Figure 4.2. This figure is almost identical to figure 4.1 except the three rectangles in the center are replaced by a standard symbol for an NPN transistor. A description of the symbol will be given at the end of this circuit description. On the left is a battery labeled V sub BB. Its negative end is connected to the common line. Its positive goes through a resistor labeled R sub B to the base of the transistor. The emitter of the transistor is connected to common. The collector goes through a resistor labeled R sub C to the positive end of a battery labeled V sub CC. The negative end of the battery is connected to common. The transistor symbol is enclosed in a circle. There is a vertical line inside the circle which is to the left of the center. The ends of this line do not touch the circle. A horizontal line goes to the left from the center of the vertical line. This horizontal line crosses the circle and is the base connection. Another line touches the vertical line about 1/3 of the way from the center to the top. This line angles up to the right to a point even with the top of the vertical line and as far to the right of the center of the circle as the vertical line is to the left. From this point the line goes straight up and crosses the circle. This is the collector connection. Another angled line starts on the vertical line about 1/3 of the way from the center to the bottom of the vertical line. This line angles down to a point even with the bottom of the vertical line and directly under the point where the upper angled line turns to exit the circle. The lower angled line turns straight down and crosses the circle. This is the emitter connection. There is an arrowhead on the lower angled line which is pointing down and to the right. The point is a little to the left of the point where the line turns straight down. If the transistor were a PNP type the arrowhead would point up and to the left. The point would be located a little to the right of where the angled line joins the vertical line. End verbal description.