Elliott Sound Products (ESP) in Australia have posted some interesting articles on the web site:
http://sound.westhost.com/counterfeit.htmhttp://sound.westhost.com/articles.htmhttp://sound.westhost.com/articles/50-60hz.htmhttp://sound.westhost.com/articles/inrush.htmhttp://sound.westhost.com/psu-wiring.htmBuilding low voltage power supplies is an art. Many of the common linear regulators available from hobby shops will function in under 5 volt voltage power supplies. When read in conjunction with the manufacturer’s specifications, those regulators are really operating at their voltage limitations and may not deliver the full rated current.
I have a number of under 5 volt power supplies salvaged from laptops and mobile phone equipment. The mains supply is a switched mode power supply. The regulator used in the secondary low voltage side is a specialised under 5 volt voltage regulator not available to hobbyists. The low voltage side contains an opto feedback to the mains switched mode regulator. The combination of both produces the compact power supplies we see advertised on manufacturer’s sites.
There is nothing wrong with third party power supplies obtained from a legitimate source. In some cases they are identical in design to the original. In fact most manufacturers use a certified OEM manufacturer to manufacture their power supplies.
In my region, Australia, Liteon branded switched mode power supplies are commonly supplied with manufacturer branded laptops and notebooks.
http://en.wikipedia.org/wiki/Lite-OnWhere the problem arises is counterfeited electronic components and power supplies. Most are manufactured in China and replicate genuine power supplies down to the certification labels. They are always sold on eBay at almost give away prices.
The problem with counterfeited electronic components is that they will perform the job for a limited time. Considering there is no warranty on the product, that cheap power supply can work out to be an expensive long term investment.
There are plenty of posts on this forum regarding people asking for help building a power supply. No offence intended; the days of building hobby equipment is defunct. There is no way that a hobbyist can design and build a linear or switched mode power supply comparable to the genuine manufacturer’s product. Even if you can purchase the correct components, in most cases the cost of the components is more than purchasing a ready built product.
Most forums are international. The only reliable way to determine whether a power supply is genuine and suitable for your region is to ask a forum member who lives in the same region.
