[sdiy] transformer question

[Tony Allgood]

>When capacitors get charged to full working voltage, a relay shorts
those 1k resistors and connects the load to the power supply.

This is done on some commercial large scale linear units, also on very
big SMPS systems. One of the interesting things about this particular
type of design is making sure the relays are reset fast enough on power
down or during brown outs. If they haven't flipped off in time before
power is re-applied, the initial inrush can be fatal to the power
supply.

Other supplies use PTC thermistors to acheive the same goal. Cheaper and
easier but will fail eventually... like everything I suppose :-)

Rather glad I don't have to design these sort of things nowadays!

Regards,

Tony Allgood, Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.oakleysound.com/projects.htm
My music: www.mp3.com/taklamakan