It is a regulated power supply with an output voltage adjustable from 0 to 12.5 V and a current of short circuit limited to 120 mA.Un second module is designed to power a voltmeter table.
The output voltage is adjustable from 0V. To achieve this value, you have to create a negative voltage.
U2 is the circuit that is responsible.
It is a LM317 with a TO92 case.
The reference voltage of the integrated circuit that produces the L200 output voltage of the mains supply is 2.77 V. We need the circuit U2 may provide a voltage of -2.77 V.
The reference voltage of the LM317 is 1.25 V typical which is found at the terminals of R9. Neglecting the bias current of U2, the output voltage will therefore
VO = 1.25 x [1 + (R7 + R8) / R9]
The resistor R7 sees greatness range from 0 to 100 ohms.
By performing numerical calculations, the voltage will change in VO
-2.5 V to -2.92 V.
The voltage regulation:
The L200 is responsible for producing the output voltage of the power supply. Its reference voltage between pin 4 and typical value for GND3 to 2.77 V. GND3 point being raised to a potential of -2.77 V minimum output voltage of the power laboratory can reach the ground potential (0V).
If we want a maximum voltage of 12.5 V output, the current in the 10k potentiometer will be 12.5 / 10,000 = 1.25 mA. Neglecting the bias current of the L200, this resistance between pin 4 and will GND3 2.77 V / 1.25 mA = 2.22 k
This resistance consists of R3 and R4 wired in series.
If we want a maximum output voltage different, simply recalculate the equivalent resistance R3 + R4.
A notice that the transformer is a 2 x 9V - 5VA. It is oversized for this application. It acts as a generator of Thévenin and its output voltage is greater in this case at face value. Therefore the differential voltage across the L200 provides an output voltage of 12.5 V.
The current limitation:
The current limitation operates when the ddp between pins 2 and 5 of L200 reached 0.45 V. The two resistors R1 and R2 are in parallel and équivatente resistance is 7.5 / 2 = 3.75 ohms. The short circuit is limited to 0.45 / 3.75 = 120 mA. Each resistor dissipates 54mW.
Manufacturing:
Installation is as low voltage 230V. The metal housing of the power supply must be connected to all parts of the earth. The plug 230 is a mandatory three-pin earthed. The cord will be a 3 x 2.5 mm ². Fixing the PCB will be carried out with four plastic spacers tapped M3 ..
The second power is expected to table a voltmeter liquid crystal, whose total supply must be isolated from the circuit ground. If it is not used in this sense, by recalculating the values of the two resistors R5 and R6, it can produce a voltage of 5V 100mA for example.
The use of this power covers most applications. The maximum voltage of 40V is L200, changing the processor and changing the component values R4 and R3 and capacitor voltages, one can obtain an output voltage ranging from 0 to 30V.
Setting:
It is done in two steps. 10k potentiometer is brought fully to the left (minimum), adjust R7 to obtain an output voltage of zero. The potentiometer is brought to a stop right (maximum value), adjust R4 to obtain an output voltage of 12.5 V.
All components are oversized. The power supply can withstand a permanent short-circuit.
Analysis of the pattern:
Reference no:
The output voltage is adjustable from 0V. To achieve this value, you have to create a negative voltage.
U2 is the circuit that is responsible.
It is a LM317 with a TO92 case.
The reference voltage of the integrated circuit that produces the L200 output voltage of the mains supply is 2.77 V. We need the circuit U2 may provide a voltage of -2.77 V.
The reference voltage of the LM317 is 1.25 V typical which is found at the terminals of R9. Neglecting the bias current of U2, the output voltage will therefore
VO = 1.25 x [1 + (R7 + R8) / R9]
The resistor R7 sees greatness range from 0 to 100 ohms.
By performing numerical calculations, the voltage will change in VO
-2.5 V to -2.92 V.
The voltage regulation:
The L200 is responsible for producing the output voltage of the power supply. Its reference voltage between pin 4 and typical value for GND3 to 2.77 V. GND3 point being raised to a potential of -2.77 V minimum output voltage of the power laboratory can reach the ground potential (0V).
If we want a maximum voltage of 12.5 V output, the current in the 10k potentiometer will be 12.5 / 10,000 = 1.25 mA. Neglecting the bias current of the L200, this resistance between pin 4 and will GND3 2.77 V / 1.25 mA = 2.22 k
This resistance consists of R3 and R4 wired in series.
If we want a maximum output voltage different, simply recalculate the equivalent resistance R3 + R4.
A notice that the transformer is a 2 x 9V - 5VA. It is oversized for this application. It acts as a generator of Thévenin and its output voltage is greater in this case at face value. Therefore the differential voltage across the L200 provides an output voltage of 12.5 V.
The current limitation:
The current limitation operates when the ddp between pins 2 and 5 of L200 reached 0.45 V. The two resistors R1 and R2 are in parallel and équivatente resistance is 7.5 / 2 = 3.75 ohms. The short circuit is limited to 0.45 / 3.75 = 120 mA. Each resistor dissipates 54mW.
structural scheme
artwork
plot plan components
Components:
Resistance Capacitor Integrated circuit Diode Transformer Picot | R1, R2 R3 R4 R5 R6 R7 R8, R9 C1 C2, C7, C8 C3, C4, C9 C5, C6 U1 U2, U3 D1 D2, D3 D4, D5 TR1 TR2 X0, X3, X4, XP1, XP2, X5, X6 | 7.5 / 250 mW 2.2 k 220 multi-adjustable vertical 240 1.5 k 100 Adjustable vertical mutitours 330 10 uF / 25 V 22 uF / 25V 100 uF / 25V 100 nF LM200CV vertical radiator + + nut + screw LM317 TO92 in 1A Bridge 1N4004 1N4148 2 x 9V - 5VA 9V - 1.5 VA | |||
Manufacturing:
Installation is as low voltage 230V. The metal housing of the power supply must be connected to all parts of the earth. The plug 230 is a mandatory three-pin earthed. The cord will be a 3 x 2.5 mm ². Fixing the PCB will be carried out with four plastic spacers tapped M3 ..
The second power is expected to table a voltmeter liquid crystal, whose total supply must be isolated from the circuit ground. If it is not used in this sense, by recalculating the values of the two resistors R5 and R6, it can produce a voltage of 5V 100mA for example.
The use of this power covers most applications. The maximum voltage of 40V is L200, changing the processor and changing the component values R4 and R3 and capacitor voltages, one can obtain an output voltage ranging from 0 to 30V.
Setting:
It is done in two steps. 10k potentiometer is brought fully to the left (minimum), adjust R7 to obtain an output voltage of zero. The potentiometer is brought to a stop right (maximum value), adjust R4 to obtain an output voltage of 12.5 V.
All components are oversized. The power supply can withstand a permanent short-circuit.
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