Question

3-15. In a certain experiment, the collector current of a transistor was measured at different values of collector-emitter volt- age, while the base current was held con- stant. The results of the experiment are summarized in the following table: IC Ig = 100 PA VCE 15 mA 10 V 16 mA 17 mA 20 V 18 mA 5V 15 V 13 = 200 A VCE 5 V 10 V 15 V 20 V 30 mA 32 mA 34 mA 36 mA 1s = 300 PA Valc 5V 45 mA 10 V 48 mA 15 V 51 mA 20 V 54 mA Plot the experimental data and graphi cally determine approximate values for the following: (a) B at VCE = 8 V and Ig = 100 A, (b) B at VCE = 14 V and Is = 250 A, and (c) the Early voltage.

Answer 1

10/10/2014 Plotting the experimental data, Ans: a) for I data set a IR IA IB - 100 UA 2004A 200-A VCE Nice IC Ic IC 5Y ISMA 5V 30 A lov 16 mA lov 32mA 34MA Vice 5045 MA lov 48mA Is 51 mA dov 54mA Isy MA 157 20v 18 MA 20V 3674 Output characteristics curve for above data set will be IB = 3004A of Is=800HA IB - LOOJA 0 9 4 6 8 10 12 14 16 18 20 Vee CV b) Determining approximate values for the following; and Ige 1004A . ;) B at VCE = 8v We know that, Ice Ac is approximately B = at VCE = 8M 15.6 NA 15.6 MA 100 JA B- 156

b) B at VCE = 14V and IB = LOMA 250 MA. at IB = 250 mAh VCE and Ic values equal to; approximately will be I VCE 57 lov ISV 200 Ic . 37.5 MB 40mA 42-5MA 45 MA So we know that; IBE Ice Ic at UCE = 100 value of will be; IB Ice 42mA So 42 mA 250 MA. 168 Early voltage : Early valtage is calculated by plotting back the curves Coutput characteristics and see if they intercepta; This interception happens at - 48 so; The early voltage is; This value is calculated by applying following to the output characteristics curre concept

Early -VA= voltage AVCE like the above diagram of we extend the IB values to plot the curre back, then we get -VA so this concept I have applied to the output characteri stics aurive to get the value of early voltage.