1W LEDs bulbs circuit equivalent to 60-70W Incandescent bulb brightness - Page 1
Forum section: electronics / beginners

author: Shivram10
author_rank: Contributor
timestamp: October 28, 2015, 07:23:47 pm
content: Hello everyone,I have a small onetime product photography project which is under a tight budget for eCommerce site for a friend, I have made a lightbox somewhat like this(image for reference only),now I wanted to build 2 softbox lights with 2 Nos. 60-70W and 1 Nos. 100W equivalent incandescent bulb brightness.(image for reference only)I have around 50-60 1W leds with heatsink, I also have aluminum pieces which can hold 18-20 1W LED. I wanted to use them for the project, its a one time project for few days so buying a professional setup is no use for me. I have searched online for schematic of LED Bulb I couldn't find any which are above 6W.If anyone can provide me a schematic for the above mentioned circuit it will be a great help.Regards,ShivramPS : - I am an amateur electronic hobbyist and I have limited knowledge of formulas for calculation of the input and output voltage, I can assemble a schematic though and I have most of the parts like Resistors, capacitors, LM317 Voltage Regulator etc lying around so I want to use them. I want to power directly via 220v AC mains if possible.

author: Seekonk
author_rank: Super Contributor
timestamp: October 28, 2015, 07:34:42 pm
content: Quick note. I would avoid any PWM dimmer circuits. A LED is quite fast and the pulsing of LED would give unpredictable results when mixed with shutter speeds.

author: Shivram10
author_rank: Contributor
timestamp: October 28, 2015, 07:38:38 pm
content: Quote from: Seekonk on October 28, 2015, 07:34:42 pmThanks for your reply,I don't want any dimmer circuit. I want constant bright light.

author: Nerull
author_rank: Frequent Contributor
timestamp: October 28, 2015, 11:52:30 pm
content: Why not just use off-the-shelf led bulbs in some small lamps? They're already ready to run off mains and available pretty much anywhere.

author: BravoV
author_rank: Super Contributor
timestamp: October 28, 2015, 11:56:18 pm
content: Quote from: Nerull on October 28, 2015, 11:52:30 pmThe op is from India, I'm guessing mains led bulb is still not popular there, or maybe they are still relatively expensive,

author: ivan747
author_rank: Super Contributor
timestamp: October 29, 2015, 12:26:58 am
content: Can't you rent the equipment?

author: IanB
author_rank: Super Contributor
timestamp: October 29, 2015, 12:29:59 am
content: Incandescent bulbs will give good colour rendition if you apply the appropriate colour correction in camera or in software as they have a continuous light spectrum with no gaps in it.LEDs may not give such good results (it will depend on the colour rendition index of the LED).So if you have access to incandescent lamps it may be advantageous to use them? If you have the camera on a tripod you can use longer shutter speeds to compensate for lower light intensity too.

author: nbritton
author_rank: Frequent Contributor
timestamp: October 29, 2015, 12:31:10 am
content: The problem that you're not thinking about is the CRI (Color Rendering Index) of those 1W LEDs will be extremely poor because they don't have the right phosphor for your application. They will make very poor quality studio lights, do not use them. You would be better off using a High CRI general purpose light bulb like the the Cree TW.What you really want is this:http://store.yujiintl.com/collections/frontpage/products/bc-series-cob-400l?variant=1424975617

author: nbritton
author_rank: Frequent Contributor
timestamp: October 29, 2015, 01:02:45 am
content: Quote from: Shivram10 on October 28, 2015, 07:23:47 pmThen go buy some LED light bulbs with easy open packaging at Home Depot and return them after your done, or re-use them in your home. Most bulbs are rated for 25,000 hours, but only come with a 3 year warranty (what's up with that?), so I don't think anyone will truly care if a few hours of their life gets used up.Again, I recommend a high CRI bulb but you also need to make sure the bulb has a high R9 value, these are hard to find in the stores. You can do an advanced search on lightingfacts.com to find the right bulb, but the easiest thing for me to tell you is to buy the Cree TW series bulbs. In fact, most any old incandescent bulb will give you better color rendering then a LED, so just go get some 50 cent incandescent bulbs. Although, with incandescents then you have to worry about the 2700K color temperature, and I don't think the Cree TW bulbs come in 5000K. Ugh, why do light bulbs have to be so complicated.http://www.lightingfacts.com/Productshttp://www.lightingfacts.com/cahttps://www.energystar.gov/productfinder/product/certified-light-bulbs/resultshttp://creebulb.com/products/standard-a-type/60-watt-replacement-tw-series-soft-white-led-bulbEdit: Ok I thought about what you should do and here is what I would do to get the color rendering and color temperature right for your budget lightbox. In the 60W lightbox I would use one regular 40W 2700K incandescent and one 40W 5000K+ LED, this should yield a high CRI / R9 light source with a neutral white 4000K color temperature. In the 100W lightbox I would use one regular 60W 2700K incandescent and one 60W 5000K+ LED. Then connect these to a standard dimmer switch so that you can adjust the lumens based on whatever your light meter needs.

author: Cliff Matthews
author_rank: Unknown
timestamp: October 29, 2015, 02:45:37 am
content: 12volt 50watt halogen bulbs are cheap and render nicely. Power 2 with an old PC supply (4 or 5 if you soft start them to deal with the cold filament current). Keep them away from the cardboard... Edit: Use your LED's for something else, a light box isn't likely to be on for hours. Since tungsten filament response is quite slow, you could try PWM dimming.

author: Shivram10
author_rank: Contributor
timestamp: October 29, 2015, 12:05:32 pm
content: Quote from: Nerull on October 28, 2015, 11:52:30 pmLED bulbs which are available in my area but are less than 10W and above 10W they have to get on order basis as they are expensive here.Quote from: AcHmed99 on October 29, 2015, 12:08:15 amThanks for the info, will look into that problem, I may as well use CFL bulbs as I have few in my home.Quote from: ivan747 on October 29, 2015, 12:26:58 amNo, renting is not possible.Quote from: IanB on October 29, 2015, 12:29:59 amI didn't go for incandescent bulbs because of heat issue.Quote from: nbritton on October 29, 2015, 12:31:10 amThese are good option but they will be expensive and getting where I live in India will time consuming and also as I said earlier its a onetime project so after that the LED lights will be useless to me after the project.Quote from: nbritton on October 29, 2015, 01:02:45 amI'm from India there is no Home Depot here. Thank you for the reference website lightingfacts.com, I will look into that.Quote from: Cliff Matthews on October 29, 2015, 02:45:37 am@Cliff Matthews, Thanks for the idea, I will go and inquire at my local shops for halogen bulbs.

author: hayatepilot
author_rank: Frequent Contributor
timestamp: October 29, 2015, 01:19:28 pm
content: Quote from: Shivram10 on October 29, 2015, 12:05:32 pmIsn't a 10W LED bulb equivalent to a 60-70W incandescent bulb?Wouldn't that be exactly what you need?Greetings

author: Cliff Matthews
author_rank: Unknown
timestamp: October 29, 2015, 01:36:31 pm
content: It's a light box, so CRI and cost is are priorities. LED's with high CRI are very costly and not easily available.

author: IanB
author_rank: Super Contributor
timestamp: October 29, 2015, 02:54:19 pm
content: Quote from: Shivram10 on October 29, 2015, 12:05:32 pmWhen comparing lamps for equivalent brightness you should look at the lumens not the watts. A 10 watt LED is very bright.

author: hayatepilot
author_rank: Frequent Contributor
timestamp: October 29, 2015, 03:00:17 pm
content: Quote from: Cliff Matthews on October 29, 2015, 01:36:31 pmhttp://creebulb.com/Content/downloads/product_info/40w60w_tw_product_info.pdfCree 60W replacement TW Series. 93CRI, about as high as LEDs go.10 bucks on amazon....http://www.amazon.com/Cree-Equivalent-White-Series-Dimmable/dp/B00H27TDSYSo at there are reasonably priced High CRI LED bulbs available. If one can get those in india, I don't know.Greetings

author: Cliff Matthews
author_rank: Unknown
timestamp: October 29, 2015, 04:01:56 pm
content: I used to get a blister pack of two 50w halogen's for a dollar. Now the successful Indian guy at the local dollar store wants $1.50 (likely more now, since I haven't bought any in a few months).BTW, 2 to 4 of these are great to quick test a PC power supply since they fit snug down beside the pins of a molex connector across black-red and black-yellow for around 65-watts of load.

author: nbritton
author_rank: Frequent Contributor
timestamp: October 29, 2015, 09:23:10 pm
content: LED bulbs have higher lumens per watt, so a 10 watt LED bulb is equivalent to a 60 watt incandescent. Do the product boxes there in India not show their equivalency rating?I've found you can get better color rendering if you mix 2700K and 5000K bulbs together. I do this in my bathroom, I have six fixtures so I use three 2700K LEDs and three 5000K LEDs with alternating spacing. It looks odd but it produces good quality light.