Figure 7.1 Transformer Coupled Audio Amplifier. Plus 9 volts is at the top and ground is at the bottom. The hot input terminal goes to the negative end of a 1 u f capacitor. The positive end goes to the base of Q1, an N P N B J T. The cold input terminal is grounded. The base of Q1 also goes through a 20 k ohm resistor to ground. The base also goes through a 56 k ohm resistor to a point we will call Vcc2. The emitter of Q1 goes through the parallel combination of a 3.0 k ohm resistor and a 1 u f capacitor to ground. The collector goes to the top of the primary of an interstage audio transformer, 10k to 2 k CT. the bottom of the primary goes to Vcc2. It also goes through a 3.3 u f capacitor to ground. Vcc2 goes through a 1.8 k ohm resistor to plus 9 volts. The center tap of the interstage transformer goes through a 2.7 k ohm resistor to plus 9 volts. It also goes through the parallel combination of a 270 ohm resistor and a 10 u f capacitor to ground. The upper end of the secondary goes to the base of Q2. The lower end of the secondary goes to the base of Q3. The emitters of Q2 and Q3 are tied together and go to ground through the parallel combination of a 51 ohm resistor and a 33 u f capacitor. The collector of Q2 connects to the top end of the primary of an audio output transformer 500 ohm to 4 ohm. The collector of Q3 connects to the bottom end of the primary. The center tap goes to plus 9 volts. Minor details such as volume control and speaker are not shown but presumed to be present. End verbal description.
Go back.