Component selection of transistor regulated power supply
The steps for selecting components in this circuit are similar to those of a parallel silicon regulator circuit, mainly considering the following aspects.
(1) Preliminary selection of adjusting tube T1 and stabilizing tube D1
When selecting the adjustment tube T1, the main consideration is that its rated current ICM should be greater than the output current IO to ensure that the adjustment 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 to β High value, low leakage current. When selecting regulator D1, the main consideration is to ensure that the sum of its stable voltage and T1 emission junction voltage is equal to the output voltage.
(2) Selected input voltage
To ensure the efficiency of the regulated power supply, the input voltage should generally not be too high and should not exceed 2 UI.
(3) Selected current limiting resistor R2
For parallel voltage stabilizing circuits, the current limiting resistor R2 is the key to the overall operation of the circuit. If R2 is selected large, the voltage stabilization effect is good, but the power consumption is high (because the resistance power consumption P=I2R), and the input voltage is required to increase, the efficiency of the power supply is relatively low. The specific calculation method can refer to the third step of selecting components for parallel voltage stabilizing circuits of silicon voltage regulators.
(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 sufficient, R1 and UI can be appropriately increased, and there are also options β Adjustment tube with high value and low leakage current
