Figure 14 Simplified Schematic of BSR EQ-110X. This is a 10 band equalizer. The input goes to the noninverting input of OA1, an op amp. The output of OA1 connects directly to the inverting input making it a unity gain buffer. The output of OA1 goes through the parallel combination of a 3.6 k ohm resistor and a 150 pF capacitor to the noninverting input of OA2. The output of OA2 goes through the parallel combination of a 3.6 k ohm resistor and a 150 pF capacitor to its inverting input. The noninverting input of OA2 also connects to the bottom ends of all 10 slide pots. The inverting input of OA2 also goes to the top ends of all 10 slide pots.

The wiper of P1, Lowest frequency, goes through a 4.7 uf capacitor then a 0.047 uf capacitor to the noninverting input of OA3. The noninverting input of OA3 also goes through a 205.1 k ohm resistor to ground. The output of OA3 connects to its inverting input. The noninverting input of OA3 goes through a 582 ohm resistor to the junction of the two capacitors. The op amp, the two resistors, and the capacitor that is closest to the op amp constitute a gyrator which acts as an inductor. The 4.7 uf capacitor tunes the inductance of the gyrator to resonance at the center frequency of the band.

The wiper of P2, goes through a 2.2 uf capacitor then a 0.022 uf capacitor to the noninverting input of OA4. The noninverting input of OA4 also goes through a 259 k ohm resistor to ground. The output of OA4 connects to its inverting input. The noninverting input of OA4 goes through a 528 ohm resistor to the junction of the two capacitors.

The wiper of P3, goes through a 1.5 uf capacitor then a 0.012 uf capacitor to the noninverting input of OA5. The noninverting input of OA5 also goes through a 177 k ohm resistor to ground. The output of OA5 connects to its inverting input. The noninverting input of OA5 goes through a 510 ohm resistor to the junction of the two capacitors.

The wiper of P4, goes through a 0.68 uf capacitor then a 5.6 nF capacitor to the noninverting input of OA6. The noninverting input of OA6 also goes through a 222 k ohm resistor to ground. The output of OA6 connects to its inverting input. The noninverting input of OA6 goes through a 520 ohm resistor to the junction of the two capacitors.

The wiper of P5, goes through a 0.33 uf capacitor then a 2.7 nF capacitor to the noninverting input of OA7. The noninverting input of OA7 also goes through a 240 k ohm resistor to ground. The output of OA7 connects to its inverting input. The noninverting input of OA7 goes through a 470 ohm resistor to the junction of the two capacitors.

The wiper of P6, goes through a 0.177 uf capacitor then a 1.5 nF capacitor to the noninverting input of OA8. The noninverting input of OA8 also goes through a 183.3 k ohm resistor to ground. The output of OA8 connects to its inverting input. The noninverting input of OA8 goes through a 520 ohm resistor to the junction of the two capacitors.

The wiper of P7, goes through the series combination of a 430 ohm resistor, a 0.1 uf capacitor, and a 60 mH inductor to ground.

The wiper of P8, goes through the series combination of a 470 ohm resistor, a 0.039 uf capacitor, and a 41 mH inductor to ground.

The wiper of P9, goes through the series combination of a 560 ohm resistor, a 0.018 uf capacitor, and a 21 mH inductor to ground.

The wiper of P10, goes through the series combination of a 620 ohm resistor, an 8.2 nf capacitor, and a 12 mH inductor to ground.

End of verbal description.
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