2 layers204.5 × 113 mm
2 layers74.4 × 73.9 mm
Bench power supply
HexFud/Bench-power-supplyI designed a simple and cost effective bench power supply for everyone. To simplify the assmebly process i designed in kicad a small pcb where you connect external components
- Size
- 74.4 × 73.9 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 31
- Nets
- 44
- Pads
- 108
- Tracks, vias
- 269, 48
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 19 Sep 2026
- Updated
- 12 Oct 2026
Overview
Bench power supply is an open-source printed circuit board by HexFud, from the HexFud/Bench-power-supply repository on GitHub. It is a 2-layer board of 74.4 × 73.9 mm with 31 parts on 44 nets, routed with 269 tracks and 48 vias.
It is built around the LM2596S-12, AMS1117-3.3 and SMBJ36A. Its parts include 10 connectors, 5 capacitors, 3 diodes, 2 resistors and 2 ICs. It belongs with the power boards and the ESP32 and AVR (ATmega, ATtiny) boards of this library.
Main components
3
LM2596S-12
TO-263-5L-20℃~+70℃ 1 12V 170kHz 2mA 3A 4.5V~40V Buck Buck Built-in Fixed No TO-263-5L DC-DC Converters ROHSGRDC-DC Converters
AMS1117-3.3
SOT-223-40℃~+125℃ 0.003%Vout 1 1.1V@(800mA) 15V 1A 3.3V 5mA 72dB@(120Hz) Fixed Over Current Protection、Short Circuit Protection、Thermal shutdown Positive SOT-223 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSAdvanced Monolithic SystemsVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
SMBJ36A
SMB10.4A@10/1000us 1uA 36V 390pF 44.2V 58.1V 600W@10/1000us TVS SMB ESD and Surge Protection (TVS/ESD) ROHS晶导微电子ESD And Surge Protection (TVS/ESD)
README
README.mdBench-power-supply
I designed a simple and cost effective bench power supply for everyone. To simplify the assmebly process i designed in kicad a small pcb where you connect external components
Specifications
- IN Voltage: 24V DC
- Power Module: compatible with buck modules CC/CV based on XL4015 (5A) or XL4016 (8A)
Included Protections
- 6.3A fusible
- schottky diode to protect against invers polarity
- filtering capacitor
First power-up
- Do not plug the Nano, the DPS and the displays yet.
- Power the PCB with 24V and check the 12V rail after the LM2596 and the 3V3 rail.
- Power off, plug everything in, and power on again with no load on the output.
- The output stays OFF at boot; enable it with a long press on the voltage encoder.
Firmware
- Arduino IDE, board "Arduino Nano ESP32"
- Libraries: Adafruit SSD1306, Adafruit GFX Library
- Firmware:
Firmware/bench_psu.ino - Register addresses and scales are constants at the top of the sketch: check them against the protocol document of your DPS module.
⚠️ Crucial Assembly Notes
- Modifying the Buck Converter: To mount the voltage and current controls on the front panel, you must physically desolder the original tiny blue trimmers from the purchased Buck module. Solder wires into those remaining through-holes and route them to your front-panel potentiometers.
- Display Wiring (CRITICAL - DO NOT BURN YOUR DISPLAY):
When using the standard 5-wire Chinese dual meters (3 thin wires, 2 thick wires), THE THIN BLACK WIRE MUST BE LEFT UNCONNECTED. The meter derives its ground reference entirely through the thick black wire. Connecting both black wires creates a ground loop that will melt the thin wire instantly under load. (Connector
J8on this PCB is purposely designed with only 3 pins for the thin wires). - High-Current Traces: The PCB tracks handling the 24V input, the Buck module, and the outputs carry up to 5–8A. When routing the PCB, ensure power traces are made very wide (min. 2mm–3mm) or left exposed so you can reinforce them with solder.
Parts
31| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | MountingHole_Pad | MountingHole:MountingHole_3.2mm_M3_DIN965_Pad | H1, H2, H3, H4 |
| 2 | 10k | Resistor_SMD:R_0805_2012Metric | R1, R2 |
| 2 | Conn_01x01_Socket | TestPoint:TestPoint_Pad_D3.0mm | J3, J4 |
| 2 | Conn_01x03_Socket | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J5, J6 |
| 2 | Conn_01x04_Socket | Connector_PinSocket_2.54mm:PinSocket_1x04_P2.54mm_Vertical | J2, J8 |
| 2 | Conn_01x05_Socket | Connector_PinSocket_2.54mm:PinSocket_1x05_P2.54mm_Vertical | J9, J10 |
| 2 | SW_SPST | TerminalBlock_Phoenix:TerminalBlock_Phoenix_MKDS-1,5-2-5.08_1x02_P5.08mm_Horizontal | SW1, SW2 |
| 1 | 1000uF 50V | Capacitor_THT:CP_Radial_D12.5mm_P5.00mm | C1 |
| 1 | 100nF 50V | Capacitor_SMD:C_0805_2012Metric | C2 |
| 1 | 100uF 30V | Capacitor_THT:CP_Radial_D6.3mm_P2.50mm | C3 |
| 1 | 220uF 50V | Capacitor_THT:CP_Radial_D8.0mm_P3.50mm | C5 |
| 1 | 22uF 10V | Capacitor_SMD:C_0805_2012Metric | C4 |
| 1 | 24V | TerminalBlock_Phoenix:TerminalBlock_Phoenix_MKDS-1,5-2-5.08_1x02_P5.08mm_Horizontal | J1 |
| 1 | 6,3A | Fuse:Fuseholder_Cylinder-5x20mm_Bulgin_FX0457_Horizontal_Closed | F1 |
| 1 | AMS1117-3.3 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U3 |
| 1 | Arduino_Nano_ESP32 | Module:Arduino_Nano | A1 |
| 1 | Conn_01x04_Socket | TerminalBlock_Phoenix:TerminalBlock_Phoenix_MKDS-1,5-4-5.08_1x04_P5.08mm_Horizontal | J7 |
| 1 | D_Schottky | Diode_SMD:D_SMA | D3 |
| 1 | L | Inductor_SMD:L_Bourns_SRR1260 | L1 |
| 1 | LED | LED_SMD:LED_0805_2012Metric | D2 |
| 1 | LM2596S-12 | Package_TO_SOT_SMD:TO-263-5_TabPin3 | U5 |
| 1 | SMBJ36A | Diode_SMD:D_SMB | D1 |
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Questions
How big is the Bench power supply PCB?
It measures 74.4 × 73.9 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Bench power supply use?
31 parts, built around the LM2596S-12, AMS1117-3.3 and SMBJ36A. 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 Bench power supply KiCad files?
From the HexFud/Bench-power-supply repository on GitHub, at the commit this page was made from: the board is PCB/Bench_Power_supply.kicad_pcb and its schematic PCB/Bench_Power_supply.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Bench power supply design in my own project?
Its repository states no licence, so its author keeps all rights: ask HexFud before reusing the design.