Question

The circuit shown in Figure Q4-1 includes an audio source and the equivalent circuit of a loudspeaker that you have been asked to analyse. 4. a) Assuming the speaker is to operate at a single frequency of 200 Hz and is5 driven by a cosinusoidal signal with peak amplitude of 20 V; determine the equivalent impedance of the speaker When connected to the audio source, calculate the current flow i() When testing the loudspeaker detailed in Q4a) i), you can hear some low- 4 frequency 'mains hum' noise that is very unpleasant and annoying. To remove this low frequency noise you decide a filter is required. Draw the idealised frequency response of a low pass, high pass and notch filter Which of these filters is best suited to remove the mains hunm interference? You have decided to design and build a filter to remove the interference. 4 Sketch a suitable circuit diagram, using an inductor and resistor, for the filter described in Q4a) iii). You are provided with a 100 Ω resistor and have a selection of inductors available: 500 μH, 40 mH, 80 mH, 160 mH, and 500 mH. Design a filter which will give a cut-off frequency, fe, as close as possible to 200 Hz. Where would the filter be inserted in the circuit shown in Figure Q4-1 to remove the mains hum? iii)w Audio Source Loudspeaker 1 mH it) 82 8Ω Voice Coil Voice Coil Resistance Inductance v(t) 100μ F Cone Mass Cone Suspension Figure 04-1

Answer 1

I am solving section b)

i) resonance circuits find application in resonance tuning amps.

Parrallel resonance circuits may be used as current amplifr.

Series resonance circuits often can rendered as voltage amplifiers.

iii)Please refer to fig.

ii) please refer to figure