Computerscope (2)

COMPUTER- SCOPE-2 i,..tvvmmos SONgANN UMS • by R v Linden IMAMU"il. 1:••H;V,.C1•ANIIIAIIWIWIN After last monthS detailed look at the layout and circuit of the drive unit, this second part deals with the construction, calibration, and necessary software. The printed-circuit board (No. 86083- Fig. 5) needs to be completed with perhaps more care and attention than usual for two reasons. Firstly, the clock in the RAM and the A-D- converter operates at a fairly high frequency, so that neat soldering is a must. Secondly, the attenuator sec- tion should be constructed and screened neatly, since this deter mines to a large degree the overall accuracy of the circuit. Fig. 5 shows the component layout of the PCB: since the board is double- sided with through-plated holes (see also p. 83 of last month"s issue), it is advisable to check all such holes with a multimeter before any work is done; if the through-plating of a hole is not sound, it is a difficult job to locate this after th...