Small transformer 220v to 24v

Hello there,

I’m looking at those wireless light bulb’s, such as LIFX or Philips Hue. You just screw them into the regular socket of your lamp and off you go. I’m wondering how on earth they fit a 220v to 24v transformer in there. Guessing it’s the same as in the tiny smartphone chargers, whatever the technology is called.

Does anyone know all there is to know about that, and care to link to documantation on it? I haven’t a clue what to google for.

Even better, does anyone know where one might get a hand on some of those…?

That would probably contain a custom built switch mode power supply…

Thanks both!

Can’t use a capasitive power supply for anything more than a single 5mm normal LED. Anything more will waste WAY too much electricity.

Switch mode can be transformerless, while using an inductor(half of a transformer) but the in/out ratio is limited for an inductor only supply. Hence switch mode supplies running of 110V/220V generally have a small transformer, even if just to isolate the input mains from the user accessable output, like in smart phone chargers. By small I mean that the transformer can be as small as 10mm x 10mm x 10mm…

That is fine, but the original post was about the power supply inside a light bulb that took mains and outputs 24V for a light. You are looking at 250mA to 2A for a light, depending on wattage. That is way outside the comfort zone of a capacitive supply… :slight_smile:

BTW. I just googled both those lights mentioned in the first post. Both are RGB led lamps. Neither of them state the light output capacity or wattage. Both their websites are very flashy while saying very little… :frowning:

I have seen a really bad implimentation where they connect 10 white leds in series, rectify mains with a bridge, limit the current with a resistor. very bad… :slight_smile:

I think Maxim IC has a switching chip that they designed for 4W white leds that run of 220V. small circuit that fits in the base of the bulb…

Can’t find Maxim’s circuit, but found one from TI