I have done serious work on the volt meter, I have really had problems getting a -5v supply out of a 9v battery. I tried using the replacement for the cd4009 as indicated in the data sheet from intersil, cd 4049 all to no avail. I actually wanetd to run the unit from a 9v battery for portability sake, now i have had to revert to the good old transformer and using an LM 317T and LM 7905 in conjuction wit 2 polar capacitors of differnt capacitances I have been able to get the 2 voltages (-5v and +5v) now my problem is calibration, am using a 1k instead of a 1.2k to get the 0-2000v scale,(That is the only scale am using) I shall find out 2 nite if it will work. :'(