A handy nomograph is one relating decibels to voltage or power ratio. The three variables are input, output and decibels.

Amplifiers are rated according to the number of watts output they can handle without distortion.

In the reproduction of any record we must take into account the various recording characteristics and compensate the pickup accordingly.

The human ear responds differently to sounds of different frequencies and intensities, and attempts to compensate for losses in high-and low-frequency gain which are common in most types of audio amplifiers.

Push-pull stages are often used in a speech amplifier either to supply the necessary voltage to drive an output stage or to reduce certain types of distortion.

The degree to which the falling off at low frequencies takes place in a resistance-coupled amplifier may be seen by feeding a voltage of fixed amplitude but varying frequency through the coupling condenser.

Let us attempt to throw some light on the theory behind the operation of the lowly speech amplifier found in so many types of electronic equipment: radios, electric phonographs, public address apparatus, electronic pianos and sound-on-film projectors.

This chapter deals with the operation and circuitry of transistor oscillators. In general, these fall into two categories: the feedback (or vacuum tube equivalent) types, and the negative-resistance (or current multiplying) type.

This chapter deals with the design and operation of the transistor as a low-frequency amplifying device based on the transistor characteristics and limitations discussed in the preceding chapters.

This article contains important miscellaneous considerations, including transistor operation at high frequencies, i-f and r-f amplifiers, limiters, mixers, handling techniques, hybrid parameters, and printed circuits.