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rdet

rdet

I want this to output 4 volt
2y
rdet

rdet

@copilot explain this project.
2y

copilot

This project is a 5V fixed output linear voltage regulator circuit, implemented using the STMicroelectronics' L7805CV IC. The L7805CV voltage regulator takes an input voltage up to 35V and outputs a constant 5V.
The main components and how they are connected are as follows:
  • The voltage regulator U1, the L7805CV, with three pins:
    • IN for the input voltage (connected to VIN)
    • GND for grounding
    • OUT for the output 5V regulated voltage.
  • Two capacitors, C1 and C2, which are used for input and output decoupling:
    • C1 (0.33uF), connected between the input voltage (VIN) and ground, to filter noise on the input.
    • C2 (0.1uF), connected between the output (5V) and ground, to filter noise on the output.
  • Four connectors, J1, J2, J3, J4:
    • J1 and J2, connected to the input, allows for two different ways to provide input power to the circuit.
    • J3 and J6 allow for two possible output connections.
  • Connectors J5 and J4 are used for grounding (GND).
The goal of this circuit is to provide a steady 5V output, even when the input voltage might fluctuate. It's a basic power supply circuit and it's particularly useful in many electronic devices requiring a stable power source.
2y
rdet

rdet

I want this to output 4 volt
2y

copilot

To obtain a 4V output from a linear regulator, one method is to use a Low-dropout regulator (LDO) like the LD1117V33 that can provide 3.3V output, and then add a silicon diode like 1N4001 in series with its output. The diode introduces a ~0.7V voltage drop which when added to the 3.3V results in around 4V output.
However, it's important to recognize that diodes do not provide a stable voltage drop, it varies with the current passing through it. Therefore, the output will not be stable at 4V and will change if the load changes.
Here is how the schematic would appear with the proposed changes:
  1. Replace the L7805CV with LD1117V33, a 3.3V linear regulator. Connect PIN1(IN) of U1 to VIN, PIN2(GND) to GND and PIN3(OUT) to one end of the diode.
  2. Connect anode of 1N4001 diode to the LD1117V33 output, and the cathode would be connected to C2 and the rest of the 4V output circuit.
Your resulting line regulator portion of the circuit would look like this:
VIN -> C1 -> U1:PIN1 - -> U1:PIN2 -> GND -> U1:PIN3 -> Cathode of 1N4001 Diode -> Anode of 1N4001 Diode -> C2 (0.1uF) -> 4V Net
Remember to change any reference from "5V" in your project to "4V". The exact output voltage will depend on the load and the exact forward voltage of the diode (which varies depending on the current passing through it).
2y
Someone is typing...
3
@docbrown can you please check for any differences between this schematic and th...

docbrown

Of course! I have analyzed both schematics and found the following differences between the L7805 Fixed Output Regulator schematic provided here and the typical application schematic from the L7805CV datasheet:
  1. Input/Output connectors: The provided schematic has multiple input/output connectors, including JST connectors (J3 and J6), terminal block connectors (J1 and J4), and pin headers (J2 and J5). The datasheet schematic does not have these connectors specified.
  2. Capacitors values: The provided schematic uses different capacitance values for input and output capacitors. C1 (input capacitor) has a value of 0.33uF, while C2 (output capacitor) has a value of 0.1uF. The L7805CV datasheet suggests using 0.33uF for the input capacitor (Cin) and 0.1uF for the output capacitor (Cout), but also mentions that capacitor values may be increased without any problems.
Other than these differences, the provided schematic is consistent with the typical application schematic from the L7805CV datasheet. Please note that different manufacturers may specify different recommended capacitance values, so it's essential to consult the datasheet of the specific L7805CV part you are using.
3y
vasy_skral

vasy_skral

@docbrown can you please check for any differences between this schematic and the schematic from L7805CV datasheet?
3y
Someone is typing...
1
J1
C2
Capacitance
0.1uF
J4
C1
Capacitance
0.33uF
U1
J5
J2
4
New Comment
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  • Ground
    Ground
    A common return path for electric current. Commonly known as ground.
    jharwinbarrozo
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  • Generic Resistor
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  • Generic Capacitor
    Generic Capacitor
    A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF, 10pF, 100pF, 1000pF, 0.01uF, 0.1uF, 1.0uF, 10uF, 100uF, 1000uF, 10000uF 1.1pF, 11pF, 110pF, 1100pF 1.2pF, 12pF, 120pF, 1200pF 1.3pF, 13pF, 130pF, 1300pF 1.5pF, 15pF, 150pF, 1500pF, 0.015uF, 0.15uF, 1.5uF, 15uF, 150uF, 1500uF 1.6pF, 16pF, 160pF, 1600pF 1.8pF, 18pF, 180pF, 1800pF 2.0pF, 20pF, 200pF, 2000pF 2.2pF, 22pF, 220pF, 2200pF, 0.022uF, 0.22uF, 2.2uF, 22uF, 220uF, 2200uF 2.4pF, 24pF, 240pF, 2400pF 2.7pF, 27pF, 270pF, 2700pF 3.0pF, 30pF, 300pF, 3000pF 3.3pF, 33pF, 330pF, 3300pF, 0.033uF, 0.33uF, 3.3uF, 33uF, 330uF, 3300uF 3.6pF, 36pF, 360pF, 3600pF 3.9pF, 39pF, 390pF, 3900pF 4.3pF, 43pF, 430pF, 4300pF 4.7pF, 47pF, 470pF, 4700pF, 0.047uF, 0.47uF, 4.7uF, 47uF, 470uF, 4700uF 5.1pF, 51pF, 510pF, 5100pF 5.6pF, 56pF, 560pF, 5600pF 6.2pF, 62pF, 620pF, 6200pF 6.8pF, 68pF, 680pF, 6800pF, 0.068uF, 0.68uF, 6.8uF, 68uF, 680uF, 6800uF 7.5pF, 75pF, 750pF, 7500pF 8.2pF, 82pF, 820pF, 8200pF 9.1pF, 91pF, 910pF, 9100pF #generics #CommonPartsLibrary
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  • Generic Inductor
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L7805 Fixed output regulator

L7805 Fixed output regulator thumbnail
Linear Voltage Regulator with 1 Positive Fixed Output 5.0V. Input voltage 35V max With JST connectors(Vin and +5V) and with block terminal connectors(Vin and +5V) #project-template #voltageregulator #project

Properties

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Pricing & Availability

Distributor

Qty 1

Digi-Key

$0.38–$0.90

LCSC

$0.19–$0.31

Mouser

$0.69

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