Electronic – Is this the correct way to wire the transformer

safetytransformer

I am building a 12 V dual power supply. Since this is the first time I will be using mains (230 V). I would like to make sure that I am not going to burn down my house.

The transformer I want to use is this one in the 2×15 V, 30 VA rated version:
transformer wiring

For my power supply I would like to turn this into a 15-0-15 center-tapped transformer by:

  1. Connecting the primary windings together (grey + violet).
  2. Connecting the secondary windings together (yellow + black). This would be the center tap.
  3. Putting a 100 mA fuse before the primary winding (either blue or brown).
  4. Putting a 1 A fuse on each of the secondary windings (orange and red).
  5. Feeding these secondaries into a bridge rectifier, filter caps, and regulators.

Is there anything that I missed, or should be aware of before I get myself electrocuted?

Best Answer

A few thoughts come to mind:

  1. 15v secondary implies ~21v peak. So the differential across your regulator will be 9 volts. Quite large. If you are intending to use 30va at 12v, this implies 2.5Amp max. Which means 2.5 x 9 = 22 watts in your regulator. But with max < 1amp (based on your fuse) this is lower, but still high.

However if it's a inductive buck regulator, then less of an issue.

  1. Center-tap transformer does not require a bridge rectifier. Only 2 diodes. Look it up.

[CORRECTION] For a dual supply you WOULD need 2 bridges.

Otherwise seems ok.