|  | H |
SECTION H — ELECTRICITY

|  | H03 |
BASIC ELECTRONIC CIRCUITRY

|  | H03B |
GENERATION OF OSCILLATIONS (measuring, testing Fulltext... Hierarchy... Expanded...G01R; generators adapted for electrophonic musical instruments Fulltext... Hierarchy... Expanded...G10H; masers, lasers Fulltext... Hierarchy... Expanded...H01S; dynamo-electric machines Fulltext... Hierarchy... Expanded...H02K; power inverter circuits Fulltext... Hierarchy... Expanded...H02M; details applicable both to generators of sinusoidal oscillations and to generators of non-sinusoidal oscillations Fulltext... Hierarchy... Expanded...H03K; generations of substantially non-sinusoidal oscillations Fulltext... Hierarchy... Expanded...H03K; generations of sinusoidal or non-sinusoidal oscillations at will Fulltext... Hierarchy... Expanded...H03K; generation of oscillations in plasma Fulltext... Hierarchy... Expanded...H05H)

|  | H03B |
Note(s) This sub-class deals with (a) generation of substantially sinusoidal oscillations directly or by frequency-changing, (b) regulation of generator output, (c) synchronisation of generator output and (d) generation of noise currents or voltages.

|  | H03C |
MODULATION (measuring, testing Fulltext... Hierarchy... Expanded...G01R; masers, lasers Fulltext... Hierarchy... Expanded...H01S; modulators specially adapted for use in dc amplifiers Fulltext... Hierarchy... Expanded...H03F 3/38; modulating pulses Fulltext... Hierarchy... Expanded...H03K 7/00; pulse code modulation Fulltext... Hierarchy... Expanded...H03K 13/00; so-called modulators capable only of switching between predetermined states of amplitude, frequency or phase Fulltext... Hierarchy... Expanded...H03K 17/00, Fulltext... Hierarchy... Expanded...H04L; synchronous modulators specially adapted for colour television Fulltext... Hierarchy... Expanded...H04N 9/50)

|  | H03C |
Note(s) This sub-class deals only with modulation, keying, or interruption of sinusoidal oscillations or electromagnetic waves, the modulating signal having any desired waveform. In this sub-class, circuits usable both as modulator and demodulator are classified in the group dealing with the type of modulator involved.

|  | H03D |
DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER (masers, lasers Fulltext... Hierarchy... Expanded...H01S; circuits capable of acting both as modulator and demodulator Fulltext... Hierarchy... Expanded...H03C; details applicable to both modulators and frequency-changers Fulltext... Hierarchy... Expanded...H03C; demodulating pulses Fulltext... Hierarchy... Expanded...H03K 9/00; transforming types of pulse modulations Fulltext... Hierarchy... Expanded...H03K 11/00; pulse code modulation Fulltext... Hierarchy... Expanded...H03K 13/00; repeater stations Fulltext... Hierarchy... Expanded...H04B 7/14; demodulators adapted for telegraphic ac systems Fulltext... Hierarchy... Expanded...H04L 27/00; synchronous demodulators adapted for colour television Fulltext... Hierarchy... Expanded...H04N 9/50)

|  | H03D |
Note(s) This sub-class deals only with (a) demodulation or transference of signals modulated on a sinusoidal carrier or on electromagnetic waves, and (b) comparing phase or frequency of two mutually-independent oscillations.

|  | H03F |
AMPLIFIERS (measuring, testing Fulltext... Hierarchy... Expanded...G01R; optical parametric amplifiers Fulltext... Hierarchy... Expanded...G02F; circuit arrangements with secondary emission tubes Fulltext... Hierarchy... Expanded...H01J 43/30; masers, lasers Fulltext... Hierarchy... Expanded...H01S; emergency protective circuit arrangements for amplifiers, e.g. by switching off or by automatic replacement of tube, Fulltext... Hierarchy... Expanded...H02H 7/20; control of amplification Fulltext... Hierarchy... Expanded...H03G; coupling arrangements independent of the nature of the amplifier Fulltext... Hierarchy... Expanded...H03H; amplifiers capable only of dealing with pulses Fulltext... Hierarchy... Expanded...H03K; repeater circuits in transmission lines Fulltext... Hierarchy... Expanded...H04B 3/36, Fulltext... Hierarchy... Expanded...H04B 3/58; application of speech amplifiers in telephonic communication Fulltext... Hierarchy... Expanded...H04M 1/60, Fulltext... Hierarchy... Expanded...H04M 3/40)

|  | H03F |
Note(s) This sub-class deals with (a) linear amplification, there being linear relationship between the amplitudes of input and output, and the output having substantially the same waveform as the input, (b) dielectric amplifiers, magnetic amplifiers, and parametric amplifiers when used as oscillators or frequency-changers, and (c) constructions of active elements of dielectric amplifiers and parametric amplifiers for which no provision exists elsewhere.

|  | H03G |
CONTROL OF AMPLIFICATION (control of transmission in lines Fulltext... Hierarchy... Expanded...H04B 3/04)

|  | H03G |
Note(s) This sub-class deals with (a) control of gain of amplifiers or frequency-changers, (b) control of frequency range of amplifiers, and (c) limiting amplitude or rate of change of amplitude.

|  | H03H |
IMPEDANCE NETWORKS; RESONANT CIRCUITS; RESONATORS (measuring, testing Fulltext... Hierarchy... Expanded...G01R; impedance networks or resonators comprising distributed impedance elements only i.e. of the waveguide type, Fulltext... Hierarchy... Expanded...H01P; networks specially designed for coupling between the active elements in an amplifier, e.g. wide-band coupling networks, Fulltext... Hierarchy... Expanded...H03F; networks for modifying the frequency characteristics of communication cables, e.g. equalising networks, Fulltext... Hierarchy... Expanded...H04B 3/14)

|  | H03H |
Note(s) This sub-class deals with (a) networks comprising lumped impedance elements, (b) networks comprising distributed impedance elements together with lumped impedance elements, (c) networks comprising electromechanical or electro-acoustic devices, (d) networks simulating reactances and comprising discharge tubes or semiconductor devices, and (e) constructions of electromechanical resonators.

|  | H03J |
TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS (indicating arrangements for measuring Fulltext... Hierarchy... Expanded...G01D; measuring, testing Fulltext... Hierarchy... Expanded...G01R; remote-control in general Fulltext... Hierarchy... Expanded...G05, Fulltext... Hierarchy... Expanded...G08; control of generators Fulltext... Hierarchy... Expanded...H03B)

|  | H03K |
PULSE TECHNIQUE (measuring pulse characteristics Fulltext... Hierarchy... Expanded...G01R; mechanical counters having an electrical input Fulltext... Hierarchy... Expanded...G06M; storage devices Fulltext... Hierarchy... Expanded...G11; construction of switches involving contact making and breaking for generation of pulses, e.g. by using a moving magnet, Fulltext... Hierarchy... Expanded...H01H; generators of substantially sinusoidal oscillations Fulltext... Hierarchy... Expanded...H03B; modulating sinusoidal oscillations with pulses Fulltext... Hierarchy... Expanded...H03C; Fulltext... Hierarchy... Expanded...H04L; discriminator circuits involving pulse counting Fulltext... Hierarchy... Expanded...H03D)

|  | H03K |
Note(s) This sub-class deals with (a) methods, circuits, devices, or apparatus for generating, counting, amplifying, shaping, modulating, demodulating, coding, decoding, or otherwise manipulating substantially non-sinusoidal oscillations, i.e. electric pulses, (b) electronic switching not involving contact-making and breaking, and (c) logic circuits handling electric pulses. In this sub-class, an "active element" is understood to exercise control over the conversion of input energy into an oscillation or a discontinuous flow of energy.