Self Balancing Skin Conductance Amplifier SC4 measures directly in conductance, using DC coupling with constant voltage electrode excitation. With such DC measurement base-line suppression is necessary.
Conventional units use a manual potentiometer which has to be set periodically by the operator.
This way, very high sensitivity may be used without risk of signal blocking. This entirely solves the problem of large SCRs which go off scale with conventional apparatus. SC4 was originally designed in 1979 to comply with specifications given by Lykken and Venables. The SCR is the most useful aspect of the skin conductance measure, as it directly relates to level of arousal in the subject. This ensures low noise with complete safety and individual isolation of electrode connections to prevent interaction with other amplifiers.