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Circuit Description:
In this circuit we are using transformer has capacity of 24 volt and 2 A current capacity that given at the output. Using bridge rectifier converts AC into DC and capacitor used for getting smooth dc voltage .LED used for indicate the power in the circuit the current through the led will be between 12 - 20mA at 2V depending on the type and color Led you are using. then smooth dc voltage apply to input terminal of voltage regulated IC LM317.variable resistor of 5 kilo ohm at adjust terminal of IC we can vary the voltage from 1.5v to 30 v .it is getting at the output terminal of IC .diode D1 is used as rectifier to block the current to flow in opposite direction. It steers any current that might be coming from the device under power around the regulator to prevent the regulator from being damaged Capacitor C2 used to filter any type of noise .also we use heat sink for IC because IC is heated during running of project. Maximum current is about 1.5 amps which is also sufficient for most of your tinkering. The large value of C1 makes for a good, low ripple output voltage. C2 is a 0.1µF (100nF) decoupler capacitor to filter out the transient noise which can be induced into the supply by stray magnetic fields. Under normal conditions this capacitor is only required if the regulator is far away from the filter cap, but I added it anyway. C3 improves transient response. This means that while the regulator may perform perfectly at DC and at low frequencies, (regulating the voltage regardless of the load current); at higher frequencies it may be less effective. Adding this 1 µF capacitor should improve the response at those frequencies.
APPLICATIONS INFORMATION LM 317
IC LM-317 (VOLTAGE REGULATED) DESCRIPTION:
The LM317 is an adjustable 3–terminal positive voltage regulator
Capable of supplying in excess of 1.5 a over an output voltage range of
1.2 V to 37 V. This voltage regulator is exceptionally easy to use and
Requires only two external resistors to set the output voltage
• Output Current in Excess of 1.5 A
• Output Adjustable between 1.2 V and 37 V
• Internal Thermal Overload Protection
• Internal Short Circuit Current Limiting Constant with Temperature
• Output Transistor Safe–Area Compensation
• Floating Operation for High Voltage Applications
• Available in Surface Mount D2PAK, and Standard 3–Lead Transistor
Package
• Eliminates stocking many Fixed Voltages
• C1 is required if regulator is located an appreciable distance from power supply filter.
• C2 is not needed for stability; however, it does improve transient response.
Features
• Guaranteed 1% output voltage tolerance
(LM317A)
• Y Guaranteed max. 0.01%/V line regulation
• (LM317A)
• Guaranteed max. 0.3% load regulation
(LM117)
• Guaranteed 1.5A output current
• Adjustable output down to 1.2V
• Current limit constant with temperature
• Pa Product Enhancement tested
• 80 dB ripple rejection
• Output is short-circuit protect.
Basic Circuit Operation:-
The LM317 is a 3–terminal floating regulator. In Operation, the LM317 develops and maintains a nominal 1.25 V reference (Vref) between its output and adjustment Terminals. This reference voltage is converted to a programming current (IPROG) by R1 and this Constant current flows through R2 to ground. The regulated output voltage is given by:
Since the current from the adjustment terminal (IAdj) represents an error term in the equation, the LM317 was designed to control IAdj to less than 100 mA and keep it constant. To do this, all quiescent operating current is returned to the output terminal. This imposes the requirement for a minimum load current. If the load current is less than this minimum, the output voltage will rise. Since the LM317 is a floating regulator, it is only the voltage differential across the circuit which is important to performance, and operation at high voltages with respect to
Ground is possible
Protection Diodes:-
When external capacitors are used with any IC regulator it is sometimes necessary to add protection diodes to prevent the capacitors from discharging through low current points into the regulator the LM317 with the recommended protection diodes for output voltages in excess of 25 V or high capacitance values (CO > 25 mF, CAdj > 10 mF). Diode D1 prevents CO from discharging thru the IC during an input short circuit. Diode D2 protects against capacitor CAdj discharging through the IC during an output short circuit. The combination of diodes D1 and D2 prevents CAdj from discharging through the IC during an input short circuit
External Capacitors:-
An input bypass capacitor is recommended. A 0.1 mF disc or 1 mF solid tantalum on the input is suitable input bypassing for almost all applications. The device is more sensitive
To the absence of input bypassing when adjustment or output capacitors are used but the above values will eliminate the possibility of problems. The adjustment terminal can be bypassed to ground on the LM117 to improve ripple rejection. This bypass capacitor
Prevents ripple from being amplified as the output voltage is increased. With a 10 mF bypass capacitor 80 dB ripple rejection is obtainable at any output level. Increases over 10 mF do not appreciably improve the ripple rejection at frequencies above 120 Hz. If the bypass capacitor is used, it is sometimes necessary to include protection diodes to prevent the capacitor from discharging through internal low current paths and damaging the device.
Load Regulation:-
The LM317 is capable of providing extremely good load regulation, but a few precautions are needed to obtain maximum performance. For best performance, the programming resistor (R1) should be connected as close to the regulator as possible to minimize line drops which effectively appear in series with the reference, thereby degrading regulation. The ground end of R2 can be returned near the load ground to provide remote ground sensing and improve load regulation
In this circuit we are using transformer has capacity of 24 volt and 2 A current capacity that given at the output. Using bridge rectifier converts AC into DC and capacitor used for getting smooth dc voltage .LED used for indicate the power in the circuit the current through the led will be between 12 - 20mA at 2V depending on the type and color Led you are using. then smooth dc voltage apply to input terminal of voltage regulated IC LM317.variable resistor of 5 kilo ohm at adjust terminal of IC we can vary the voltage from 1.5v to 30 v .it is getting at the output terminal of IC .diode D1 is used as rectifier to block the current to flow in opposite direction. It steers any current that might be coming from the device under power around the regulator to prevent the regulator from being damaged Capacitor C2 used to filter any type of noise .also we use heat sink for IC because IC is heated during running of project. Maximum current is about 1.5 amps which is also sufficient for most of your tinkering. The large value of C1 makes for a good, low ripple output voltage. C2 is a 0.1µF (100nF) decoupler capacitor to filter out the transient noise which can be induced into the supply by stray magnetic fields. Under normal conditions this capacitor is only required if the regulator is far away from the filter cap, but I added it anyway. C3 improves transient response. This means that while the regulator may perform perfectly at DC and at low frequencies, (regulating the voltage regardless of the load current); at higher frequencies it may be less effective. Adding this 1 µF capacitor should improve the response at those frequencies.
APPLICATIONS INFORMATION LM 317
IC LM-317 (VOLTAGE REGULATED) DESCRIPTION:
The LM317 is an adjustable 3–terminal positive voltage regulator
Capable of supplying in excess of 1.5 a over an output voltage range of
1.2 V to 37 V. This voltage regulator is exceptionally easy to use and
Requires only two external resistors to set the output voltage
• Output Current in Excess of 1.5 A
• Output Adjustable between 1.2 V and 37 V
• Internal Thermal Overload Protection
• Internal Short Circuit Current Limiting Constant with Temperature
• Output Transistor Safe–Area Compensation
• Floating Operation for High Voltage Applications
• Available in Surface Mount D2PAK, and Standard 3–Lead Transistor
Package
• Eliminates stocking many Fixed Voltages
• C1 is required if regulator is located an appreciable distance from power supply filter.
• C2 is not needed for stability; however, it does improve transient response.
Features
• Guaranteed 1% output voltage tolerance
(LM317A)
• Y Guaranteed max. 0.01%/V line regulation
• (LM317A)
• Guaranteed max. 0.3% load regulation
(LM117)
• Guaranteed 1.5A output current
• Adjustable output down to 1.2V
• Current limit constant with temperature
• Pa Product Enhancement tested
• 80 dB ripple rejection
• Output is short-circuit protect.
The LM317 is a 3–terminal floating regulator. In Operation, the LM317 develops and maintains a nominal 1.25 V reference (Vref) between its output and adjustment Terminals. This reference voltage is converted to a programming current (IPROG) by R1 and this Constant current flows through R2 to ground. The regulated output voltage is given by:
Since the current from the adjustment terminal (IAdj) represents an error term in the equation, the LM317 was designed to control IAdj to less than 100 mA and keep it constant. To do this, all quiescent operating current is returned to the output terminal. This imposes the requirement for a minimum load current. If the load current is less than this minimum, the output voltage will rise. Since the LM317 is a floating regulator, it is only the voltage differential across the circuit which is important to performance, and operation at high voltages with respect to
Ground is possible
Protection Diodes:-
When external capacitors are used with any IC regulator it is sometimes necessary to add protection diodes to prevent the capacitors from discharging through low current points into the regulator the LM317 with the recommended protection diodes for output voltages in excess of 25 V or high capacitance values (CO > 25 mF, CAdj > 10 mF). Diode D1 prevents CO from discharging thru the IC during an input short circuit. Diode D2 protects against capacitor CAdj discharging through the IC during an output short circuit. The combination of diodes D1 and D2 prevents CAdj from discharging through the IC during an input short circuit
External Capacitors:-
An input bypass capacitor is recommended. A 0.1 mF disc or 1 mF solid tantalum on the input is suitable input bypassing for almost all applications. The device is more sensitive
To the absence of input bypassing when adjustment or output capacitors are used but the above values will eliminate the possibility of problems. The adjustment terminal can be bypassed to ground on the LM117 to improve ripple rejection. This bypass capacitor
Prevents ripple from being amplified as the output voltage is increased. With a 10 mF bypass capacitor 80 dB ripple rejection is obtainable at any output level. Increases over 10 mF do not appreciably improve the ripple rejection at frequencies above 120 Hz. If the bypass capacitor is used, it is sometimes necessary to include protection diodes to prevent the capacitor from discharging through internal low current paths and damaging the device.
Load Regulation:-
The LM317 is capable of providing extremely good load regulation, but a few precautions are needed to obtain maximum performance. For best performance, the programming resistor (R1) should be connected as close to the regulator as possible to minimize line drops which effectively appear in series with the reference, thereby degrading regulation. The ground end of R2 can be returned near the load ground to provide remote ground sensing and improve load regulation
longer lead on led is positive
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