Okay, Being that I got some cheap LED COBs, I am going to try to put something together. I was inspired by someone who used a muffin pan (sorry, can’t remember who is was togive credit) so I decided to go that route. Instead of using a regular muffin pan, I decided to go with a “Muffin Top” pan as it would allow me more room and have less “cup” to contain heat.
This is the pan. I decided to put the COBs inside the cups as they are not very deep and the bottom would allow for better attachment of cooling fans/heatsinks.
I will probably use 120MM fans but may incorporate this 300mm x 140mm x 20mm heatsink as well. Tghinking about cutting in half, lengthwise, and run over three cups.
The COB’s are 50W AC “driverless” that I got from a buddy of mine. He got them to repair a bunch of Security Lights and had these left over. I think I paid about $0.50 a piece. I have both 6000K and 3500K and my plan is to incorporate 4-3500K and 2-6000K into this light (question to follow)
And, of course, these will all be tied together with thes magnificent Wago connectors.
The plan is to have 6 COBs, 4-3500K and 2-6000K. This in mind, I have a question to the “Peanut Gallery”. Should I place the 6000K COBs on opposite ends, i.e.
6000K - 3500K - 3500K
3600K - 3500K - 6000K
or would it be better having both inthe middle, i.e.
Looks like they are yes. I saw a video where someone added a capacitor to one and the flickering stopped. They seemed to drive them unregulated though, but it was interesting to see
Yeah they’re Chinacrap AC Driverless. They are supposedly 50W each, so the total concievably be 300W. Going to mount the meter between the regulator and the fixture so I can get a close approximation for both Power and Energy.
What do you think of the arrangement of Cobs? Which do you think would be more effective.
My thought is to build a second one eventually but for the time being I need to make due with just the one for my 2.5’ x 2.5’ area.
I have seen these in action and while they do have a bit of flicker, it is pretty steady. I have seen the same video, I think, but I don’t think I am going to mess with that now.
I know everyone talks about the cheap Chinacrap, but I guess my buddy lucked out. He bought a gross, used 110 and only had 4 bad ones.
Im wishing you the best of luck with your project. It sounds like a very cost effective lighting option.
I do have one minor, pedantic, nit picky, little correction for you though. Electrical energy is measured in volts and amps. When it comes to the total energy or total power, that is almost always expressed as watts. Watts can be converted to other units - like horsepower, joules per second, etc, but watts is the standard unit for everyday usage. So the total power is the total watts - they are the same thing. There is no total ‘energy’ other than the watts.
The formula is volts times amps = watts. Watts is how electrical energy is usually calculated. You cannot directly measure watts. Any meter will actually be measuring volts and amps, and then do an internal calculation and display the result as watts.
If your meter claims to measure ‘power’ and ‘energy’ as separate things, that means who ever did the marketing or wrote the manual didnt know what they were talking about
Its also possible they are talking about watt-hours. Thats fairly common calculated number to display for this type of meter. Its even remotely possible they are displaying energy as joules - which would be mostly correct, but a joule is actually units of force over distance - usually in newton-meters. I doubt that though.
In any case, none of that is really important. Just focus on the volts, amps and watts and you will be fine. Those three are the key things you need to know.
Yes. It measures Volts, Amps, Power (Watts) and Energy (Watt Hours). If by turing down the volts, I would be reducing the watts, correct (as long as the amps remain the same, that is). My main concern is the amount of watts output and, for figuring cost, the watt hours.
No, I was a little confused until I pulled out an old E.E. textbook I had in the closet. I knew Power was Watts, but Energy threw me for a loop (studied Metallurgical Eng but had to take a Electrical class).
Hmm, normally LED intensity is reduced by turning down the amps rather than the volts. There will be a minimum start up amperage but most times it’s a fair bit less than the standard amps it designed to run at.
I assume however these driver-less cobs are are setup in an array of parallel/series stings to match mains volts and are just using a resistor to limit the amps? Typically the ones that use BP5123H chip linear driver or similar do this. IF so you could always replace that with a different one to reduce the brightness by limiting the current.
Yes, they are Driverless COBs. From talking to folks who have used them, I was told that this was the way to go. I may not even install the regulator in there, at the start, but all connections will be with wagos, so it will not be difficult to add later. I do knopw that there is no way in hell I want to mess around with adding/removing/exchanging resistors or anything else on them.
Have to wait to figure out what I want to do for cooling, and am tied down with a few projects around here (have to repair a busted sewer cleanout, build a ramp for the pooch [age is doing a number on him] and a few other cleanups from all the cutting down of trees we did) but will hopefully get started with soldering on the wires for the COBs and general layout of the setup itself.
So in the meantime, a query to the group. Am thinking about using either (3) 120mm fans or CPU Coolers (low profile preferably) and set either up between the opposite pair of “cups”. I would rather not have to use 6 of them, one on each “cup” if I don’t have to. I can also use both the Heatsink and (3) 120mm fans (centered on the 6 cups) OR split the Heatsink in half (lengthwise) and strtch it across the 3 cups and use 4-5 60mm fans per hatsink (per side). Is it better for many smaller fans or less larger fans?
Check this out, it’s a tear down/schematic of what are probably pretty similar chips to the one you are using.
Hopfully it helps.
Re fans. It’s all about air velocity of the air passing over the heat sink, So in general a faster, noisier fan is better.
The only real issue with lots of fans is that to be most efficient they require a reasonably laminar flow so lots of fans is likely to increase general turbulence and reduce cooling. Not by enough to worry you though. CPU heatsinks work well on COBS in my experience, as long as they have sufficient heat dissipation for the wattage you have them cranked at.
It’s funny, I subscribe to his channel. He has done a few videos on these type of COBs and was one of the reasons I went with the Voltage Regulator method for controlling them. Though, there were a few others.
My original idea was to use a few “larger” fans rather than a bunch of smaller fans. Didn’t think about turbulence, just figured the larger ones would have a higher CFM rating. The only advantage I saw with many smaller fans is that they would be closer to the source and might have been more effective.
Yeah, for what you are doing that would be fine I woudl think. The upside is they won’t be as loud. Interesting to know what the lumens/watt would be on these things. I can imagine they will be throwing out a bit of heat?
Am going to try to install one of those Lumens apps on my phone and see what I get when I start testing and put it all together. Anybody have any sugestions for a Android one?
Okay, I spend half my day doing stuff around here and the other half flat on my back, recuperating, but I have been able to do a little work on the light.
I was able to finish a template for setting the COBs in the cups (too tired to take a pic, so will have to post one tomorrow… or actually today). Depending on the weather, which doesn’t look good for now, I have to build a gate (at least a two day project), fill in multiple ruts from a stump grinder, build a ramp for the dog (tough being old AND having to go down two steps to take a crap) mow what little lawn (should say mostly weeds) that is left, clean out the garage (so I can actually get most of these done), get rid of all the crap the tree guys ripped out in order to get to the stumps AND get the yard repectible for a little get together of old friends of my sister’s. Thank god I have my sister and Brther-in-law MAYBE come over once a month (about an hour before sundown) to help get these done. But I hope to get some more done on the light today (PRAY FOR RAIN FOR ME).
This is a great way to test that guy out & see if he’s good enough for your sister. When my sisters fiance rode 2 hrs with my chain-smoking, chatty-cathy mom holding an injured, diahrea-spraying dog, to the emergency veterinarian, I told her “he’s a keeper”
Today (weds) and tomorrow are supposed to be dry so they will be gate building days, but hope to get the holes drilled and COBs soldered by the weekend. Will also have to drill holes for the cables (will probably drill them on the side of the cups where they meet the pan. Should allow for them to lie straight and will easily channel in the gaps between. Also will place all of the Wago connectors(4) on one end.
Now here is a question for the “Peanut Gallery”. If you are using normal COBs and a Driver, where do you ground to? I would assume that the drivers are 3-wire, Hot, Neutral and ground, on the AC side? With this, being that it will be AC the whole way, can I ground to the pan?
When my sisters fiance rode 2 hrs with my chain-smoking, chatty-cathy mom holding an injured, diahrea-spraying dog, to the emergency veterinarian, I told her “he’s a keeper” 
big brother
