This circuit is LM317 Low dropout regulator 5V 2A using TIP41, is Low dropout 5V regulator that use LM317 as main. It converts the input voltage from 5.1V DC into the 5V output, while the maximum output current is 2A by TIP41 increase current.
How it works
From this circuit: Low dropout voltage regulators circuits that can converted voltage input from 6V to 5V output, they use transistors as main components.
When we need a 5VDC power supply, but the level voltage input low 5.1V only. Which does not possible difficult. But this circuit can help us.
See the figure below! is LM317 Power supply that has Low Volt drop across lower 0.1V only. (The voltage input about 5.1V to 12V)
The LM317 is highly popular IC (3 terminal passive adjustable regulator IC). The voltage drop across adj pin and output pin is about 1.25V, and next LED1.
The LED1 glow which has voltage across both LED are 3.6V(1.8V+1.8V) and they serve as display power on of this circuit.
So, Voltage output around of 5 volts. These components will maintain voltage Regulated at the output as the feature of LM317 and both LED there.
Normally this circuit takes voltage input about 5.1V to 12V. Besides still have Q1-TIP42 PNP transistor serves as increasing current up to 2A
More low dropout regulator circuits
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