- Pin 2 3 5mm Stereo Socket P Pwr 3 2 I Header 3 Gnd Ci 0 Vdd C8 0 C6 0 07 0 C9 Vss 0 1 Gnd R3 Www 0 Ri 0 Ww C3 0 Gnd G 1 (60.43 KiB) Viewed 15 times
- Pin 2 3 5mm Stereo Socket P Pwr 3 2 I Header 3 Gnd Ci 0 Vdd C8 0 C6 0 07 0 C9 Vss 0 1 Gnd R3 Www 0 Ri 0 Ww C3 0 Gnd G 2 (88.13 KiB) Viewed 15 times
Your tone control circuit must satisfy the following specifications: 1. peak input signal voltage of 8 V; 2. peak output signal voltage of 8 V; 3. operating frequency range of 20 Hz - 20 kHz (audio band); 4. three tone bands with cut-off frequencies at 140 Hz and 1.28 kHz (± 10%); 5. variable gain control (± 6 dB) for each band; 6. input impedance of at least 10 kn; 7. output impedance of at most 1 k.
1. Determine the minimum input impedance of each stage. This will be the lower limit for your resistor values (especially applicable to the complex input impedance of the high-pass filter). 2. Determine the input impedance of the op-amps. We want our resistors to be much lower than the input impedance, so ideally choose the upper limit of the resistors to be 100 times smaller. You are recommended to check up the op-amps' input impedances from the datasheet, available on MyUni. However, it is possible that we might not meet the upper limit due to Step 1, and need to relax this limit. Discuss how this can affect your design. 3. Determine the input coupling capacitor C₁. Hint: the lowest pass frequency is 20 Hz. 4. Calculate the components for low-pass filter: R1, R2, C2. 5. Calculate the components for high-pass: R3, R4, C3. 6. Determine the components for mid-band summing amp: R5 - Rg. 7. Determine the components for variable gain summing amp: R9 R12. Rv1 - Rv3 are 20 k potentiometers.
8. Calculate the required capacitor for the final low-pass filter: C4. What criterion will you use in choosing this value? Hint: the highest pass frequency is 20 kHz.