Testing a psu

[scaesic]

Once you have built an ac traffo/rectifier psu, can you test it with your meter on the +/- terminals with an open circuit?
or is it better to have a resister as a test load and measure the voltage drop across the resistor?

is it just a case of p=v^2/r to work out the power disiopated in the resistor?

[petemoore]

  depending on how stiff the supply is and how much current...but for small signal circuits, sag can be mostly disregarded.
  Regulators need  a load to work, IIRC something like 10k.