Seoul Acriche AC DIY Bulb - Questions

[lostsoul01]

Hello!

So I decided to try to make a "bulb" in what I considered the easy way.

I took a base from an old circular tube flourescent bulb, a heatsink, and picked up a "Seoul Acriche 110VAC 2W LED" from superbrightleds.com

BTW: I have been very happy with my purchases from there.

A friend cut the tabs off the heatsink for me, and tapped some holes to screw the star down.

So, I don't think taking the easy way might have been the best way. It does work, but it gets HOT. I can touch the heatsink for about 2-3 seconds before I pull away. And at this point there is nothing between the star and heatsink. It's down tight, but that's it.

It was a cheap project though, only $10 total, plus some spare parts!

My house is 120V, so is there a different version I was supposed to pick up, or is this one within tolerance?

And if anyone's used these, do they just really get that hot?

Here's what I'm considering using it in. Nothing exciting. I have a light on in my hallway constantly, because otherwise I find myself switching on my hallway lights which are 2 26W CFLs. With this hallway light, I rarely turn on the CFLs. This light is currently a 3W CFL and is on 24x7.

Thanks for any tips or advice you might have. Or even warnings that I'm going to burn my house down.

Also, any suggestions for something to cover the top of the led, keeping it clean?

 

[blasterman]

Page 14 of the user manual here says the Acriche requires resistance, and a lot of it:

http://superbrightleds.com/pdfs/AX2200-01LF.pdf

Which may explain why yours is running so hot.

I've been really curious about these LEDs because their design would eliminate the need for dedicated drivers, but I otherwise have no familiarity with them. I still can't figure out how they don't flicker without a full wave rectifier circuit.

 

[lostsoul01]

From my understanding of the datasheet, a resistor is needed. But, that's why they sell it on the star, at a pre-configured setting, there is a surface mounted resistor on there. Unless I'm missing something :thinking:

I do have to agree, that's what sold me on trying this one out. Basically all I had to do was figure a good way to get power to it, and that's that.

The output is nothing impressive compared to what is out there today, but then again it isn't quite apples to apples since you don't have to convert AC to DC since they do that for you with its setup.

Thanks!

 

[Ken_McE]

Worthy project, intriguing result. It sounds like it is running too hot though. Can you improve the heat sink, maybe attach fins or wires to it to increase surface area or improve the airflow or something?

 

[lostsoul01]

I have three thoughts...

1) I figure out how to use this copper core heatsink with it. It's heavy and I'm worried about the cheap plastic socket not being able to support it. If this were new I wouldn't go this route because it probably costs much more than the LED itself. That is backwards to me.

2) Find a small AC fan. I don't really want to do that because the fan will make noise and wear out.

3) Figure out how to lower the current or voltage to the LED and drive it at maybe 100V or 110V AC rather than 120V AC. Even if I were to underdrive it, that would be fine as long as it stayed cooler. Can I do this with a simple resistor addition onto the star even though it is AC? I'd think so, but I haven't looked into it yet.

 

[lostsoul01]

Wow, I do feel bad now.

Seems that someone has already done the exact same thing over a year ago!

120VAC LEDs
http://www.candlepowerforums.com/vb/showthread.php?t=171466

They noted the temp was about 80 degrees which seems about right.

"Measured the temperature on the heatsink using an Infrared Thermometer, after it had been on for 15 or 20 minutes. The temperature is about 80-degrees Celsius (175-degrees F). The maximum operating temperature per their datasheet is 85-degrees Celsius."

So I guess it is set up right, I just need to get it cooler. Thanks again for your time.

 

[blasterman]

(scratches head)

My Cree Warm-Whites when driven at 1.5watts would get that heat-sink warm, but not hot to the touch.

Active cooling will obviously solve the problem here, but why would the acriche be designed to reguire such dramatic cooling in the first place?

 

[piaf]

I was just looking for the Acriche for powering some stuff at home (Here with 230V) and found out this thread.

I believe there are two main reasons for such a high temperature:

- The LED is running with a higger voltaged then specified. Assuming the circuit would be a pure resistance, at 110V it would consume about 2,2W (or 2W as in the specs), with 120V around 2,6W and if the Power Company is providing you 130V (what usually happens here) it would be almost 3,1W.
However the specs for your LED states a maximum of 127V and 4.3W . So quite above my calculated values.

- In a regular LED you have the power spent by the led (1,5W) and then a bit more power spent on the the Driver and Power Adapter. In your case the complete power dissipation is done on the same spot. So leading to a higher demand on the heatsink.

 

[spencer]

I have seen somewhere close ups of this LED. There are something like 30 dies in it. There are two strings with a diode at the end. When the power is going one way one string lights up and the diode prevents reverse current from going to the other string. When the power is going the other way the reverse happens.