Component selection for transistor regulated power supply
The steps for selecting components in this circuit are similar to those of the silicon voltage regulator tube parallel voltage stabilizing circuit, mainly considering the following aspects.
(1) Preliminary adjustment tube T1 and voltage regulator tube D1
When selecting the regulating tube T1, the main consideration is that its rated current ICM should be greater than the output current IO to ensure that the regulating tube will not be damaged due to excessive current when the load is open. In addition, in order to ensure that the adjustment tube has a good adjustment effect, it is also required that the β value is large and the leakage current is small. When selecting the voltage regulator tube D1, the main consideration is that the sum of its stable voltage and the T1 emitter junction voltage must be equal to the output voltage.
(2) Selected input voltage
In order to ensure the efficiency of the regulated power supply, the input voltage should generally not be set too high and should not exceed 2 UI.
(3) Select current limiting resistor R2
For a parallel voltage stabilizing circuit, the current limiting resistor R2 is the key to the working quality of the entire circuit. The larger the R2 selection, the better the voltage stabilization effect, but the power consumption is large (because the resistor power consumption P=I2R), and the input voltage is required to increase, so the efficiency of the power supply is relatively low. For specific calculation methods, please refer to the third step of selecting silicon voltage regulator tube parallel voltage stabilization circuit components.
(4) Check circuit stability
The stability of the entire circuit needs to be determined based on the actual circuit requirements. If the stability is not enough, you can increase R1 and UI appropriately, and you can also choose a regulating tube with a larger β value and smaller leakage current.
Circuit principle analysis of transistor regulated power supply
A parallel regulated power supply using a composite regulator tube. The biggest difference in the circuit is that the regulator tube is changed to conform to the tube structure, so that a larger β value can be obtained and a larger ICM can be obtained. A similar method can be used when selecting components, but since the current of this circuit is relatively large, it should be noted that in addition to the resistance value, the power of the current-limiting resistor R1 should also be considered when selecting it. To avoid burning out the current limiting resistor when the load is disconnected.
Advantages and Disadvantages of Parallel Stabilized Power Supply
Advantages of parallel regulated power supply:
1. It has overload self-protection function, and the adjustment tube will not be damaged when the output is short-circuited.
2 When the load changes are small, the voltage stabilization performance is relatively good.
3. Good adaptability to instantaneous changes.
Disadvantages of parallel voltage stabilizing circuit:
1 The efficiency is low, especially at light load, almost all the electric energy is consumed in the current limiting resistor and adjustment tube.
2 The output voltage adjustment range is very small.
3 It is not easy to achieve high stability.
