Regarding the overvoltage: it is a danger few people seem to realise, until of course it is too late.
I am setting up my own (as per usual), basically using a cheapo LM2596 module from the far East. It can handle a wide range of input voltages, will produce 3 amps which should be ample, and can be adjusted. This last point is apparently relevant because certain devices take up so much current that one needs to offer 5,1 or even 5,2 V= at the other end of the charge cable.
But most importantly, I will definitely add an over-voltage protection, in the form of a crowbar circuit. There will be a fuse in the 5V= supply line, and downstream of that a thyristor to shortcircuit the output in case of overvoltage, thus blowing the fuse. That requires fast detection and a fast thyristor, I intend to use a little schematic by dear old Mr. Jim Weir.
PS back to the original issue of radio interference: yes, one should take care, inserting some inductors and (ceramic) bypass-capacitors in any application of a switching power supply. But I can't help having my doubts about the quality of the radio that - on one particular frequency! - was so upset with the switcher's noise. What make/model was it?
Last edited by Jan Olieslagers; 8th May 2016 at 10:52.