Hi,

I did not forget to put the sq brackets this time, Bob . :-)

Not a query, but tripped on this one, wondered for a while, later on
alone realization dawned.
Thought about sharing this one on the list.

Have a 230V/12-0-12 CT transformer, of which 0 &12 connected to a
Bridge rectifier, the output of which is smoothed out by a 680uF/200V
capacitor, providing about 16VDC (12 x 1.4142). The power supply
worked well and good enough.

The transformer was left connected to the mains for a while, in absent
minded mode of operation. A few days later, just before wanting to
test a small board measured the voltage on the power supply, saw it
was about 80V.

Sat in thoughts for about an hour what was wrong, thought maybe the
transformer windings had sprung a leak. Thought about it for a moment,
then thought probably the capacitor was getting charged due to no
load.

Discharged the capacitor with a huge spark. Things pretty much settled down=
..

At least thoughts burned up a few hours, where that 80Vdc was coming from.
After that, sat back and laughed at myself.

Cheers,
Manu
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.