DJanGo wrote: > remember most of these "cheap" devices doesnt have a Transformer > Protector Diode like a laboratory power supply. > Only this diode will stop the current to go back. > > Anyway The only thing that solves his proble is dismantle the PSU, check > everything or buy a new one. > There are too many may and be s what really happend.
Every DC supply regardless of cost has such transformer protector diode already built-in. It is called the rectifier bridge. And in a DC supply, there is nowhere for the rectified current to backfeed to, as it is a transformer-coupled topology. Perhaps you are confusing such a mystery diode with an inrush current thermistor, which are more common on better supplies with heavier filter loads. The primary difference between a $5 wallwart and a $500 precision supply are the quality, quantity and values of the core parts. Big toroidal core windings, exotic diode types, and banks of first-tier filter electrolytics are not cheap. All the rest are variations of the same old three step: voltage stepping, rectification, and filtering. Back to the OT: powering a SB3 or Touch is childs play. All they need is a 5vdc output at 2A or better. Nothing too fancy, and even a higher current USB charger could probably handle the job. They do sound a little better on a quieter supply, in my experience. ------------------------------------------------------------------------ sgmlaw's Profile: http://forums.slimdevices.com/member.php?userid=13995 View this thread: http://forums.slimdevices.com/showthread.php?t=109831
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