Hi I am working on a number of projects using LEDs to light areas of home, ideally I would like each device to have it's own efficient power supply like any consumer item

My projects include clocks, infrared detection, stationery lamps and "lightshows" around the house

The voltage demands are no more than 5v DC for ICs and around 3v for LEDs I have considered:

- bridge rectifier on custom wound transformer

- common 5v cell phone charger

I have been doing all my breadboarding using a 5v charger and it seems to work well but I am unsure about losses without cracking the thing open.. I can get these cheap and then design a buck converter from components I already have instead of building transformers, after all I don't anticipate to draw more than 100w watts in the entire home so I could just use a resistor..

Thanks

 

I have 2 tubs of wall warts that could be put to use... LEDs are not voltage devices except to overcome the forward voltage PN junction threshold. They are current devices. I've built several "custom" power supplies and can tell you they are usually cheaper to buy than to build unless you cannot find one that fits your required specifications. You are looking at it a bit backward. What is your voltage and power requirements? Find or design a power supply for it with a sufficient overhead allowance. That said, building a power supply from scratch is a good learning experience and handy knowledge to have.

 

I have been doing all my breadboarding using a 5v charger and it seems to work well but I am unsure about losses without cracking the thing open.. I can get these cheap and then design a buck converter from components I already have instead of building transformers, after all I don't anticipate to draw more than 100w watts in the entire home so I could just use a resistor..

I'd use USB chargers and not be so hung up on efficiency. USB chargers are going to be switching regulators. There are a lot of counterfeits, so caveat emptor.

If you need other voltages, second hand adapters are readily available. Laptop chargers will provide several amps at around 18V.

Most wall warts are going to be switching regulators because transformers are heavy and relatively expensive.

 

The most efficient is a switching current regulator such as one of these, since they don't use a resistance to control the LED current, but it may not be worth the cost for low power LEDs,