>Plenty, just look up LED driver ICs, using a search engine. Here's one example. Many more exist.
>http://www.mouser.com/ds/2/302/SSL21082AT-843512.pdf
Existence of drivers does not prove that they are used in low end LED bulbs. You can more or less count on that. BTW you are showing one which for sure will work with "PWM dimmable square wave inverter"
>Possibly. It would certainly exceed the ripple rating of the input capacitor.
Ripple rating of the input capacitor? BS. This lesson comes from bigclive LED academy? Crude LED bulbs have that poor series resistor for exactly that reason. - To reduce EMI and obviously ripple [inrush] current spike when minimum forward voltage of LED string is reached (check IV curve of the led). Most "dumb" LED bulbs conduct quite late in the AC cycle. Also we shall take in account that peak voltage of square wave inverter will be just 0.7x of AC mains peak for same RMS voltage output, so current spike difference could be minimal. In short - don't bother about wearing out capacitor or series resistor.
You seem to be somewhat confused. It's true the very cheap, low power lights use capacitive droppers, but when you are talking about a 10Watt LED lamp for a conventional lamp fitting then it is almost certain to be using a constant current switching regulator. I took apart some cheap GU4 bulbs recently and even those used a switching regulator.
If it has a bridge rectifier and smoothing cap, then any attempts to dim the LED through e.g. phase control or PWM will greatly increase the peak current through the rectifier and the ripple current through the smoothing cap.
The OP is not saving the world, he's trying to create a very complex solution to what appears to be a simple problem, and refuses to consider any other way of solving it.
I agree. Unless a special type of LED controller is used this won't work.
no worries with lowering of impedance here , smps bulbs only.people will be instructed to buy standard LEDs all are SMPS
... we specify make and watt
there are Khz frequency inverters in market , running LEDs for long periods.
power-slicing : i call it .....its the TDM ( time division multiplexing) of AC
Personally i try to avoid complexity in implementation. Bringing special chips for the job are last options.
I will use just 4017like sequencing ICs so that parts are available everywhere .
If you want to control the sequence of some lamps, then why not use a microcontroller? It will be more flexible than one of those old ICs and doesn't require as many components.
>Plenty, just look up LED driver ICs, using a search engine. Here's one example. Many more exist.
>http://www.mouser.com/ds/2/302/SSL21082AT-843512.pdf
i already have non-isolated driver based bulbs with similar chips . they too will be used in tests .
i may be noob here but Qn arises
where PWM dimming has come here ? we dont want to dim the lamps and reduce power .
we want same light for a much lesser power
If it was possible to produce the same light for less power, then don't you think the LED lamp manufacturers would have already done that?
Your scheme will not give you the same light for less power. It will use more power to give you the same light and poorer reliability or slightly less power for much less light, again with poorer reliability.
Simply switching the LEDs on and off at a high frequency will not lead to any increases in efficiency, even if such a scheme were compatible with the integrated driver electronics. The human eye perceives the average brightness of a light flashing at a high frequency. If you flash a 10W bulb at 1kHz, equal time on and off, it will appear to give off the same amount of light as a 5W bulb.
In practise, if you tried to do that with a ready made LED, with a constant current DC:DC converter, the results will be unpredictable. It might: produce the same brightness but draw double the current, causing potential reliability issues, flicker horribly or just be dimmer.
Another factor is the non-linear response of the human eye. A 5W lamp may not appear to be half as bright as a 10W lamp, so even if you think you're successful by using half the power, for a slight drop in apparent brightness, you'll find the 5W lamp would have been a better option.