Figure 7.6. On the left the lower input terminal is grounded. The upper input terminal goes through R1, 100 k ohms, to the inverting input of o eh 1. The noninverting input goes through a 51 k ohm resistor, R3, to ground. There is a voltage divider consisting of R6, 18 k ohm and R8, 5.6 k ohm from plus 9 volts to ground. The 5.6 k is the one connected to ground. There is a similar voltage divider consisting of R7, 18 k and R9, 5.6 k from minus 9 volts to ground. A 1 k ohm pot has its left end connected to the junction of R6 and R8, and its right end connected to the junction of R7 and R9. The wiper of the pot goes through R4, 3 meg ohm to the inverting input of O eh 1. The output of o eh 1 goes through R2, 100 k ohms to the inverting input. The output of o eh 1 goes through R10, an 11 k ohm, to the inverting input of O eh 2. The noninverting input is grounded. The output of o eh 2 goes through a 3300 pf cap to the inverting input. The output also goes to the emitter of Q1, a PNP transistor. The base of Q1 is grounded and the collector goes to the inverting input of O eh 2. The output of o eh 2 goes to the emitter of Q2, identical to Q1. The collector and base of Q2 are died together and go through R11, 30 k ohm to minus 9 volts. The collector and base of Q2 also go through R12, 47 k ohm, R13, 50 k ohm pot connected as a rheostat, and R14, 2.2 k ohm to ground. The junction of R13 and R14 goes to the upper output terminal. The lower output terminal is grounded. End verbal description.
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