Have you had a bad experience with using low-cost power supplies?

Do we have any other choice? Most power supplies on the market are cheap, and most are pulsed. Resellers really do a bad job on this.

In general, most cheap supplies, and even the expensive ones emit lots of interference.

That's why I manufacture only analogue supplies with deep conditioning.

Other issues with cheap supplies are less obvious. Most waste energy. Including for producing noise both by radio waves and sound. But you have no way of knowing the efficiency from their documentation beforehand.

All this is true both for home and industrial use.

One particular power supply bothers me a lot. It is industrial. I presume a few hundred watts. The neighbouring company behind the wall pretends it does not exist every time I go to complain. But it is there. I know it, because it hums so annoyingly. It is not particularly loud. But loud enough to be audible. It is a relief when they switch it off.

Hi Andrew,

Thank you for your reply to this question.

Like most things in life, you get what you pay for.

Cheap power supplies are prone to early field failures and many times do not meet their published specifications.

It turns out that most modern power supplies are switch-mode and indeed they include internal solid state switching devices.

However, Safety and EMI specifications require that they contain any electrical noise via the use of built-in EMI filters and other techniques.

Switchmode power supplies are far smaller, lighter weight, and much more efficient than older analog types.

In fact, due the international Green Initiatives, analog power supplies are being replaced by switchmode types.

Here is a link to an article that compares Switchmode to Analog Power Supplies:

http://power-topics.blogspot.com/2007/08/linear-vs-switch-mode-power-supplies.html

Regarding the annoying "Hum" sounds coming from beyond your neighbor’s wall; this is most likely their local power distribution transformer and not a power supply. Here is an article that addresses this issue:

Re: Why do transformers hum?

http://www.madsci.org/posts/archives/2001-08/999309215.Eg.r.html

Hope the above is of assistance to you

Hi Andrew,

Thank you for your reply to this question.

Like most things in life, you get what you pay for.

Cheap power supplies are prone to early field failures and many times do not meet their published specifications.

It turns out that most modern power supplies are switch-mode and indeed they include internal solid state switching devices.

However, Safety and EMI specifications require that they contain any electrical noise via the use of built-in EMI filters and other techniques.

Switchmode power supplies are far smaller, lighter weight, and much more efficient than older analog types.

In fact, due the international Green Initiatives, analog power supplies are being replaced by switchmode types.

Here is a link to an article that compares Switchmode to Analog Power Supplies:

http://power-topics.blogspot.com/2007/08/linear-vs-switch-mode-power-supplies.html

Regarding the annoying "Hum" sounds coming from beyond your neighbor’s wall; this is most likely their local power distribution transformer and not a power supply. Here is an article that addresses this issue:

Re: Why do transformers hum?

http://www.madsci.org/posts/archives/2001-08/999309215.Eg.r.html

Hope the above is of assistance to you