Seoul Semiconductor SunLike 3030 LED testing

[hans]

I received the LEDs I ordered and soldered one of the 95+ CRI ones for evaluation.

product page
datasheet
Digi-Key

The larger cathode pad is soldered directly to a scrap of 1" x 1/8" solid copper busbar for heat dissipation. The procedure to solder it was:

• Stick LED workbench, solder side up, with foam tape.
• Apply a bit of solder to the pad with standard soldering iron. (Did not end up using the syringe of solder paste visible in the background.)
• Clip vise to hold busbar vertical resting gently on the solder blob on the cathode pad.
• Heat busbar with propane torch, removing heat as soon as the solder reflowed.
• Cool busbar with damp rag to avoid keeping the LED hot for longer than necessary.

IMG_20200722_211557.jpg (124.55 KiB) Viewed 3035 times

Applying power with a multimeter probe to make sure the LED still works:

IMG_20200722_214805.jpg (145.15 KiB) Viewed 3035 times

Anode wire held in place with packing tape and soldered:

IMG_20200722_222306.jpg (110.85 KiB) Viewed 3035 times

Halogen vs. LED:

IMG_20200722_235335.jpg (119.48 KiB) Viewed 3035 times

LED "installed" in the Microstar IV:

IMG_20200722_235634_1.jpg (135.04 KiB) Viewed 3035 times

The 4000K part I got is slightly warmer than the halogen with blue filter. I was going get 5000K also but they were out of stock at the time I ordered.

Based on linear RGB values from raw files from my Nikon D5100 the LED running at 1 W is giving roughly 2-3x brighter field than the 20 W halogen with blue filter. I don't have a good permanent photo setup yet, currently using the D5100 with DX NIKKOR 35mm f/1.8G handheld through the eyepiece. The brightness comparison shots were done in manual mode not changing anything about the microscope or camera setup except swinging out the halogen and moving the LED into position.

[MicroBob]

Hi Hans,
that is quite a nice LED type with an unusually even spectrum. The cold white version with a light yellow or skylight-b filter might offer a really nice light colour. In your photos it looks as if you were running it at 1A, not 1W though. The data sheet specifies a max. current of only 0,2A. That doesn't seem to fit together.

Bob

[hans]

Sorry, should have explained the tangle of clip leads... I am not using the current-limiting feature of the power supply since supplies not specifically designed as LED drivers or current sources generally have too much output capacitance which will deliver a surge of current directly to the load before the current limiting circuitry responds. Instead I have a 15 ohm resistor in series with the LED chosen to give ~200 mA with the 10 V maximum output of the supply. In the last photo the meter on the power supply is reading 9 V, the DMM is showing 150 mA, and the voltage across the LED (not being measured in the photo) is a little over 6 V.

I used the LED for an hour or so last night while continuing to mess with the alignment of the microscope and am pretty happy with the color, although as you say I think I would prefer the 5000 or 5700 K version, too bad they do not appear to be available from any distributor.

I also have a 5000 K, 90 CRI Samsung LH351D series part (SPHWHTL3DA0GF4RTS6) that I am going to solder in the same way for comparison. The spectrum is not as even at the SunLike 3030 but doesn't have as much of a gap above the blue peak as many others.