【Daily Question 20090204】What is the difference between a self-enclosed transformer-type voltage regulator and a tube-based voltage regulator?

A tube regulated power supply is constructed such that the cathode and anode of the beam tetrod G↓[1] are connected to the negative and positive terminals of a auxiliary power supply, respectively; the positive terminal of this auxiliary power supply is connected to the load resistor R↓[2] of the comparison amplifier tube G↓[2]. It enables audio equipment to produce sound with a good timbre, is not vulnerable to sudden short circuits, offers high reliability and easy maintenance, improves electrical performance, reduces the proportion of higher harmonic components in the output voltage, results in a low amplitude of ripple voltage, features low dynamic impedance at both high and low frequencies, and provides an improved high-frequency response. The working principle of the autotransformer-type voltage regulator is to utilize the windings of the autotransformer in order to make either the primary side voltage or the secondary side voltage adjustable; the range of adjustment is relatively large, but it has no significant effect on improving the quality of the power supply

Voltage-stabilizing power supplies that utilize autotransformers include the \"magnetic amplifier-type electronic AC voltage stabilizer\" which was popular in China in the 1950s; today, there are also those with autotransformer (turn-ratio) adjustment. The main types are as follows: 1. Mechanical voltage regulation type, in which a servo motor drives carbon brushes to move along the winding surface of the autotransformer, thereby changing the ratio of Vo to Vi and achieving adjustment and stabilization of the output voltage. Such voltage regulators can range from a few hundred watts to several kilowatts. It is characterized by a simple structure, low cost, and minimal distortion of the output waveform ； However, since the sliding contacts of the carbon brushes easily generate electric sparks, this can cause damage to the brushes and even lead to their burnout and failure ； Moreover, the voltage adjustment speed is slow. 　　2. Change the tap type by equipping the autotransformer with multiple fixed taps, and use relays or thyristors (solid-state relays) as switches to automatically change the tap position, thereby achieving stability in the output voltage. 　　The advantages of this type of voltage regulator are its simple circuit design, wide voltage regulation range (130V–280V), high efficiency (≥95%), and low cost. The disadvantage is its low voltage regulation accuracy (±8–10%) and short service life; it is suitable for powering air conditioners in households. Tube AC regulated power supplies are of the magnetically saturated type, consume a lot of power, and have been phased out.