In order to provide an output voltage higher than that provided by the regulator to provide a voltage regulator integrated circuit is often necessary accordingly. One way to achieve this is to connect the "common" to the midpoint of the voltage divider, and the IC regulator small quiescent current coming out from the common terminal to ground The problem with this method (~ 10 mA it is to have).
Since the extent of this quiescent current is not strictly controlled, the total output voltage will be somewhat unpredictable. There is a possibility of help resistor divider low value, is a complication of inefficiency and heat dissipation.
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| increase The Regulator Output Voltage Circuit |
24V from 12V regulator circuit diagram
The circuit presented here avoids the problem by using the transistor T1 to generate a low impedance at the regulator common terminal by emitter-follow action, while transferring the voltage divider from a relatively high-resistance divider network. The value of R3 is not critical but must be low enough to accept the highest quiescent current without causing T1 to turn-off.
