29 Jan
2009
29 Jan
'09
12:11 p.m.
On 29 Jan 2009 at 19:49, Tony Duell wrote:
Beware of the last fault. Some SMPSUs don't have
bleeder resistors on the
mains smoothing capacitor, relying on the chopper circuit to discharge
them. If this isn't running for any reason, the capacitor stays charged
and will zap you. Now how do you think UI found that out :-)
Although the basic principle is simple, SMPSU design to me is still a
black art and it seems that the practitioners of it are all older
than 50. One of the better websites on the subject is:
http://www.smpstech.com/index.htm
FWIW,
Chuck