Study the LM386based amplifier circuit handout used in the f

Study the LM386-based amplifier circuit handout used in the first homework. Then do the following (it may help to apply what you learned in problems 3, 4 above) a. Find the highpass comer frequency at the input due to C1. Assume the source is a microph th a Thevenin source resistance of 800 Ohms and the potentiometer VRI is set at the minimum-volume setting. b. What would this comer frequency become if the pot was at full volume? HINT: Recall that the input resistance of the amplifier is about 50K, and review your circuit analysis from HW1 c. Find the corner frequency at the ouput created by CA, assuming the speaker is 8 ohms and the amplifier is negligible (ie. 8 Ohms). Assume R1,C5 can be ignored. output resistance and the high-frequency rolloff. For the hi rolloff, you will need to look at the LM386 IC datasheet page 4) since the RC circuits that create it are in the internal circuits ofthe amplifier. Assume the amplifier mid-band gain is 26 dB at 1 kHz (the jumper JPI is \"open\" as in Hwij. e. From your Bode plot, estimate the overall low-frequency comer (3 dB poin) ofthe total amplifier circuit, and the \"bandwidth\" as defined by your book as f f f. you told to the comer of the overall amplifier to 30 Hz, what component should you change in the circuit and to what value? Over

Solution

VL = RL /(RL + R + 1/sC)* Vi

w = 1/c(Rs + RL)

w= 100 rad/sec

C = 0.638

Vi/Vs = 1/ infinity

0