Chanon Wangtrirat Posted October 7, 2014 Share Posted October 7, 2014 (edited) Hi! guys. I have recently just made LED fixture to use on my work. Just cost me to make about $160. Output similar to 800W softbox. Made out from RGB ribbon LED and Warm-white ribbon LED. I expected to use WW LEDs at full power but eventually it drags down the color rendition made skintone look off. But the downside : It has multi shadow. solve sometime by using some diffusion sheet. Reason I chose this method. These LEDs are very abundant and very easy to find at cheap. But as you know you can't expect to have excellent color on this either alone. They are just good but I can toss-off for functionality that I gain from this thing. WW LEDs is to make broad spectrum base for skintone. RGB LEDS is to correct portion to matched the sensitivity of the camera. This approach is very similar to Arri L7-C fresnel light which used light engine they called to make tuneable light. While Blue LED have very high energy level. I chose WW LEDs which have high energy in orange green and red part. So I can added by RGB LEDs later to achieve Daylight. MY Goal : - Dimmable - Variable CCT - Green, Magenta shift - Color effect - Rock stady at any shutter speed from top to bottom. - Custom / Preset Switch - WW LED intensity - Red LED intensity - Green LED intensity - Blue LED intensity - On / Off switch Custom / Preset is to switch between selector which will used Pre-tunes trimpots that corresponds to each CCT and the accessible knob that can be customise as your favour. Preset knob is 4 position Selector switch connect to Bunch of Trimpots responsible for each channel. - 5500K Daylight (Tune to closely matched to Kino-Flo color as I have one for evaluate test) - 5000K Daylight (Tune to matched to Philips TL-D 950 Graphica as it have ability to mix very well with natural daylight) - 3200K Tungsten - 2700K Incandescent I just ordered Arduino kits and LCD. Maybe I can bring this into digital control like Kino Flo Celeb line. I just expect to using them without PWM modulation dimming. Here is the test. With Faithful picture style on Canon 60D. 5500K Kino-Flo True-matched Tune. 5500K WB 5000K Tune to Philips Graphica TL-D 950. 5000K WB 3200K Tungsten. 3200K WB 2700K Incandescent. 2700K WB Here are some test. Place like beauty dish. WB : 5500KCanon 550D + 18-55mmISO 800 28mm F4.0 1/60 e I just sharing my though. Maybe something just wrong approach for using these kind of instrument. But it just worked!!!! quite amazingly. Any suggestions very appreciated. Thank you. Edited October 7, 2014 by Chanon Wangtrirat Link to comment Share on other sites More sharing options...
Chanon Wangtrirat Posted October 7, 2014 Author Share Posted October 7, 2014 Custom / Preset switch LED Array. 5500K/5000K/3200K/2700K Shot at 5500K WB Link to comment Share on other sites More sharing options...
Premium Member Miguel Angel Posted October 7, 2014 Premium Member Share Posted October 7, 2014 It looks great!I really love it! :) Link to comment Share on other sites More sharing options...
Premium Member Phil Rhodes Posted October 7, 2014 Premium Member Share Posted October 7, 2014 The 2014 Nobel Prize in physics was awarded to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura today, in recognition of their work in the development of the blue LED. P Link to comment Share on other sites More sharing options...
Chanon Wangtrirat Posted October 8, 2014 Author Share Posted October 8, 2014 (edited) The 2014 Nobel Prize in physics was awarded to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura today, in recognition of their work in the development of the blue LED. P Yes, Blue LED is the game changer. We can't walk to this point if there is no Blue LED!!!! Another technology that I think it's innovative is the UV violet LEDs. Manufacturer called Yuji Beiling international make this. Instead of Blue chip excited phosphor to make white light. They used Violet UV LED to excited Red-Green-Blue phosphor resulting in more controlled color spectral output. . http://www.yujiintl.com/high-tlci-led I have called them and guess what???? one of the customer of them is Kino-Flo. Using there LED to make Celeb LED light. As seen in Kino-Flo Celeb video For now I can't effort to buy those LEDs. It's too expensive to make just this one but I think if it made up. With CRI and TLCI up to 97. Ridiculously excellent color rendition. They make conventional 5mm LED used on Litepanel 1X1 but with Blue LED CRI up to 90 too. Also Ribbon 5050 LEDs with High CRI / TLCI Violet Chip LEDs. Edited October 8, 2014 by Chanon Wangtrirat Link to comment Share on other sites More sharing options...
John E Clark Posted October 8, 2014 Share Posted October 8, 2014 Do you have a parts list... looks like you used 10 strips of RGB and WW LEDS, with about 2'x3' housing. I'm in to the DIY projects... Link to comment Share on other sites More sharing options...
Chanon Wangtrirat Posted October 8, 2014 Author Share Posted October 8, 2014 (edited) Do you have a parts list... looks like you used 10 strips of RGB and WW LEDS, with about 2'x3' housing. I'm in to the DIY projects... I think I can remember it. - 5M of RGB Ribbon. (But I think 5m x2 will be better as it has to be fighting against WW LEDS intensity.) - 5M of WW Ribbon or hard rigid WW LEDs. (If you can find one with higher color rendering it will be lower for RGB to correct color.) - 5mm Corrugated board similar to Diva-lite. (I think double the RGB LEDs will take some more space than I did.) - 7A 12v PSU - AC cord. (or using power brick. As mine is integrated into back of the unit already.) - Plexiglass I used 1x1ft 2 pcs to make front protection. - MDF as backplate to reinforced the structure. - Aluminium box (I used as a main structure to attach to light stand adaptor made from Flash stand mount. All electronic are enclosed in here.) - Some nots, washers and screws. Electronic part. You can use DC-DC Buck converter for 4 of them which provided more precise adjustment or simple transistor dimmer circuit. My unit consist of - 4 knob and potentiometers. - 8x 13007 NPN transistor - 4 Positions selector switch. - 13 trimpots for 4 presets. 3 for each RGB channel x4 and 1 for WW LEDs at constant intensity throughout 4 presets. - 4 Relays for switching between Preset and Custom. - 2 jog switch for on/off and preset. this is totally depends on part and method to control light output. I will do second unit soon which will double the RGB ribbons to increase intensity to fight WW LEDs. Arduino just arrived today maybe I can do something with it. Notice : The LED dimmer on the eBay and most market today is PWM dimming circuit. Which cause flickering on the camera even at 1/50 shutter speed because it's not operate on any of household frequency at all. The buck DC-DC converter is the way to go for now. Using this complex method to achieve white light. On the other hand Arri L7-C have micro processor that monitoring and calibrate the light color output. My Diy light have to be monitor and calibrated the trimpot for optimum white light accuracy. This is totally have to take care some. But if you do right you will be happy with the result. Edited October 8, 2014 by Chanon Wangtrirat Link to comment Share on other sites More sharing options...
Premium Member Phil Rhodes Posted October 8, 2014 Premium Member Share Posted October 8, 2014 I've been looking for a way to control those cheap buck converters from a microprocessor for a while. I don't think most digipots will do it with sufficient resolution - most of them are only 7-bit, although you could bridge them out with fixed resistances to permit trimming in a smaller range. Digitally programmable LED drivers are usually PWM, which, as you correctly say, is not the right way to go. It's possible to build digitally-controlled switching power supplies, but it's not something I've ever felt like getting into. P Link to comment Share on other sites More sharing options...
Chanon Wangtrirat Posted October 8, 2014 Author Share Posted October 8, 2014 I've been looking for a way to control those cheap buck converters from a microprocessor for a while. I don't think most digipots will do it with sufficient resolution - most of them are only 7-bit, although you could bridge them out with fixed resistances to permit trimming in a smaller range. Digitally programmable LED drivers are usually PWM, which, as you correctly say, is not the right way to go. It's possible to build digitally-controlled switching power supplies, but it's not something I've ever felt like getting into. P Exactly a problem I am facing too. I wonder how those LEDs in the market that have digitised control system doing with controlling the power. Find it at cheapest method is the hardest thing. Link to comment Share on other sites More sharing options...
Premium Member Bill DiPietra Posted October 8, 2014 Premium Member Share Posted October 8, 2014 Very impressive. Link to comment Share on other sites More sharing options...
Premium Member Phil Rhodes Posted October 8, 2014 Premium Member Share Posted October 8, 2014 You could do it with a normal switching power supply controller. You'd need to have the microcontroller read the current across a sense resistor, probably using an external amplifier to get reasonable accuracy from a (for instance) 10-bit ADC. Then you could use a DAC to drive the sense input of the SMPS controller, and apply your mathematics in between. ...if you want to try and build that, you're welcome :) P Link to comment Share on other sites More sharing options...
Chanon Wangtrirat Posted October 9, 2014 Author Share Posted October 9, 2014 (edited) This is really interesting. The idea to program Arduino to control DMX 512 on this module. http://www.aliexpress.com/item/Free-Shipping-Hot-Sale-RGBW-DMX-Decoder-4CH-DMX512-LED-Driver-RGBW-Controller-DE-8015/1409426007.html They said it's PWM at 5KHz which is pretty nice for normal shutter speed or even high speed that don't exceed 1/5000 (maybe) I will be order one to try it. Here is some test from youtube. http://www.youtube.com/watch?v=ixfHxOnGJPI Edited October 9, 2014 by Chanon Wangtrirat Link to comment Share on other sites More sharing options...
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