1008 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1952 



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Fig. 7 — Interior view of the general -purpose bridge. The panel edge shown in 

 the foreground is the left edge of the bridge shown in Fig. 6. 



FIVE-MEGACYCLE MAXWELL INDUCTANCE BRIDGE 



To facilitate the measurement of low-valued inductors, there was need 

 for a direct-reading inductance bridge inasmuch as such measurements 

 entail considerable computation effort when using the general-purpose 

 bridge. Accordingly, it was decided to build a five-megacycle Maxwell 

 inductance bridge to cover a range from 0.001 microhenry up to 10 micro- 

 henries, and effective resistance values up to 11 ohms. The basic circuit 

 is the same as the Maxwell bridge in Fig. 1, but the design embraces 

 such refinements as glass-sealed deposited-carbon resistors for the con- 

 ductance standard, and a worm-driven center-fed variable air capacitor. 

 Special woven-wire resistors on spools of Teflon are used for the tw^o fixed 

 arms, and are compensated to give a constant product of practically zero 



