Issue 324: EQ Questions

Review these four Test Your EQ problems that appeared in Circuit Cellar 324. Test your knowledge. Answers appear in issue 325.

Problem 1: In the following circuit, pick a value for Rx that sets the quiescent voltage at the collector to Vcc/2. The hFE (current transfer ratio) of the transistor is 100, and you can use the approximation that the internal emitter resistance re = 25 mV / Ic.

eq0690_fig1


Problem 2: What determines the low-frequency (high-pass) cutoff frequency of this circuit?


Problem 3: What is the high-pass cutoff frequency?


Problem 4: What is the best way to lower the cutoff frequency while at the same time reducing the loading on the signal source?