Figure 7.3 Transformer less Amplifier from the 1960s. One side of the input is grounded. The other side goes through a 10 microfarad capacitor then a 10 k ohm resistor to the base of Q1. We will return to this point two more times. The emitter of Q1 is grounded. The collector goes through a 33 k ohm resistor to plus 27 volts. The collector also goes to ground through a 270 pf capacitor. The collector also goes to the base of Q2. The emitter goes through a 330 ohm than a 1.8 k ohm resistor to ground. There is a 250 microfarad capacitor in parallel with the 1.8 k ohm. The junction of the 330 ohm and 1.8 k ohm goes to one end of a 270 k ohm resistor. The other end of this resistor goes to the base of Q1. The base also goes through a 33 k ohm resistor to ground. The collector of Q2 goes through a 3.3 k ohm resistor to plus 27 volts. The collector also goes through a 250 microfarad capacitor then a 1 k ohm resistor to the base of Q3. The base also goes through a 2.2 k ohm resistor to ground. The base also goes through a 33 k ohm resistor to a point will call the amplifier midpoint. The emitter goes through a 270 ohm resistor to ground. The collector goes through a 330 pf capacitor to ground. The collector also goes to the base of Q4, a PNP. Note, this is the only PNP transistor in the circuit. All others are NPN. The collector also goes through 3 diodes all in series, then through a 4.7 k ohm then a 1 k ohm resistor to plus 85 volts. There is a 50 microfarad cap connected from the amplifier mid point to the junction of the 1 k and 4.7 k ohm resistors. The junction of the 4.7 k ohm resistor and the anode of the upper diode goes to the base of Q5. The collector goes to plus 85 volts. The emitter goes through a 100 ohm resistor to the amplifier mid point. The emitter also goes to the base of Q7. The collector of Q4 goes through a 100 ohm resistor to ground. The collector also goes to the base of Q6. The emitter of Q4 goes through a 4.7 ohm resistor to the collector of Q6. The collector of Q7 goes to plus 85 volts. The emitter goes through a 0.67 ohm 5 watt resistor to the amplifier mid point. The amplifier mid point goes through another 0.67 ohm 5 watt resistor to the collector of Q6. The emitter goes to ground. The amplifier mid point goes to one end of a 2.2 microfarad capacitor. The other end of this capacitor goes through the parallel combination of a 330 k ohm resistor and a 2.7 pf capacitor to the base of Q1. The amplifier mid point goes to the positive end of a 4000 microfarad capacitor. The other end goes through am 8.8 microhenry coil to the hot speaker output. The amplifier mid point goes through a 0.001 microfarad capacitor to the hot speaker output. The hot speaker output goes through a 0.1 microfarad capacitor then an 11 ohm 5 watt resistor to ground. The cold speaker output goes to ground. End verbal description.
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