Diy psu?

[chowder]

Have any of you ever designed/built your own switching power supply? I'm (slowly) learning about the theory, but wondered if any more knowledgeable members here had ever built their own.

If such a thing is feasible (I'm unsure about sourcing suitable transformers etc), it would be cool to have some "BCN approved" PSU designs for modest power requirements.

Just interested to hear peoples' thoughts, feel free to shoot it down if it's impractical or whatever

[mariushm]

Re: Diy psu?

The certifications and tests required to pass before being able to put such a product to market can cost in excess of thousands if not tens of thousands of dollars.. that's why most companies just buy wallwart adapters from OEM manufacturers instead of making their own.

Those OEM manufacturers have the equipment required to test their products in-house before submitting them to certification laboratories and basically make sure they won't fail tests and therefore pay as little as possible, and they also buy components in volume high enough to be competitive or even manufacture the transformers and cases in-house.

There's fewer requirements to sell a DC input only / low voltage product.

In other words, it's fairly easy to make a switching power supply, plenty of ICs out there and plenty of datasheets for them with example circuits.

Take for example those ICs used in ATX power supplies for the 5v stand-by (for example LNK306 TNY278 etc) , you can read the datasheets for those chips and compare the example schematic with how the circuit is layed out on a computer power supply pcb.

[everell]

Re: Diy psu?

Most "cheap" power supplies use a simple two transistor 5vsb circuit. With age, they often go overvoltage and kill computer motherboards, more specifically, the south bridge chip. I have made several different outboard 5vsb circuits using different chips. They are easy to build and fun to play with. So you might start with a simple project.....find an old power supply with a two transistor circuit. Gut the two transistor circuit. Use the existing transformer and output regulation circuit. See what you can come up with. I have made many with the DM311 and VIPer 22 chips.