The short video above shows how the pH amp functions without constant power. In this and the demonstration below, the probe has already been calibrated with buffers and the request is made to simply display the pH constantly--in this case the pH of the electrode storage solution (a buffer of approximately 7). Eventually the amp stabilizes and if left in this condition it's "functional". When doing a titration in which a graph of the ongoing process is built up on the calculator screen, it is necessary to send a pH value to the calculator for storage so that the corresponding volume at that point (entered on the calculator keypad) may be matched up with it. This operation causes the CBL to turn off the power to the probe. When the volume has been entered and the graph is updated, the power is turned on again and you must wait for stabilization again. Multiply that frustration by about 30 readings and couple it with the patience of a 10th grader (or frazzled teacher) and you can see the problem.|
In the short video below the only difference is that the probe has been supplied with constant power. The same amp and same electrode are being used. The effect is dramatic.
It may be that Vernier has since performed some magic on the newer pH amplifiers to minimize this problem. We are working with the original models that were available when the CBLs were first marketed.