g2. Surplus Power Supply Notes (PSU)


LME BMN903231/2 -28V 50W regulator using swinging choke regulator. It is supposed to be a "-24V supply", but "-24V" for
telecommunication equipment usually means -27...28V.
It is very easy to build a shuntregulator (2N3055 and zenerdiode) to set a maximum voltage level. 30V was chosen for Storno CQP612
The regulator voltage is set as high as possible for minimum regulator standing power, and the transformer is tapped for practical level of
output voltage. Since I use a MC7924 regulator, it must have some voltage over the regulator, and the voltage from the psu should not drop below
-26V for -24V steady from the MC7924 regulator. (2003.07.09)

LME BMN903231/2 component locations. (2003.07.09)

An unmodified LME (EB) BMN903231/2
The only problem with such swinging choke type power supplies is the weight, the choke weight almost the same as the transformer,
so this unit weights 6.4kg. But the great advantage is that it has always softstart. It very well suited in areas where mains supply is
instable or it is mains noise peaks from lightenings.

LME BMN903331/2, -24V 130W supply, weight 12.9kg. The circuit is very similar to the first version

It is also a +200V supply