It is only a simple psu, but using a 24VAC transformer
[http://home.online.no/~la8ak/images/4ua3.gif)

Wonder what size capacitors I should use to keep ripple minimum above
+24V?
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As a rule of thumb not less than 2000 microFarad per ampere
Hence for a 20 Amperes supply a total of 40KmicroFarad or more.

Frank GM0CSZ / KN6WH