Making Waves Power supplies.

I was sat wondering what I should propose as a winter project this year – after all we all know how these winter months can drag on with long nights and cold wet days – and looking through some old notes I have decided on building myself a new PSU.  We all know the importance of having a good PSU in the shack, whether it be a switched mode type or linear regulated type, to power our radios and various peripherals.  I personally don’t like the switched mode ones so very much as they do tend to be rather noisy in the HF spectrum where most of my activity occurs.

So a standard linear regulated power supply it will be then.  Surprisingly very few components are needed for this although a good metal case with ventilation will be a must.  Let’s look at a layout plan.

Rectified_PSU_transformerfig.1

In its simplest form A is a fuse unit for the input to prevent any mains surge from damaging the transformer, B is a double wound transformer to convert 240V to 12V (still AC), C is a full bridge rectifier and D is a smoothing capacitor.  The output is then 12V DC.

With the above assembly we should expect to see the following outputs when measured on an oscilloscope:

AC_Sinewave fig.2 AC sinewave.

The AC sinewave should be seen at the output terminals of the transformer.

Rectified_Waveform fig.3 rectified AC

Tis is what we should expect to see at the output terminals of the full wave bridge rectifier.

Regulated_DC_Output  fig.4 Regulated DC output

And this is what we would expect to see across the output terminals all being well.

Obviously, the size of the transformer depends on how much current you wish to draw and an inline fuse between the unit and the equipment you will be powering will also be necessary in case of any surges (or faults with the equipment).  I shall now attempt to source components and will report back later with progress.

 

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