how to dim 230v COB LEDs?

[kåre]

hey!
this is my first post,so please be gentle. (im sorry if im posting where i shouldnt!)
im currently building an armature for my tabacco inside grow-tent,and i really need a dimmer. there are 14 COBs drawing about 320w over 230v mains.
the frame is of aluminium and wood. planning to change out the wood for angled alu due to heat. i have also attached some small heatsinks and will add two PC fans for cooling the LEDs and circulation.

any thoughts about my design?
i also would like to build the dimmer myself,if thats even an option. im not very skilled but am always looking for new stuff to learn! what ive gathered so far,is that i need a constant current driver,i think. i tried with a several motor/heating element controllers but as im sure you'all know- no bueno!
i have much of what i think i need for something like this.

im very much looking forward to hear back for one or two of yous!
thanks in advance.

 

[Nigel Goodwin]

If the LED's are 230V, then they already have some kind of power supply internally, to reduce the mains voltage to whatever they need - the exact type of internal supply can either be dimmed or not, no point trying to dim one that can't be dimmed.

Why not just turn some of the LED's ON or OFF? Half the LED's turned OFF is 50% dimming.

 

[rjenkinsgb]

Can you post the exact type of lamp you are using? Or, if they have external "transformers", the type of transformer?

ie. The manufacturers name and model number, for whichever operates on 230V.

Photos of the labels could also help?

 

[Tony Stewart]

Radiating light without conducting heat in an enclosed space with COB's that are likely undimmable, needs a bit more info to define all the requirements.

Watts of radiated light =
Watts of heat max =
Temperature requirements=
room size.=

Designing with these requirements and more ( wavelengths , often helps getting it right the 1st time.

 

[kåre]

WOW! not a single proper response! fantastic!!!
thanks.

 

[Nigel Goodwin]

WOW! not a single proper response! fantastic!!!
thanks.

To get a proper response you need to ask a proper question - you still haven't told us if your lights are dimmable or not?.

 

[ZipZapOuch]

WOW! not a single proper response! fantastic!!!
thanks.

Your question was akin to me asking you for driving directions to my doctors office. There are a lot of designs in converting the 230vac to low voltage DC used by the individual LEDs on the lamp. There are also questions of how the LEDs are arranged and any type of storage (capacitors) on the lamp that would prevent using a PWM on an external switch (dimmer).

From my point of view, all the answers given were all the best proper answers that can be given - they were all attempt to collect additional information to finally give a proper answer. You can elect to quit and walk away because you don't have the motivation or knowledge to gather the information requested or you can participate in the dialog and data collection to get to your answer. Your call.

 

[Tony Stewart]

A power COB Lamp is unlikely to be dimmable, as this adds extra cost and is often not needed. Also, it conflicts with the requirement to make constant current low voltage DC with a tolerance range on Vac.

This would require internal modification or stating the problems you are attempting to avoid, such as heat rise.
Contrary to popular marketing info, LEDs do not radiate heat, but the LED internal resistance dissipates heat to the heatsink and metal casing which in turn radiates IR heat.

Your choices are limited to ventilation for heat removal or a better expectation for radiant illumination and power ventilation. Alternatively, you can use high-velocity muffin fans over the Lamp to remove the heat via an air duct with shared 12Vdc.

 

[christinescoms]

hey!
this is my first post,so please be gentle. (im sorry if im posting where i shouldnt!)
im currently building an armature for my tabacco inside grow-tent,and i really need a dimmer. there are 14 COBs drawing about 320w over 230v mains.
the frame is of aluminium and wood. planning to change out the wood for angled alu due to heat. i have also attached some small heatsinks and will add two PC fans for cooling the LEDs and circulation.

any thoughts about my design?
I'm also eager to delve into building the dimmer myself, possibly using Poppy Playtime Chapter 3 APK as a unique inspiration. Though I'm not highly skilled, I'm always up for learning new things! From my initial research, it seems a constant current driver might be necessary. I've experimented with various motor/heating element controllers, but as many of you may relate, the results were less than satisfactory. Fortunately, I have most of the components I believe are essential for a project like this. Any guidance or insights would be greatly appreciated!

im very much looking forward to hear back for one or two of yous!
thanks in advance.

I have a COB LED 50W Lamp Light 12V Circular LED Bulb powered by a 12V battery. I also have a ARDUINO MEGA 2560 (if needed). I would like to linearly increase the intensity through the COB LED with variable programmable time steps. This is used to simulate the sun rising light from dawn so i can't use PWM technics, just analogical. I can handle the programming but i need some help to figure out the hardware. Thank you very much

 

[Tony Stewart]

Sunrise is not linear. It might be more like this.

If you do not have an Arduino Uno or Due with a DAC, then but will need to use a PWM signal with a >20A logic level Nch FET on the low side to run cool.

Can you describe your function better with datasheets? V+ =? Heatsink =?

PWM is the most efficient way to switch and regulate current with current sensing so you have voltage-controlled average current using a Op Amp with current sense feedback.

 

[ZipZapOuch]

Sunrise will require an RGB LED because sunrise and sunset have way more red, yellow adds in quickly after the full disk comes above the horizon. By noon, you'll have a bunch more blue and a 6500K light source at about 1200w of radiant power per square meter.

 

[christinescoms]

Sunrise is not linear. It might be more like this.
View attachment 143382
If you do not have an Arduino Uno or Due with a DAC, then but will need to use a PWM signal with a >20A logic level Nch FET on the low side to run cool.

Can you describe your function better with datasheets? V+ =? Heatsink =?

PWM is the most efficient way to switch and regulate current with current sensing so you have voltage-controlled average current using a Op Amp with current sense feedback on dental clinics Tampa.

thank you so much for your suggestion