تيار الصمام الثنائي -تقويم الموجة الكاملة -الصمامات ذات المهبط المسخن .. الإلكترونيات

Diode Current - Full Wave Rectification -
Heated Cathode Diodes .. Electronics

Diode Current

If the diode anode is connected via a variable resistor (81) and a milliampere meter is connected in the anode circuit to measure the current, we notice that the intensity of the anode current increases as its voltage increases, due to the increase in the number of electrons attracted to it. The increase in the intensity of the current continues until the anode voltage reaches a certain value, after which the intensity of the current becomes constant and does not change regardless of the increase in the voltage value. The anode current in this case is called the saturation current.

The diode is used in half-wave rectification circuits to allow only half a wave of alternating current waves to pass, thus obtaining a direct current pulsed with a half-rectification. It is possible to obtain a direct current with a full wave using a double diode, or using two (83) diodes together. In this case, a transformer with a secondary coil with an intermediate point is used. The secondary coil of the transformer is connected so that one of the two leads is the negative half-wave.

81 - Current flow in the diode.

82 - Full-wave rectification.

Most AC power supplies include a rectifier that supplies the valves with a pulse-free DC current in addition to being constant. Therefore, the current resulting from the full-wave rectifier passes through a leveling circuit that usually consists of leveling capacitors and choke coils (83). The coils work to impede the change in current intensity due to their high self-inductance, while the capacitors store the charge when the voltage rises and dissipates it when it falls, thus obtaining a smooth, even current that is completely similar to the battery current.

Using diodes

Large thermoelectric diodes (84) are used as power rectifiers in which we can obtain a high-intensity DC current and high voltage. Small diodes are used in detection and adjustment circuits and in rectifying the signals required in automatic loudness control bias circuits. In indirectly heated diodes, the heating filament is connected to a different circuit from the one to which the cathode is connected. In direct-heated diodes, the cathode and filament form a single piece that is of great importance in power rectifiers.

83 - Supply current smoothing circuit.

84 - Thermoelectric rectifiers with direct and indirect heating cathodes.