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Application of the Equivalent Circuit in Measuring μ

Author: E.E. Kimberly

Fig, 27-15. Circuit for Measuring μ

The circuit shown in Fig. 27-15 may be used in measuring μ. The impedance Ze is the impedance of the coupling transformer as measured from terminals T1 and T2. The batteries do not appear in the equivalent circuit because only the incremental voltage is to be used and the battery resistances are negligible. The resistance Rp is the equivalent internal plate resistance of the triode. The voltage drop between cathode and grid is Vkg = - IR1 The voltage rise is


When Kirchhoffs Law is applied around the anode circuit, we obtain:


from which


If the values of R1 and R2 are so adjusted that Ip does not exist, there will be no signal at T1 and F2 and no signal voltage across Ze. The two loop circuits are then said to be balanced. When Ip = 0, μR1-R2 = 0 in Equation (27-17) and


Last Update: 2010-10-06