first humans. Wohooo!

can you take a dive into the efficiency differences of both types? comparing the lumen per watt. it would seem that the ones with the driver is much more efficient.

Nice test but I missed measuring the lumens. Perhaps the blue tape led strips emit the promised lumens at a lower power as specified and perform even better than the 3M type.

That Aluminium housing seems to be a bit oversized, for the LED strips running at 32W or so, especially since the constant driver is built in a separate assembly. For interrest sake, did you calculate of did they provide the Lifespan of these LEDs running at 19W, 32W 12hours/day? I assume the LEDs lifespan will dictate the warranty of the light.

Why would a led strip with active drivers be able to handle morre current than a led strip with drop resistors?