5 transistor gain block. Transistors Q1, Q2, Q3, and Q5 are all NPN, 2N3904. Q4 is a PNP, 2N3906. The input goes through a 1 microfarad capacitor to the base of Q1. The base also goes through a 100 k ohm resistor to ground. The emitter of Q1 connects to the emitter of Q2. The base of Q2 connects to one end of another 100 k ohm resistor. The base of Q2 also connects to one end of a 10 pf cap. The other ends of the 100 k and 10 pf connect to the output terminal. We will return to this point later. The base of Q2 also connects through a resistor, R5, see table, to the negative end of a capacitor, C2, see table. The positive end is grounded. The emitters of Q1 and Q2 connect to the collector of Q3. The base of Q3 connects through a 36 k ohm res to ground. The base of Q3 also connects through a 24 k ohm res to minus 9 volts. The emitter of Q3 connects through a 15 k ohm res to minus 9 volts. Q3 is a current sink and Q1 and Q2 form a differential pair. The collector of Q1 goes through another 15 k ohm res to plus 9 volts. The collector of Q2 goes directly to plus 9 volts. The emitter of Q4, the only PNP in the circuit, goes directly to plus 9 volts. The base of Q4 goes to the collector of Q1. The collector of Q4 goes to the output terminal. Remember that the 100 k ohm res and 10 pf cap connect here. The collector of Q5 also connects to the output terminal. The base of Q5 goes through a 3.3 k ohm res to ground. The base of Q5 also goes through a 1.5 k ohm res to minus 9 volts. The emitter of Q5 goes through a 1.0 k ohm res to minus 9 volts. Q5 forms a current sink and is the load for Q4. End verbal description.
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