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Choose
a power supply whose specifications actually mean something
!
When you need to buy a general purpose dc power supply,
there are a bewildering number of manufacturers to choose
from.
When you read the specifications they all look much the
same. Most quote load regulation figures of around 0.01%.
Some quote a volt meter accuracy better than your DMM.
In practise, however, these figures are almost meaningless
because they omit the essential feature needed to achieve
high accuracy and good load regulation - remote sensing.
Even the best known names in the business omit remote sense
from their lower cost power supplies - so does it really
matter ?
Remote Sense - do you really need it ?
 Well
it depends upon your application. If you’re working at very
low currents then probably not.
If you don’t need to know the voltage at the load
accurately, then possibly not.
What may not be obvious is how poorly regulated and
inaccurate a power supply without remote sense can become.
A two metre length of a 24/0.2 wire pair has a resistance of
around 0.1 Ohms. For a 5V load drawing 3A the metering error
without remote sense would be 0.3V with an effective full
current load regulation of 6%.
It makes a nonsense of specifications such as 0.01%.
Even the more basic TTi power supplies, such as the EL-R and
EX-R series shown above, have remote sense capability. You
can choose local or remote sense at the flick of a switch -
so if you don’t need it, you don’t use it.
Back to the TTi lab power supply range. |
