130 Watt Cree-Based 98-CRI Led Lamp for Artist’s Studio — Solving the Inrush Current Problem

I’d assumed that my previous LED lamp project was it for a while, but I needed an artist studio lamp with very strong light and the highest color rendition index available. So, when I stumbled on these new Cree Chip-on-Board LED units, I went “wow” and went for it. These LED units have a CRI rating of 98 — meaning that 98 percent of the visible spectrum is illuminated, making these LEDs suitable for the most demanding photographers or oil painters or other artists.

With their rating of 36 volts nominal, four in series is perfect for a nominal 144V. In assembling the unit, the individual LEDs were mounted first on a small extruded heatsink. Thanks to their ceramic board mounting the LEDs had no electrical connection to the heatsink. The heatsink was then screwed into a 12 inch stainless kitchen pan, resulting in four units like this (apologies for the poor photo — it’s shown mounted to the ceiling):

In building the control box, a very high value to the filter capacitor was desired, for best performance, so two 470 uF in parallel capacitors were used. After building the circuit, this change resulted in repeated damage to the AC switch due to excessive turn-on current, during the time that the capacitors were charging. This is referred to as “inrush current”. And the problem did not go away by leaving the switch on and just plugging the unit in already on — there was quite a large arc and pop at the wall socket. Too scary!

The solution was a new change in the driver circuit, to cause the initial charge of the filter circuit to proceed so slowly that no large current inrush occurs.

In the new design, transistor Q2 goes slowly from an off state to an on state after power is applied, causing the charge entering C1 and C5 to be 5 amps or less, preserving the switch SW1A from blowing out. Note the resistor R14. This resistor is required to avoid blowout of the Q2 mosfet – the RC time constant of the 2.2M resistor and the input capacitance of Q2 results in a delay which prevents damage to the gate. Learning this cost me 8 MosFETs! Below is shown the PCB just before final assembly.

The increased power requires installation of a fan. In this case, the power FET was mounted to the heatsink, mounted directly to the fan, which is set to expel air. Intake holes were drilled a few inches away from the fan.

Operation of the light is wonderful for an artist’s studio. The natural light from this high power LED lamp reaches an intensity which feels very close to midday sun, and colors pop with a richness that is perfect for photography.

I’ll close with the LTSpice listing, in case the reader is interested in playing with the circuit operation.

Version 4
SHEET 1 7116 1492
WIRE 912 -208 224 -208
WIRE 1008 -208 912 -208
WIRE 1376 -208 1008 -208
WIRE 2304 -208 1376 -208
WIRE 2544 -208 2304 -208
WIRE 2544 -144 2544 -208
WIRE 2304 -112 2304 -208
WIRE 2544 -32 2544 -80
WIRE 224 64 224 -208
WIRE 1280 96 848 96
WIRE 1728 96 1280 96
WIRE 1856 96 1728 96
WIRE 2128 96 1856 96
WIRE 2304 96 2304 -32
WIRE 2304 96 2128 96
WIRE 2544 96 2544 32
WIRE 1600 176 1472 176
WIRE 1968 176 1600 176
WIRE 1472 240 1472 176
WIRE 1968 240 1968 176
WIRE 2128 240 2128 96
WIRE 1008 272 1008 -208
WIRE 1968 384 1968 320
WIRE 2544 416 2544 176
WIRE 1376 448 1376 -208
WIRE 1008 464 1008 352
WIRE 1344 464 1008 464
WIRE 2304 464 2304 96
WIRE 1472 480 1472 320
WIRE 1472 480 1408 480
WIRE 2128 480 2128 320
WIRE 2272 480 2128 480
WIRE 1280 496 1280 96
WIRE 1344 496 1280 496
WIRE 2496 496 2336 496
WIRE 1968 512 1968 464
WIRE 2272 512 1968 512
WIRE 1600 544 1600 176
WIRE 1728 544 1728 96
WIRE 1968 544 1968 512
WIRE 2128 624 2128 480
WIRE 2544 624 2544 512
WIRE 2544 624 2128 624
WIRE 1008 640 1008 464
WIRE 1120 640 1008 640
WIRE 1856 672 1856 96
WIRE 2544 672 2544 624
WIRE 1120 688 1120 640
WIRE 912 704 912 -208
WIRE 1008 704 1008 640
WIRE 912 816 912 768
WIRE 1008 816 1008 768
WIRE 1008 816 912 816
WIRE 1120 816 1120 768
WIRE 1120 816 1008 816
WIRE 1200 816 1120 816
WIRE 1376 816 1376 512
WIRE 1376 816 1200 816
WIRE 1600 816 1600 608
WIRE 1600 816 1376 816
WIRE 1728 816 1728 608
WIRE 1728 816 1600 816
WIRE 1856 816 1856 736
WIRE 1856 816 1728 816
WIRE 1968 816 1968 624
WIRE 1968 816 1856 816
WIRE 2304 816 2304 528
WIRE 2304 816 1968 816
WIRE 2544 816 2544 752
WIRE 2544 816 2304 816
WIRE 848 912 848 96
WIRE 848 912 576 912
WIRE 576 976 576 912
WIRE 848 1056 848 912
WIRE 848 1184 848 1136
WIRE 1008 1184 848 1184
WIRE 1136 1184 1008 1184
WIRE 576 1216 576 1040
WIRE 848 1216 848 1184
WIRE 848 1216 576 1216
WIRE 1200 1232 1200 816
WIRE 848 1264 848 1216
WIRE 1008 1312 1008 1184
WIRE 1136 1312 1136 1184
WIRE 1152 1312 1136 1312
WIRE 224 1392 224 144
WIRE 848 1392 848 1328
WIRE 848 1392 224 1392
WIRE 1008 1392 1008 1376
WIRE 1008 1392 848 1392
WIRE 1200 1392 1200 1328
WIRE 1200 1392 1008 1392
WIRE 1568 1392 1200 1392
WIRE 1664 1392 1568 1392
WIRE 1568 1472 1568 1392
FLAG 1568 1472 0
DATAFLAG 1472 816 “”
DATAFLAG 1200 1120 “”
DATAFLAG 960 1184 “”
DATAFLAG 1152 1392 “”
SYMBOL voltage 224 48 R0
WINDOW 123 24 124 Left 2
WINDOW 39 -5 -286 Left 2
WINDOW 3 -7 -321 Left 2
SYMATTR SpiceLine Rser=.03
SYMATTR Value PULSE(0 155 .1 .016 .016 1 2 158)
SYMATTR InstName V1
SYMBOL res 1104 672 R0
SYMATTR InstName R9
SYMATTR Value 121000
SYMBOL cap 992 704 R0
SYMATTR InstName C1
SYMATTR Value 1e-6
SYMBOL nmos 2496 416 R0
SYMATTR InstName M1
SYMATTR Value IXFX90N30
SYMBOL res 2528 656 R0
SYMATTR InstName R6
SYMATTR Value 5.6
SYMBOL res 2288 -128 R0
SYMATTR InstName R7
SYMATTR Value 49900
SYMBOL cap 1712 544 R0
SYMATTR InstName C2
SYMATTR Value 10e-6
SYMBOL res 1952 528 R0
SYMATTR InstName R10
SYMATTR Value 9999
SYMBOL res 1952 368 R0
SYMATTR InstName R11
SYMATTR Value 1
SYMBOL zener 1872 736 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D151
SYMATTR Value TDZ6_2B
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 896 704 R0
SYMATTR InstName C3
SYMATTR Value 940e-6
SYMBOL OpAmps\UniversalOpamp2 2304 496 R0
SYMATTR InstName U1
SYMBOL res 1952 224 R0
SYMATTR InstName R1
SYMATTR Value 10000
SYMBOL res 2112 224 R0
SYMATTR InstName R2
SYMATTR Value 5600
SYMBOL res 992 256 R0
SYMATTR InstName R3
SYMATTR Value 3e6
SYMBOL OpAmps\UniversalOpamp2 1376 480 R0
SYMATTR InstName U2
SYMBOL cap 1584 544 R0
SYMATTR InstName C4
SYMATTR Value 10e-6
SYMBOL res 1456 224 R0
SYMATTR InstName R4
SYMATTR Value 49.9
SYMBOL zener 2560 -80 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D152
SYMATTR Value UMZ24K
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL zener 2560 32 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D153
SYMATTR Value UMZ27K
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 2528 80 R0
SYMATTR InstName R5
SYMATTR Value 215
SYMBOL nmos 1152 1232 R0
SYMATTR InstName M2
SYMATTR Value IXFX90N30
SYMBOL cap 992 1312 R0
SYMATTR InstName C5
SYMATTR Value 10e-6
SYMBOL zener 864 1328 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value TDZ18B
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 832 1040 R0
SYMATTR InstName R12
SYMATTR Value 1e6
SYMBOL diode 592 1040 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D3
SYMATTR Value MURS320
TEXT 728 -328 Left 2 !.tran 0 5 0 .01 startup
TEXT 2616 720 Left 2 ;2 watts
TEXT 2336 88 Left 2 ;1/4 W
TEXT 2256 112 Left 2 ;1/8 W
TEXT 1984 368 Left 2 ;10K pot
TEXT 2024 464 Left 2 ;Grn
TEXT 1912 368 Left 2 ;Blu
TEXT 2552 376 Left 2 ;Blk
TEXT 2312 -256 Left 2 ;Red
TEXT 744 -360 Left 2 !.include opamp.sub
TEXT 2592 -8 Left 2 ;Modeling the\nLED array with\nZener diodes

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130 Watt LED Lamp with 255 CRI-95 LEDs

About 90 percent of the time, when I buy a light or flashlight, my feeling is “It’s not bright enough”. The rest of the time, I may feel it is “bright enough, barely.” Here is a light that is TOO BRIGHT. Which means it is guaranteed to be bright enough no matter what its use will be. And it has the feature of continuously variable brightness, from near zero to blindingly bright.

To upgrade the lamp design, the number of LEDs per panel was raised from 30 to 51, giving 255 LEDs total, and to upgrade the color balance, the new 95-CRI LEDs from LumiLED were used. These LEDs are much less efficient than the 90-CRI LEDs, since they are more optimized for bandwidth. The array of 255 LED’s gives about 130 Watts, which is a fair amount of power for a solid state lamp this size without a fan. The lamp is built and it works, but I worry that it might overheat too easily. On the other hand, the light output is so high, that most of the time this lamp is TOO bright at maximum setting and I have to dial it down. Walking into a room with this light at maximum is like walking outside into the noonday sun. The continuously variable brightness with the pot control is a real pleasure to use. The photo below is taken near minimum brightness, so that the individual LEDs are visible. Minimum brightness is a faint glow, too dim even for a nightlight, yet the maximum brightness is impossible to look at directly, like looking at the sun. The usable dynamic range of this lamp from minimum to maximum brightness is astounding. I’m quite pleased with it, and I’m going to enjoy oil painting under its “Noonday Sun” illumination. Total cost out of pocket for copper-clad PCBs, LED’s, potentiometer, heat sink, plastic box, and Ace Hardware Work Lamp, was about $95, with me using other miscellaneous parts from my junk boxes. Yet this lamp far outperforms anything you can buy commercially for less than $400. It must be one of the highest performance accurately natural sunlight lamps you can own.

Construction is similar to the previous lamp. There are differences in the uprated control box, to allow for the 130 watt operation. The main filter capacitor is increased to at least 680 uF because of the higher current drain, and the zener diode is increased to 8.2 V, with increased dropping current (R2) to allow for more volts on the gate of the MosFET. Another new feature is that I applied a conformal coating to the LED panels, since they have high voltage present and would be quite hazardous if someone stuck their hand into the lamp while it was on.

The simulation is similar to the previous controller, so I’ll omit it.

Should I make this into a product, or a kit? Would you pay $500 for a complete kit, with the 5 pc boards (fully tinned and laid out for assembly), the LEDs, box, other components? Or $600 for the 5 PCB’s with LEDs already mounted? Soldering the LEDs yourself is only recommended if you are a highly skilled electronics assembler and have experience with temperature sensitive surface mount components.

That’s it for these LED light projects for a while, I think. I’ll move on to other challenges. I thought of a way to make my ESOLA project more interesting and challenging to design, and can’t wait to start. Write to me if you have comments!

Manufacturable 50-80W LED String DC Control Circuit

In my previous LED Lamp post, I pointed out that the control circuit was a “hobbyist” quality, because it tended to require adjusting resistor values. I promised to develop a more manufacturable and reproducible circuit, and here it is. The additional complexity required using an Op Amp.

The key difference is that instead of producing a voltage to apply to the MosFET gate, and relying on the FET to drive the array proportionally, a closed loop control circuit forces the circuit to deliver the desired current by driving the MosFET exactly as much as needed. In this way, variations in the MosFET gain are no longer relevant, resistors don’t have to be adjusted, and each circuit behaves the same.

The second of the two op amps serves to detect when the rectified DC voltage goes above about 158V, shutting down the light to prevent overheating of the MosFET. Here is the LTSpice simulation schematic. To reduce complexity, I modeled the 150 LED’s with Zener Diodes D152, D153, and R5.

The simulation shows that total drive current Id(M1) stays stable above an input voltage of 153V [V(n001)] and shuts down above 160V, preventing device power dissipation from going above 4W.

Schematic, as tested:

This is the LTSpice listing. To open in LTSpice.Exe, save the following text as a file “LEDLIGHT23.ASC”.

Version 4
SHEET 1 7116 1040
WIRE 912 -208 736 -208
WIRE 1008 -208 912 -208
WIRE 1376 -208 1008 -208
WIRE 2304 -208 1376 -208
WIRE 2544 -208 2304 -208
WIRE 2544 -144 2544 -208
WIRE 2304 -112 2304 -208
WIRE 2544 -32 2544 -80
WIRE 736 64 736 -208
WIRE 1728 96 1280 96
WIRE 1856 96 1728 96
WIRE 2128 96 1856 96
WIRE 2304 96 2304 -32
WIRE 2304 96 2128 96
WIRE 2544 96 2544 32
WIRE 1600 176 1472 176
WIRE 1968 176 1600 176
WIRE 1472 240 1472 176
WIRE 1968 240 1968 176
WIRE 2128 240 2128 96
WIRE 1008 272 1008 -208
WIRE 1968 384 1968 320
WIRE 2544 416 2544 176
WIRE 1376 448 1376 -208
WIRE 1008 464 1008 352
WIRE 1344 464 1008 464
WIRE 2304 464 2304 96
WIRE 1472 480 1472 320
WIRE 1472 480 1408 480
WIRE 2128 480 2128 320
WIRE 2272 480 2128 480
WIRE 1280 496 1280 96
WIRE 1344 496 1280 496
WIRE 2496 496 2336 496
WIRE 1968 512 1968 464
WIRE 2272 512 1968 512
WIRE 1600 544 1600 176
WIRE 1728 544 1728 96
WIRE 1968 544 1968 512
WIRE 2128 624 2128 480
WIRE 2544 624 2544 512
WIRE 2544 624 2128 624
WIRE 1008 640 1008 464
WIRE 1120 640 1008 640
WIRE 1856 672 1856 96
WIRE 2544 672 2544 624
WIRE 1120 688 1120 640
WIRE 912 704 912 -208
WIRE 1008 704 1008 640
WIRE 736 816 736 144
WIRE 912 816 912 768
WIRE 912 816 736 816
WIRE 1008 816 1008 768
WIRE 1008 816 912 816
WIRE 1120 816 1120 768
WIRE 1120 816 1008 816
WIRE 1376 816 1376 512
WIRE 1376 816 1120 816
WIRE 1600 816 1600 608
WIRE 1600 816 1376 816
WIRE 1728 816 1728 608
WIRE 1728 816 1600 816
WIRE 1856 816 1856 736
WIRE 1856 816 1728 816
WIRE 1968 816 1968 624
WIRE 1968 816 1856 816
WIRE 2304 816 2304 528
WIRE 2304 816 1968 816
WIRE 2544 816 2544 752
WIRE 2544 816 2304 816
WIRE 736 848 736 816
FLAG 736 848 0
SYMBOL voltage 736 48 R0
WINDOW 123 24 124 Left 2
WINDOW 39 -5 -286 Left 2
WINDOW 3 -7 -321 Left 2
SYMATTR SpiceLine Rser=.03
SYMATTR Value PWL(0 100 1 153 1.1 153 2 158 2.1 158 3 200)
SYMATTR InstName V1
SYMBOL res 1104 672 R0
SYMATTR InstName R9
SYMATTR Value 121000
SYMBOL cap 992 704 R0
SYMATTR InstName C1
SYMATTR Value 1e-6
SYMBOL nmos 2496 416 R0
SYMATTR InstName M1
SYMATTR Value IXFX90N30
SYMBOL res 2528 656 R0
SYMATTR InstName R6
SYMATTR Value 5.6
SYMBOL res 2288 -128 R0
SYMATTR InstName R7
SYMATTR Value 49900
SYMBOL cap 1712 544 R0
SYMATTR InstName C2
SYMATTR Value 10e-6
SYMBOL res 1952 528 R0
SYMATTR InstName R10
SYMATTR Value 9999
SYMBOL res 1952 368 R0
SYMATTR InstName R11
SYMATTR Value 1
SYMBOL zener 1872 736 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D151
SYMATTR Value TDZ6_2B
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 896 704 R0
SYMATTR InstName C3
SYMATTR Value 120e-6
SYMBOL OpAmps\UniversalOpamp2 2304 496 R0
SYMATTR InstName U1
SYMBOL res 1952 224 R0
SYMATTR InstName R1
SYMATTR Value 10000
SYMBOL res 2112 224 R0
SYMATTR InstName R2
SYMATTR Value 5600
SYMBOL res 992 256 R0
SYMATTR InstName R3
SYMATTR Value 3e6
SYMBOL OpAmps\UniversalOpamp2 1376 480 R0
SYMATTR InstName U2
SYMBOL cap 1584 544 R0
SYMATTR InstName C4
SYMATTR Value 10e-6
SYMBOL res 1456 224 R0
SYMATTR InstName R4
SYMATTR Value 49.9
SYMBOL zener 2560 -80 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D152
SYMATTR Value UMZ24K
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL zener 2560 32 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D153
SYMATTR Value UMZ27K
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 2528 80 R0
SYMATTR InstName R5
SYMATTR Value 215
TEXT 728 -328 Left 2 !.tran 0 3 0 .01 startup
TEXT 2616 720 Left 2 ;2 watts
TEXT 2336 88 Left 2 ;1/4 W
TEXT 2256 112 Left 2 ;1/8 W
TEXT 1984 368 Left 2 ;10K pot
TEXT 2024 464 Left 2 ;Grn
TEXT 1912 368 Left 2 ;Blu
TEXT 2552 376 Left 2 ;Blk
TEXT 2312 -256 Left 2 ;Red
TEXT 744 -360 Left 2 !.include opamp.sub
TEXT 2592 -8 Left 2 ;Modeling the\nLED array with\nZener diodes

50 Watt LED Lamp for Accurate Color Reproduction

I’m an oil painter, and for a long time I’ve been unable to work at home because our interior lighting is both too dim, and too “warm”. Colors that are seen under unnatural lighting don’t look right. Painting under the wrong light is — in a sense — painting blind to some colors. In the past, broadband lighting required hot, inefficient incandescent floodlights, because LED’s did not produce an even spectrum of light. But advances have been made. LED lighting is characterized by a “CRI” number – color rendition index, in which perfect color reproduction rates 100. There have been high accuracy LED’s with a 90 CRI rating for a while, but recently high power LEDs with a 95 rating have become available. Some manufacturers have been offering these 95 CRI light bulbs for artists at an expensive price, but I decided to save money by buying the LED’s from an industrial supply house and building my own. This way I could make a single dimmable unit with very high power, optimum color purity, and not have to use awkward “bulbs”. The 95-CRI LED’s cost about four times as much as the 90-CRI LED’s – this gives manufacturers a terrible temptation to cheat and use fewer of the 95-CRI parts than they should, just to save money, so the do-it-yourself route for me is the way to go. I think it is very likely that some of the expensive LED lights for sale by unscrupulous sellers are not as advertised, just because the consumer cannot do spectral measurements to verify what they are buying.

I chose these L128-5095HA35000B1 parts, and bought 200. Like the LED’s in my previous project, these have a nominal 3 volt rating, so a string of 50 gives the right voltage for a 158V full wave rectified 112 VAC. Three such strings in parallel, each string about 15W, gives almost 50W total, and that should give about as much light as a 250W incandescent floodlight. I picked up a cheap clamp-on heat lamp fixture from Ace Hardware ($17) and a plastic project box, and was ready to go.

My previous design had no protection against overvoltage causing overheating and burnout, so back to the LTSpice simulation to improve it. This time, I went with a simple Zener diode to supply a 6.2V reference, and added a transistor to shut down the power FET if the input voltage got too high, and thermally bound it to the main FET so that it would also act to some extent as a thermal shutdown device. Here is the LTSpice drawing. Remember these are modeled devices, not actual devices. The original LTSpice drawing file appears at the end of this article. Yes, there are 150 LED’s! Click on it to enlarge.

Here are the simulation results. The green trace shows current through the LED’s, and the parts values are chosen to allow about 450 milliamps (Id(M1) when the rectified AC results in DC voltages (V(n001)) in the range of about 153 to 158. The red trace shows total device power dissipation in the MosFET, demonstrating that the shutoff circuit prevents it from getting too hot when the DC voltage goes very high. The shutoff circuit also should begin limiting current when it gets hot, because the Q1 junction acts as a temperature sensor, dropping in forward voltage by over 2 mv per C degrees.

Designing the circuit this way is easy, since changing a few parts values gives quick answers. But the fundamental problem with this kind of circuit is that the parts values (such as in the potentiometer chain) depend on the turn-on voltage of the MosFET, which varies a lot from device to device. Building this kind of circuit is fast and simple, but resistor selection is needed to give optimum operation. Two resistors need to be selected in the schematic. (See my final circuit for a more reproducible design.)

Adjust the value of R3 so that the average voltage across each LED is about 2.76V when the pot is at maximum, to prevent overdriving of the LED’s. Adjust R5 so that shutoff does not occur until just a little higher than nominal 115VAC mains voltage. Under some conditions, R6 might need adjustment too so that the 10K pot goes low enough to turn off the LED array. Clearly, these adjustments might be OK for a hobbyist, but for a high volume product this would never fly. Additional complexity would be needed.

I decided to mount the LED’s on 5 pcb’s, arranged in a pentagonal design. So, with 150 LED’s total, each pane would have 30 LED’s, which would be 10 LED’s in each of the 3 parallel strings. It was fun figuring out how to arrange them best, and cutting the pattern in the PCB using a Dremel tool and a thin diamond wheel. Soldering the LED’s in place took some practice — I damaged 10 or so in the first 30. The key seems to be in preparing the surface for the LED beforehand with a little solder, then placing the LED exactly at the right spot, then heating the surface near the IC so that the heat flows to the part and does the soldering without having to manipulate the part manually. Also note that the copper layer is tinned — I had to do this by hand. This was for two reasons (1) improved ability to solder the LED’s, (2) the copper color would have contaminated the color spectrum of the reflected light. (Technique: first apply some liquid Zinc Chloride flux to the surface, then wipe a hot solder wetted copper braid over the surface using a 700+ degree soldering iron.)

The five panels were then assembled into the full array:

The dimmer and drive circuitry were assembled into a small plastic box. I attached the power FET to a heatsink, just in case cooling would be needed, but it turned out that no air circulation holes were needed.

Here’s the finished LED lamp. It is VERY bright, and the purity of the light is excellent! It’s a pleasure being able to turn up and down the brightness using the control box. This photo was taken at low power, and it’s still so bright that artifacts are all over the image. I set it up so that it illuminates my work bench where I will be oil painting, and I’m very happy with the brightness of the colors. It feels like the noonday sun is shining through a window.

LTSpice listing. Copy the text below and save as “Ledlight21.asc” and then open the file in LTSpice.exe.

Version 4
SHEET 1 7116 980
WIRE 3808 -560 2208 -560
WIRE 5344 -560 3808 -560
WIRE 6912 -560 5344 -560
WIRE 2768 -512 2544 -512
WIRE 3072 -512 2848 -512
WIRE 3392 -512 3168 -512
WIRE 3712 -512 3488 -512
WIRE 3808 -512 3808 -560
WIRE 4304 -512 4080 -512
WIRE 4608 -512 4384 -512
WIRE 4928 -512 4704 -512
WIRE 5248 -512 5024 -512
WIRE 5344 -512 5344 -560
WIRE 5872 -512 5648 -512
WIRE 6176 -512 5952 -512
WIRE 6496 -512 6272 -512
WIRE 6816 -512 6592 -512
WIRE 6912 -512 6912 -560
WIRE 1392 -128 1216 -128
WIRE 1600 -128 1392 -128
WIRE 2208 -128 2208 -560
WIRE 2208 -128 1600 -128
WIRE 2208 -96 2208 -128
WIRE 1600 -64 1600 -128
WIRE 2096 16 1904 16
WIRE 2208 16 2208 -16
WIRE 2208 16 2096 16
WIRE 1216 64 1216 -128
WIRE 2208 64 2208 16
WIRE 2768 128 2768 -512
WIRE 2848 128 2768 128
WIRE 3072 128 3072 -512
WIRE 3168 128 3072 128
WIRE 3392 128 3392 -512
WIRE 3488 128 3392 128
WIRE 3712 128 3712 -512
WIRE 3808 128 3712 128
WIRE 4304 128 4304 -512
WIRE 4384 128 4304 128
WIRE 4608 128 4608 -512
WIRE 4704 128 4608 128
WIRE 4928 128 4928 -512
WIRE 5024 128 4928 128
WIRE 5248 128 5248 -512
WIRE 5344 128 5248 128
WIRE 5872 128 5872 -512
WIRE 5952 128 5872 128
WIRE 6176 128 6176 -512
WIRE 6272 128 6176 128
WIRE 6496 128 6496 -512
WIRE 6592 128 6496 128
WIRE 6816 128 6816 -512
WIRE 6912 128 6816 128
WIRE 2544 176 2544 128
WIRE 4080 176 4080 128
WIRE 4080 176 2544 176
WIRE 5648 176 5648 128
WIRE 5648 176 4080 176
WIRE 2208 240 2208 144
WIRE 2544 256 2544 176
WIRE 2208 336 2208 320
WIRE 2352 336 2208 336
WIRE 2496 336 2352 336
WIRE 2208 352 2208 336
WIRE 2352 512 2352 336
WIRE 2352 512 1776 512
WIRE 1776 592 1776 512
WIRE 1600 640 1600 16
WIRE 1600 640 1488 640
WIRE 1712 640 1600 640
WIRE 1904 672 1904 16
WIRE 2096 672 2096 16
WIRE 2544 672 2544 352
WIRE 1600 688 1600 640
WIRE 2208 688 2208 432
WIRE 1392 704 1392 -128
WIRE 1488 704 1488 640
WIRE 1216 816 1216 144
WIRE 1392 816 1392 768
WIRE 1392 816 1216 816
WIRE 1488 816 1488 768
WIRE 1488 816 1392 816
WIRE 1600 816 1600 768
WIRE 1600 816 1488 816
WIRE 1776 816 1776 688
WIRE 1776 816 1600 816
WIRE 1904 816 1904 736
WIRE 1904 816 1776 816
WIRE 2096 816 2096 736
WIRE 2096 816 1904 816
WIRE 2208 816 2208 768
WIRE 2208 816 2096 816
WIRE 2544 816 2544 752
WIRE 2544 816 2208 816
WIRE 1216 848 1216 816
FLAG 1216 848 0
SYMBOL voltage 1216 48 R0
WINDOW 123 24 124 Left 2
WINDOW 39 -54 916 Left 2
WINDOW 3 -144 885 Left 2
SYMATTR SpiceLine Rser=.03
SYMATTR InstName V1
SYMATTR Value PWL(0 100 1 153 1.1 153 2 158 2.1 158 3 200)
SYMBOL res 1584 672 R0
SYMATTR InstName R9
SYMATTR Value 1000
SYMBOL res 1584 -80 R0
SYMATTR InstName R5
SYMATTR Value 300000
SYMBOL cap 1472 704 R0
SYMATTR InstName C1
SYMATTR Value 1e-6
SYMBOL nmos 2496 256 R0
SYMATTR InstName M1
SYMATTR Value IXFX90N30
SYMBOL res 2528 656 R0
SYMATTR InstName R6
SYMATTR Value 5
SYMBOL LED 2528 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D1
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2528 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D2
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2528 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D3
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2528 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D4
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2528 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D5
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2528 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D6
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2528 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D7
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2528 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D8
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2528 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D9
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2528 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D10
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D11
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D12
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D13
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D14
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D15
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D16
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D17
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D18
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D19
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 2832 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D20
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D21
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D22
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D23
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D24
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D25
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D26
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D27
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D28
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D29
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3152 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D30
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D31
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D32
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D33
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D34
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D35
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D36
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D37
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D38
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D39
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3472 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D40
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D42
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D43
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D44
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D45
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D46
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D47
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D48
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D49
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D50
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 3792 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D51
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 2192 -112 R0
SYMATTR InstName R7
SYMATTR Value 100000
SYMBOL cap 1888 672 R0
SYMATTR InstName C2
SYMATTR Value 10e-6
SYMBOL res 2192 672 R0
SYMATTR InstName R2
SYMATTR Value 12000
SYMBOL res 2192 336 R0
SYMATTR InstName R10
SYMATTR Value 9999
SYMBOL res 2192 224 R0
SYMATTR InstName R11
SYMATTR Value 1
SYMBOL npn 1712 592 R0
SYMATTR InstName Q1
SYMATTR Value 2N2222
SYMBOL LED 4064 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D41
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4064 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D52
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4064 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D53
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4064 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D54
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4064 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D55
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4064 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D56
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4064 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D57
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4064 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D58
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4064 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D59
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4064 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D60
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D61
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D62
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D63
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D64
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D65
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D66
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D67
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D68
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D69
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4368 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D70
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D71
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D72
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D73
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D74
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D75
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D76
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D77
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D78
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D79
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 4688 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D80
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D81
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D82
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D83
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D84
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D85
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D86
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D87
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D88
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D89
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5008 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D90
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D91
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D92
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D93
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D94
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D95
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D96
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D97
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D98
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D99
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5328 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D100
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D101
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D102
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D103
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D104
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D105
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D106
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D107
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D108
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D109
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5632 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D110
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D111
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D112
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D113
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D114
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D115
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D116
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D117
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D118
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D119
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 5936 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D120
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D121
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D122
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D123
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D124
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D125
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D126
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D127
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D128
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D129
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6256 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D130
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D131
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D132
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D133
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D134
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D135
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D136
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D137
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D138
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D139
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6576 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D140
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 -512 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D141
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 -448 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D142
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 -384 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D143
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 -320 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D144
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 -256 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D145
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 -192 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D146
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 -128 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D147
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 -64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D148
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 0 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D149
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL LED 6896 64 R0
WINDOW 0 -49 30 Left 2
WINDOW 3 80 31 Left 2
SYMATTR InstName D150
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL zener 2112 736 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D151
SYMATTR Value TDZ6_2B
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1376 704 R0
SYMATTR InstName C3
SYMATTR Value 120e-6
SYMBOL res 2192 48 R0
SYMATTR InstName R1
SYMATTR Value 2740
TEXT 1256 896 Left 2 !.tran 0 3 0 .01 startup
TEXT 2616 720 Left 2 ;2 watts
TEXT 2240 8 Left 2 ;1/4 W
TEXT 1632 32 Left 2 ;1/8 W
TEXT 2216 216 Left 2 ;10K pot
TEXT 2264 320 Left 2 ;Grn
TEXT 2224 464 Left 2 ;Yel
TEXT 2160 216 Left 2 ;Blu
TEXT 2552 216 Left 2 ;Blk
TEXT 2216 -256 Left 2 ;Red

Make Your Own Dimmable White LED Lighting Strip

[My most recent LED light project is here.] My new Kawai ES-920 digital piano set came with its own nice console stand, which I modified by designing and building a fold-down wooden lid. When folded down, the piano becomes a nice desk, with a rugged wooden surface protecting the piano underneath.

But there was a problem. With the desk top folded up, it blocked a lot of light, and since the inside of the desktop was now a music holder, it needed some kind of lighting. I thought of a LED strip of course, and there is a commercial LED strip which is 48 inches long (the piano is about 53.5 inches long overall) but it turned out that it was simply too “fat” to fit on the underside of the desktop. I needed something very low profile. So I thought, “wouldn’t it be fun to make my own LED strip?” Fun, yes, but I really didn’t know what I’d talked myself into.

The first task was choosing the LED’s. I choose this one, and was surprised at how inexpensive it is:

So, now some basic arithmetic. I wanted to use simple rectified US mains power for the drive. 110VAC. With a full wave rectifier, that means it would be two diode drops lower than the RMS peak, so squareroot(2)*110 – 1.2 equals about 154.5 VDC. These LEDs are rated at 3 VDC each. So the minimum number of LEDs I must use at 154.5 VDC equals 154.5/3 = 51. The piano is 53 inches wide, so if I place the LEDs about one inch apart, 51 LEDs will give 51 inches, which is perfect. I could build it with more LEDs, up to a limit, but not with less. Unless there is a series control element.

It definitely needs a switch, I thought. But what if it ends up being too bright? So, now I realized I wanted a series control element and switch both. Since this is a DC circuit, all the control can be DC too, and that’s desirable since I dislike actively-switched LED lights — they tend to radiate RF and create radio noise. DC-only circuits generate very little RF noise. (Though not zero…) I didn’t want to have to use a heatsink, so that meant using a fairly heavy duty MosFET, and I had a few of these cheap 6R160C6 FETs lying around:

You can use any similar N-channel power FET in a TO247 package that has a 3 volt typical Vgsth and a breakdown voltage well over about 300V. When designing this, I decided to regulate the voltage being seen by the potentiometer R3. Normally I would put a 5.6V Zener diode there, but I didn’t have one, so I used the transistor Q1 instead. That works just as well, since accuracy is not too important. Here is the full schematic (click to enlarge). Note that this is just a “quick and dirty” circuit. For a more complex, but more reproducible circuit, see this article.

I carved up an old project box to make the controller. [And forgot to set the camera to “linear” mode when taking the picture, so it is slightly fisheyed]:

Mounting the LEDs is critical because each chip needs to be heatsinked (Is the right word “heatsunk” instead?). The option I chose was to solder the bigger pad of the chip directly to copper metal. I took a piece of 12 AWG solid copper wire and ran it through my jeweler’s mill, flattening it, until it was about 0.115 inches wide (3 mm), and cut it into 0.75 inch strips. If you don’t have a mill, then you will probably need to get some sheet copper (0.030 in or thinner) and cut it into strips using sheet metal shears. Here are photos. The copper strips also serve as a way to conduct heat to the chip for soldering, as you’ll see in the video. You can use brass instead — in fact, it would probably be a better choice, though maybe more expensive.

The rest of the assembly, test, and demo is covered in the video below. In general, this was an insane project! It took HOURS to make all the little LED elements and mount them right. However I had lots of fun and my piano light is everything I could want. Warning: my video is hardly edited at all, and I’m 71 years old and have a bit of hand tremor which is a little distracting perhaps, and also, at the end I play a few seconds of piano (Bach Fugue in D minor BWV565) and I’m sorry to say I did a terrible job of it. I can play that piece correctly (if not well…) — as long as I’m not being recorded! If you are crazy enough to want to duplicate this project, I’ll be glad to answer questions. Otherwise, when you build furniture, think ahead so it can accommodate commercially available lighting strips and you don’t end up having to make your own! 🙂

Below is the finished piano assembly, with the lid open to show the internal music stand. One other feature that I’ve not mentioned is the music holder — closing the lid would otherwise let the sheet music fall onto the keys. The metal bar visible at the top is a length of aluminum attached to two Neodymium magnets, being temporarily held to two steel washers glued to the wood. Before closing the lid, I pull the magnet bar off there and move it to the two large steel fender washers on either side of the music. The bar then holds all the music sheets snug against the wood when the lid is down. The magnets were harvested from some old hard disk drives — they’re strong! The magnet bar can hold quite a bit of weight. An earlier try used weaker magnets and was not strong enough. I had considered using a mechanical music holder of some sort, but I like how simple this method is.