Circuit Regulated Linear Power Supply LM317
Normally begin to learn about electronics power supply from the battery, for example, 9 volts, 1.5 volts, 6 volts etc. But there are disadvantage that when using battery power is discharged. I need to buy a new one. Consume more.
We should the dc power supply have a choice of AC voltage. Which it must provide a output voltage as usage often is 1.5volt, 3 volts, 4.5 volts, 6v, 9v, and the current is about 1 A.
When we view many circuit ideas, found that the as figure this below (number second the power supply projects in my life) have the best fit. We use a dc voltage regulator number LM317T is the heart of the circuit. Featured, is the constant voltage. Low noise. Almost equal to the voltage of the battery. And short-circuit protection as well.
- When we push power switch (S1) on, the AC-line voltage will pass through a fuse F1 and come to transformer T1 to reduce AC volts down to 12 volts
- Then this current flow through the bridge diode model (D1-D4)-1N4001 to full wave rectifire as DC current and through C1 to filter current to smooth up and has C2 filter ripple signal before into LM317.
- LED to display power on the circuit, with R1(2K) currents to reduce it.
- The output voltage is determined by rotating a selector switch S2 a level voltage 1.5,3,4.5,5,6,9 volts respectively
- C5 (10uF) control impedance and reduce a transient at output of IC1
- C3 (10uF)- help to reduce the ripple before is amplified when the output voltage rise up.
- C4 (0.1uF) reduce the ripple at output.
- D5 and D6(1N4001) for protects IC1 from discharging of C3 and C5 respectively. In case the input of IC1 is shorted.
- The maximum output current about 1.5A depends on size of the transformer We sould choose size of 2A., Or size 1A for those who want to 1A output current only.