My Low Cost LED Power Supply

william chan

This circuit directly powers LEDs directly from 240v AC (110v should also be possible but half the current ) without transformers
and can supply up to 250mA to power 3 white 1watt LEDs in series without any need for ballast resistors.

This whole circuit can be embedded in a bulb form, to truly create a LED light bulb.

The circuit works, but it is not perfect.

Anybody can guess what's the weakness of this circuit?

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www.fd.com.my
www.mercedes.com.my

Sparks-R-Fun

The energy being consumed by D2 as it provides voltage regulation seems like a bit of a weakness if energy efficiency is a strong design goal.

Is that what you are thinking?

- Sparks

william chan

Actually D2 is not really conducting unless the LEDs become disconnected from the powersupply.
D2 is just there to prevent C4 from exploding when there is no load.
In this circuit, current regulation is the theme, not so much on voltage regulation.

Hint: If the bulb is screwed on not so tightly, a lot of big sparks will play out like fireworks.

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www.fd.com.my
www.mercedes.com.my

LoopyByteloose

Just a friendly reminder - without an isolation transformer, this circuit will possibly give you a dangerous electrical shock.

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PLEASE CONSIDER the following:

Do you want a quickly operational black box solution or the knowledge included therein?······

···················· Tropically,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan