[sdiy] Testing a power supply

[John Luciani]

How involved to you want to get?

I would replace the dummy resistors with an active load
(see the active load schematic at http://tinyurl.com/6cbn6h)
This will allow you to easliy test under different loading conditions.
It is a very simple circuit.

The basic tests would be

  Line regulation which defines how a change in input voltage produces
  a change in output voltage

  Load regulation which defines how a change in output load produces
  a change in output voltage.

  Efficiency which is the ratio of output power to input power
  This can be difficult to measure with high accuracy.

  Output ripple AC component of the output voltage

You could also add dymanic tests and fault testing. Power supplies usually
have over-current and over-voltage fault modes that you test.

For a switching supply a basic test sequence would be ---

   Low Line, Max Load   (highest operating frequency)
   High Line,  Min Load  (lowest operating frequency)
   Nominal Line, Nominal Load
   Efficiency (nominal line, nominal load)
   Output ripple

For a linear supply I would add High Line, Max Load which would
produce the maximum heating in the linear regulator.

You could also perform the basic tests at different ambient temperatures.

(* jcl *)

-- 
http://www.luciani.org