酸鹼計電路

http://damien.douxchamps.net/elec/ph_meter/
http://pe2bz.philpem.me.uk/Comm01/-%20TestEquip/-%20PH-Meter/Ph-007-PhMeter/ph.htm
http://www.ph-meter.info/pH-meter-construction

https://code.google.com/p/phduino/

Key word: ph amplifier circuit