- Published in issue 2/1997 on page 36
Battery-operated AF pre-amplifier - part 2
Following the detailed description of the preamplifier in last month's installment, this second and final part of the article deals with the power supply and the construction of the complete unit. More so than usual, the power supply forms an important part of the overall design. It consists of 12 NiMH batteries, size AA (RG/HP7) with a nominal capacity of 1.2 Ah, and a moderately fast charger that takes about three hours to fully charge a set of flat batteries (note that it is not a good idea to discharge these batteries completely - the nominal voltage level is maintained at 1.2 V during 80% of the discharge cycle).