[analog97]

Still trying to improve my circuit reading skills.  It looks like the loading switch turns on BOTH the battery pack and the wall wart jack.  So, I am guessing you need to take out the batteries before you plug in the wall wart?  OR, do you need to decide how you want to power it....then just do one or the other?    Thanks in advance.  I have received the PCB, but a part is back-ordered from Digi-Key (again) so I am just being careful in preparation, so as to make my Hagtech succesful build score 7/7.

[hagtech]

The gain switch doubles as an on/off switch (separate throw).  The diode in series with the regulator prevents battery discharge.  And there is a switch on the dc jack that disconnects batteries when the wall wart is plugged in.  So ok to leave batteries installed.

jh

[analog97]

Excellent engineering!!  Thanks.....looking forward to 7/7.