EEVblog Electronics Community Forum

Electronics => Beginners => Topic started by: T3sl4co1l on June 03, 2016, 09:13:56 pm

Title: Warning Signs... (Caveat Emptor)
Post by: T3sl4co1l on June 03, 2016, 09:13:56 pm
If you're ever feeling uncertain about the quality of a product, you can always act on that feeling:

(http://seventransistorlabs.com/Images/CSMQ.png)

(http://seventransistorlabs.com/Images/CSMQ2.png)

Product in question, a 30V/5A switching supply, of the poorest quality China can supply (as I understand it).

Another warning sign (that came up in the IRC conversation that prompted the above message): if they don't state what bandwidth the ripple measurement includes.

This particular prize pony sports a lean 200mV of ripple.  No bandwidth or operating condition stated.

I can't imagine it'll last very long, either.  The bargain-basement linear supplies are bad enough...

(Not a burned customer -- I know much better than to bother! :-DD Just an FYI for "young players".)

Tim
Title: Re: Warning Signs... (Caveat Emptor)
Post by: tautech on June 03, 2016, 09:55:04 pm
  No bandwidth or operating condition stated.
Found similar on a small 30V 5A SMPS bench supply.....the only way confirmation of the manufacturers stated ripple specs could be met was with 20 MHz BW limit and Averaging turned on, when tested in that manner it easily met spec.  :phew:

Yet these little units have given me a couple of years in the field to date with no failures.  :popcorn:

As you say: Caveat Emptor