Hey Guys,

Can anyone share some great instruction document on how to design transformer less power supply circuits please? Also, if you have a Proteus circuit simulation of a similar design would appreciate that too.

Thanks!!

 

Hi,
What current levels are required for the LED's?
E

 

Hi,
What current levels are required for the LED's?
E

Opps I am sorry. i am looking at about say, 300mA. I am thinking of having 4 parallel sets of 28pcs of series 2835 LEDs. each one is about 0.2W so i calculate about 240mA for all. Hope this is correct. And I think I would need about 93Vdc for this. So i need to know how to design the power supply for powering this... Thanks..

 

By "transformerless", are you thinking of a buck regulator, or a capacitive dropper?
For a buck regulator, it's simply a matter of choosing an IC and connecting it as per the datasheet.
For a capacitive dropper, first, bear in mind that the mains current will be the same as the LED current, so 300mA through the LEDs requires 300mA from the mains. Wire up 20 of those and you have overloaded a 6A lighting circuit.
Having said that, work out the series impedance that you need, work out the capacitance you need for that impedance at your mains frequency, and make sure that the capacitor has adequate voltage rating (for 230V AC that will require a class-X part)
You also need a small series resistor to protect against surges when the capacitor is first switched on.
Oh - and in either case - don't stick your fingers in it - it will hurt.