I have done enuff research to confirm that it works the way it is in the schematic. I have carried it out and the DVM worked to an accuracy of 98%. Don't worry it will work. ;)
This is about the power source using the 1K resistors, I used the LM 317T for positive voltage because I found out the 7805 refused to work with the 7905, this I have tested over and over again beforew comin to that conclusion. A positive voltage enters the 317T and is varied until +5V is at...
Having gone through the circuits, datasheets, replacement guides (ECG master replacement guide from Philips) and after the alarm about the inconsistencies I came out with these corrections and I believe they are correct as far as am concerned. Also I have included a modified circuit diagram for...
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...