Soft-start for mains LEDs?

[peterdeco1]

Hi Anand. I did this so long ago I forgot how. But I remember using a triac and diac configured as a lamp dimmer. It started as dim and gradually ramped up by charging a capacitor. I also remember one of my attempts blew everything up. Be careful. An exploding capacitor is like a firecracker with electrolyte inside.

[ardhuru]

Hi Peter, thanks for that information; now I know at least that its possible!

Do you have any tips at all, from whatever you can remember? Those would go a long way towards not re-inventing the wheel.

I'm familiar with triacs and phase control, as can be applied to incandescent bulbs, or resistive, or inductive loads. Its just that I cant figure out how to control something like these, to ramp up to full intensity spread over a few seconds. http://www.shopclues.com/philips-led...B&gclsrc=aw.ds

Regards,

Anand

[peterdeco1]

Sorry Anand. This was at least 20 years ago. All I remember is building a dimmer circuit and modifying the section that used the potentiometer to control the brightness. If I had to do it all over again, I would probably buy a dimmer and modify it. It's probably cheaper than buying all the parts and making it yourself.

[ardhuru]

Peter, LED lamps (bulbs) 20 years ago?

[peterdeco1]

Yes. In about 1980 a buddy of mine had a digital LED wristwatch, LED calculators and alarm clocks were becoming popular. Google it. LED's were around since the 70's.

[peterdeco1]

I'm sorry I wasn't clear in my original post. Of course I didn't do the brightness thing with an LED replacement bulb. It was to slowly start an AC motor but the same process would work with AC lighting.

[Jerson]

Hi Anand

The LED bulb which you speak about may be of the non-dimmable variety. These will turn on at a certain operating voltage. They are NOT dimmable.

There are other LED bulbs which are dimmable in the old-traditional way. These are a different breed altogether and you will find them on ebay/such

Techniques - I do remember seeing dedicated ICs for doing such kind of dimming from a phase angle dimmed voltage wave.

Jerson