SAFELY ballast a 400w LED cob set for under 20$

What youll need,
-4ct: 100w LEDs that use a voltage between 30-36v and draw about 3-3.5A at max power.
You won't be powering them this hot. You'll be powering them between 2-3A to preserve the life of the LEDs and not cook up your grow room in heat. I'm using some blurple EPISTARs here. But you could use 4ct whites or blues, or 6ct Reds if they're 20-26v

-small tube of thermal paste or silicone grease

-1ct: full wave bridge rectifier that can handle at least 200v and 6 amps to play it safe. these only cost about $1.50 on ebay (part# sk10254 is what im using here)
-1ct: 200uF AC Capacitor rated for a minimum of 125VAC. $2.50 on ebay literally just type in "200uF AC capacitor" DO NOT USE A DC CAPACITOR (for this at least.)
-1ct: 3.5A fast blo fuse, just get 10 to have them handy if you muck something up. do all your testing with a fuse in place so you dont burn out a 35$ LED. 10ct fuses on ebay are about $2.50.
-1ct: Fuse holder, these are $2.25 on ebay. they're just two electrodes that clamp a fuse in place and make for easy fuse replacing
-Enough heat control, this cost is on you. i gutted a poor ol' car amplifier for the two large heatsinks, i still need to add pc fans to keep it cooler. theyre in the mail right now.
-Red/Black hookup wire if you have it around. you can easily use any color just get solid core 16awg there-abouts
-Light switch... 69 cents at lowes
-Multimeter with a DC current setting
-solder/soldering iron
-damp paper towel
-AC cord with a ground plug that fits an outlet. the ground plug isn't actually necessary but helps maintain the location of the HOT terminal in the cord. The HOT terminal is the smaller of the two flat plugs. The NEUTRAL is the larger. GROUND is the circular plug part that tends to break off when fucking around.

So, let's build it.
Im purposefully not going into any detail other than a schematic because i do not want those uneducated in electricity to start here because they want to grow some dope for cheaper. Just buy a meanwell ballast if you dont know what your doing with a schematic. this one is is really easy to follow. just put the fuse on either the Hot or the Neutral wire, it really doesn't matter which but will protect your circuit during testing and if lightning strikes your power lines. ewww blurry

btw the 20$ limit is the ballast cost, not the LEDs and heatsinks. fyi

How safe is this when wiring up multiple cobs?

safe as long as the voltages add up to at least 120vDC

ive been using this one for a while now. its two seperate circuits on one panel so i can use only blues or only reds. but you could easily implement it to be whites. is that what you mean? you pretty much have to use at least 4 chips or theyll get burned out. when you link 4 chips in series the max operating voltage ranges from 120-144vDC. this circuit runs them at 95 when using a 100uF capacitor and 102ish when using a 200uF capacitor.

the grow light in my room was running on 100uF per spectrum until today when my order of 200uF arrived. i added a 200uF in parallel with the existing 100uF to make 300uF and the units respectively went from drawing 1.25a to 2.9a in the red spectrum and 1.15a to 2.2a in the blue spectrum.

if you used only one chip you would need to buy a transformer or a driver unfortunately. but if your trying to fill a room in this is a very cost effective way versus buying a driver for every chip.

What's with the series capacitor?

Very cool man, I'd love for someone knowledgeable about ballasts to give their opinion

Surely it can't be this easy?

What about wattage limitations or is having the correct voltage the only concern?

churchhaze said:

What's with the series capacitor?

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the series capacitor is on the AC of the circuit so it has an "reactance" which can be rated in ohms. it's like a current limiting resistor that won't get hot. the way it works is . as you can see in the formula, at some frequency, the capacitance "REACTS" and forms resistance. If you had put it in parallel, the voltage would have increased and you would blow up one or more LEDs. If you had left it out, your circuit would draw over 8 amps immediately and blow up just the same.

the capacitor will not work on the DC side of the bridge rectifier, because there is no frequency of switching positive and negative on the dc side. it would block all current and look like a huge megohm resistor.

C in the formula is rated in whole farads, so 200uF would plug in as .0002

follow?

Millsie said:

Very cool man, I'd love for someone knowledgeable about ballasts to give their opinion

Surely it can't be this easy?

What about wattage limitations or is having the correct voltage the only concern?

Click to expand...

the voltage is the only concern here, so if you had 4ct LEDs that were rated for 30-36v but only can HANDLE 1a (instead of my 3a i used) then the circuit would draw something less the 1a. this is a bit scarey to imagine but the current is dependent on the amount of voltage you give.

this triangle is commonly memorized table. it's just an artistic way of remembering what each part of the circuit will look like when given two of the others. they are all dependent on eachother.


but yes it is that easy. just read the max voltage range, buy four if theyre 30-36v, buy 6 if theyre 22-44v, or whatever gets the lower side to add up to 120ish.

this is the panel i use. it is two of the circuits i posted in the OP. one circuit for red one circuit for white/blue. i can just flip a switch to turn off one, the other, or both

with one 200uF capacitor you could theoretically parallel up to 9amps of these series circuits but theyll each only draw the required current it takes to get them to the voltage being supplied.

so if one series circuit is drawing only 2.2a then you could put 3 of these in parallel and end up with 12 LEDs fully functioning. you'd need a bridge rectifier made for at least 10 amps but it will work.


if your a power saving stickler that just wants to Get By you can skip the bridge rectifier and use another series circuit in parallel as the other but reversed in polarity.

what happens there is one series turns on, then the other, then back to the first, then the other, repeated 50-60 times a second. i used to just do it that way but it's a doozey to look at but can cover more surface area

im all of of coffeee!!!!!!!!

btw im an engineer by education and tinker/toymaker by practice

this cost $2 on ebay and can power 2 amps worth of 12v pc fans.

or you can use a 12v transformer and rectify the output for a more efficient energy transfer but at a higher cost since youll be paying for a lump of ferrite and copper.

Google Eli the iceman. I and e out of phase.

100% +rep to you. i forgot to mention the guy who brings the ice and sometimes new siblings oOoOo kidding. but yea. thats exactly how this works. we could do the same with inductors but would need a heavyweight .2 Henry inductor minimum and yea thatd be a bitch to mount. itd feel like a guitar amp hanging in the air.

dandyrandy said:

Google Eli the iceman. I and e out of phase.

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just who is ELI?? well he's the bringer of ICE. why am i capitalizing these letters?

for a PHYSICICSL representation. notice the inductor is a wire, so the current passes right through
or would at least if it werent limited by a repeatedly growing and collapsing magnetic field.

and a capacitor isnt actually making metalic contact at the electrodes, so you can see that current would be blocked but the voltage would pass if it weren't limited by a charge building and depletion repeatedly.

You could calculate the power factor but I'll stick with the cc supplies. I saw a Russian dude do something similar a couple years ago. I just have a tech degree and usaf electronic crypto school. The CPU was the size of a double fridge all TTL logic. Card punch, card reader, tape punch, rape reader and a page printer. 1200 baud. 1967.

dandyrandy said:

You could calculate the power factor but I'll stick with the cc supplies. I saw a Russian dude do something similar a couple years ago. I just have a tech degree and usaf electronic crypto school. The CPU was the size of a double fridge all TTL logic. Card punch, card reader, tape punch, rape reader and a page printer. 1200 baud. 1967.

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eww. lok

tech degrees are great!

We all have one! Well I am very close to one! Really good explanation of how the light works and functions! Nice breakdown dude, I am still tripping on the caps. The power supply unit can be built small and compacted. a small power supply set up would make it much easier to hide the supply and make the light safer to use and sell! Again very nice job with the explaination. Well after sitting at PJ for two hours with no power back to work. Btw it's 12:30am lol

Lol this shit is awesome!!

DocBry said:

Lol this shit is awesome!!

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thatd be and interesting way to journey into space ha

glad to see you're using the forum!