2 layers
Nrf bga
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12 parts14kMIT
2 layers80 × 45 mm
Second Order Low Pass Filter Ac
Hawk453/Active-Low-Pass-Filter-PCBPCB design of Active LPF using KiCAD
- Size
- 80 × 45 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 12
- Nets
- 11
- Pads
- 34
- Tracks, vias
- 29, 1
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 26 May 2025
- Updated
- 27 May 2025
Overview
Second Order Low Pass Filter Ac is an open-source printed circuit board by Hawk453, from the Hawk453/Active-Low-Pass-Filter-PCB repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 80 × 45 mm with 12 parts on 11 nets, routed with 29 tracks and 1 via.
Its parts include 4 resistors, 3 connectors, 2 capacitors and 1 IC.
README
README.mdSecond-Order Active Low-Pass Filter (LM741)
Overview
This project implements a second-order active low-pass filter using the LM741 operational amplifier. The filter is designed in KiCad and is suitable for basic signal conditioning and noise filtering applications.
The filter attenuates frequencies above a specified cutoff frequency (fc) while allowing lower-frequency signals to pass with minimal attenuation.
Schematic
PCB Layout
Here’s a preview of the designed PCB:
The filter circuit is built using a Sallen-Key topology and includes:
- Op-Amp: LM741 (U1)
- Resistors: R1, R2, R3, R4
- Capacitors: C1, C2
- Input/Output: J1, J2 (Coaxial connectors), J3 (Pin connector)
- Power Supply: ±10V
(Replace component values and results below with your actual design)
| Component | Value |
|---|---|
| R1 | 3.3 kΩ |
| R2 | 3.3 kΩ |
| R3, R4 | 10 kΩ |
| C1 | 10 nF |
| C2 | 10 nF |
| Cutoff | ~4.8 kHz |
Files Included
📁 KiCad Project Files
- Schematic:
Second_Order_Low_Pass_Filter_Ac.kicad_sch - PDF Schematic:
Second_Order_Low_Pass_Filter_Ac.pdf - PCB Layout:
Second_Order_Low_Pass_Filter_Ac.kicad_pcb
📁 Fabrication Files
- Gerber Files: Ready for PCB manufacturing.
- Drill files and fabrication layers included.
📁 Bill of Materials (BOM)
- Can be generated from KiCad (
Tools->Generate BOM).
How to Use
-
View Schematic and PCB
- Open
.kicad_schand.kicad_pcbfiles in KiCad (v9.0.2 or newer).
- Open
-
Simulate (Optional)
- Export netlist and simulate in a tool like LTspice or use KiCad’s simulator for basic analysis.
-
Fabricate PCB
- Use the included Gerber files to manufacture the PCB through a PCB fabrication service.
-
Assemble the Circuit
- Solder components as per the schematic and BOM.
- Power the board using ±10V.
-
Test the Filter
- Apply test signals and verify the cutoff frequency response using an oscilloscope or signal analyzer.
Notes
- The LM741 is a general-purpose op-amp with limited bandwidth. For high-frequency applications, consider alternatives like TL072 or LM358.
- This filter is ideal for audio applications or low-frequency signal conditioning tasks.
License
GPL 3.0
Acknowledgments
Special thanks to the KiCad community for making open-source hardware design accessible!
Parts
12| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | R | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R1, R2, R3, R4 |
| 2 | C | Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P5.00mm | C1, C2 |
| 2 | Conn_Coaxial | Connector_Coaxial:BNC_TEConnectivity_1478035_Horizontal | J1, J2 |
| 1 | Conn_01x02_Pin | Connector:Banana_Jack_2Pin | J3 |
| 1 | LM741 | Package_DIP:DIP-8_W7.62mm_LongPads | U1 |
The 10 most common of 12 parts.
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Questions
How big is the Second Order Low Pass Filter Ac PCB?
It measures 80 × 45 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Second Order Low Pass Filter Ac use?
12 parts. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Second Order Low Pass Filter Ac KiCad files?
From the Hawk453/Active-Low-Pass-Filter-PCB repository on GitHub, at the commit this page was made from: the board is Second_Order_Low_Pass_Filter_Ac.kicad_pcb and its schematic Second_Order_Low_Pass_Filter_Ac.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Second Order Low Pass Filter Ac design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).