Test No. 106 - "Comparison of Readings of Self-Potential at Constant Temperature"
(Electrolytic Capacitors EL-10 & EL-11)

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May 24 to June 13, 1977
Stewart Ct. Laboratory
Sunnyvale, CA

Copyrighted © by The Townsend Brown family. All rights reserved.


a) To compare (over a period of 20 days) the self-potential output of two dissimilar electrolytic capacitors under constant conditions.

b) To check the appearance and disappearance of diurnal cycles or other recurring fluctuations.


Two independent systems were used so as to avoid any possibility of inter-effects.

1) EL-10 (Mallory 240,000 ufd 7.5V DC)
Const-temp. ethylene glycol bath 30oC +/- .1oC
Austin stripchart recorder No. 2.

2) EL-11 (GE 90,000 ufd 10V DC)
Const-temp. air cabinet 38oC +/- 1.0oC
Austin stripchart recorder No. 3.


Actual recorder charts are shown, reduced in size and adjusted for time concurrence.

It is observed that, during the period from May 24 to 28, diurnal cycles of the two sensors bore a reciprocal relation, but during the period that followed, May 29 to June 13, the relation appeared approximately direct. In most cases the phasing was strikingly concurrent.

Graphic - Figure 1


This series of comparative tests appears to indicate that a common (external) parameter affects both (dissimilar) capacitors but that individual variations and departures do exist.

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