Logic probe
About the Logic probe PCB
Logic probe is an open source PCB design by akmalbnazir, published on GitHub. It is a 2-layer board measuring 49.8 × 25.6 mm, with 12 components from 10 distinct parts.
Other key parts include the 74HC14. By type, the board carries 3 diodes, 3 resistors, 2 connectors, 2 capacitors, 1 IC and 1 fuse.
From the project
A USB-powered digital logic probe built in KiCad
A simple but powerful USB-powered logic probe built in KiCad. This compact tool visually detects whether a digital signal is HIGH or LOW using two LEDs — great for debugging microcontroller pins, communication lines, or basic digital logic gates.
- ✅ USB-C powered — no external batteries - 🔴 Red LED lights when signal is LOW - 🟢 Green LED lights when signal is HIGH - 🔁 Built with a 74HC14 Schmitt Trigger inverter - 🔥 Protected by a PTC resettable fuse and Schottky diode - 🧪 Voltage divider ensures safe signal detection - 🛡️ Ground-referenced probe tip with pull-down resistor - 💡 Fits on a…
Main components on the Logic probe
Logic probe bill of materials (BOM)
12 components, 10 distinct parts.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | 74HC14 | SOIC-14_3.9x8.7mm_P1.27mm | U1 |
| 1 | USB_B_Micro | USB_Micro-B_Molex-105017-0001 | J1 |
| 1 | Conn_01x01 | PinHeader_1x01_P2.54mm_Vertical | J2 |
| 1 | 500mA-1A | Fuse_1206_3216Metric | F1 |
| 1 | SS14 | D_SMA | D1 |
| 2 | LED | LED_0603_1608Metric | D2, D3 |
| 1 | 10µF | C_0603_1608Metric | C1 |
| 1 | 0.1µF | C_0603_1608Metric | C2 |
| 1 | 10kΩ | R_0603_1608Metric | R1 |
| 2 | 220Ω | R_0603_1608Metric | R2, R3 |
Logic probe design files
The KiCad project lives in the akmalbnazir/logic-probe-pcb repository on GitHub; these links point at the commit this page was built from.
- Layoutlogicprobetool.kicad_pcb
- Schematiclogicprobetool.kicad_sch
Logic probe: common questions
How big is the Logic probe PCB?
The Logic probe measures 49.8 × 25.6 mm, has 2 copper layers and is 1.6 mm thick.
How many components are on the Logic probe?
12 components, from 10 distinct parts. The full bill of materials is listed on this page.
Where can I download the Logic probe design files?
From the akmalbnazir/logic-probe-pcb repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.
Can I use the Logic probe design in my own project?
The repository has no license, so all rights stay with akmalbnazir. Use it as a reference, and ask the author before reusing the design.