[plug] Wanted: home for 8-port 10/100 switch, no PSU

[Paul Antoine]

The trick with switchmodes is to over-specify them.  A switchmode 
without a fan must be de-rated to 50% of its output... fan failures and 
over-heating of the capacitors are the primary drivers of switchmode 
failure in my experience.  PC supplies are often run close to ratings 
and have poor (read very cheap) fans.

I've had few problems since I started using 450-550W PC supplies with 
large 120mm fans.  The fans spin slower for the same air movement 
reducing wear on bearings.

Linear power supplies have similar problems... the capacitor will dry 
out faster if it runs warm.

The tiny high-frequency switchmode wall plug supplies are great in my 
experience.  I have ancient Nokia charger supplies which seem to just 
keep going forever.

Your mileage may vary...
P.


Kevin Shackleton wrote:
> I skipped a cheaper Altronics unit because it was a switching supply.
> Though they are cheaper, more efficient, more versatile etc they are
> also much less reliable than a linear (i.e. a transformer-driven)
> supply.  Physically larger switching supplies such as PC PSUs are better
> but still they are a significant cause of PC failures.
> 
> K.
> 
> On Wed, 2009-08-05 at 22:26 +0800, Michael Holland wrote:
>> No need to go that far. Its only  a few dollars on ebay.
>>
>> http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=200369377726
>>
>> Worth keeping a spare handy.
>>
>> 2009/8/5 Kevin Shackleton <kevins at reachnet.com.au>
>>         Easiest for the likes of us is to patch it to a discarded PC
>>         power
>>         supply unit.  The PSU should not be within reach of people who
>>         like to
>>         put paper clips through slots!  Or Altronics M9274 $21.95.
>>         
>>         K.
>>         
>>         
>>         On Wed, 2009-08-05 at 18:42 +0800, Leon Brooks wrote:
>>         > Needs 12V 1A through a small circular plug. Will hit the
>>         > recyclers Friday if not claimed beforehand.
>>         >
>>         > Handy to collect from East Perth but other arrangements
>>         > can be made if needed.
>>         >
>>         > Cheers; Leon
>>         >
>>
> 
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