The excess of one direct capacity C12 over another C55 is readily determines by connecting terminals 1 and 5 to corner D, terminals 3, 4, 7, 8, . . . to corner C or A, and then balance with terminals 2 and 6 on A and C, respectively, and repeat, with their connections reversed.
Potentiometer Method, Fig. 3
The required direct capacity C12 is balanced against one of its associated direct capacities, augmented by a standard direct capacity
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Fig. 3—Potentiometer Method for Direct Capacity
C1, and the measurement is repeated with the required direct capacity and standard interchanged. Let R′, R″ be the resistance required in arm A B of the bridge for the first and second balance, then, S being the total slide wire resistane and G1 the grounded capacity of terminal 1:[1]
This ratio method requires for the bridge a variable or slide wire resistance and a constant condenser, and it may be employed as an improvised bridge, when sufficient variable capacity is not available for the Colpitts method. Not being a substitution method, however,
- ↑ See appendix, section 3.
