Audio in Electronics

Audio in Electronics

1. Properties

   • The human ear can detect audio signals ranging from, 200Hz to 20kHz
   • Human voice
     • Pitch
       • indicates the frequency of the sound
       • Loudness
         • indicates the amplitude of the sound wave
         • Tone
           • Describes the quality of the sound

2. Filters

   • These allow some signal frequencies to pass through while blocking others
   • Ideal
     • High Pass Filter (HPF)
       • Band Filter (BPF)
         • Low-Pass filter (LPF)
           • This filter only allows low frequency signals to pass throuhg unaffecte, but blocks out high frequency signals
         • This filter only allows a certain range or 'band' of frequencies to pass through
       • This filter only allows high frequency signals to pass though unaffected, and blocks out low frequencies
   • Real
     • Passive
       • These are made from combinations of resistors, capacitors, and inductors. They can suppress certain frequencies within a spectrum and have a gain of 1
     • Active
       • These also amplify certain frequencies

3. Capacitors

   • In DC circuits, these act as a break in the circuit, preventing the flow of continuous current
   • In AC circuits, however, their behaviour seems different. They limit the current flow similarly to how resistors do in a DC circuit
   • Symbols
     • Xc
       • f
         • C
           • Z
             • Vout
               • Vin
                 • Input voltage (volts)
               • Output voltage (volts)
             • Impedance (Ohms)
           • Capacitance (Farads)
         • frequency of AC signal (Hz)
       • Reactance (Ohms)