25-02-2019, 07:03 PM
(25-02-2019, 04:44 PM)ppppenguin Wrote: I have this dim memory that model trains were happier with a rather rough DC than with the nice smooth output from a regulator. For example this H&M controller had a switch to give you halfwave rectification.
Or is this an obsolete idea. Or an urban myth.
The rough DC almost certainly was because that was what controllers had always supplied going back before solid state days - my first one used a copper oxide (might have been selenium) bridge rectifier. They were cheap and cheerful, so nobody bothered to make anything better.
The half wave rectification idea is not an urban myth - it gives better slow speed control for heavy freight trains, etc. However, the motors seem to chuck out a lot of noise - a more realistic way, I think, would be to smooth the DC and use PWM at a higher frequency.
The auto shutdown shown in step 3 of Alistair's link gives you the protection wanted without the need for fuses.
