EngorioJuncSentry — Diode Junction & Continuity Tester
About this project
JuncSentry is an Arduino Uno-based diode junction and continuity tester that uses a precision 3.3 kΩ probe resistor to inject a controlled current (≤ 1.52 mA) into any device under test. The firmware reads the resulting forward voltage (Vf) on ADC pin A0 and classifies the DUT into five states: OPEN, CONTINUITY, SILICON DIODE, LED-LOW junction (red/yellow LED or germanium), or LED-HIGH junction (blue/white LED). A 3-LED colour code — green for continuity, yellow for a junction, red for open — gives instant visual feedback. A passive buzzer generates a continuous 880 Hz tone for wire continuity and 1, 2, or 3 beep sequences to identify the junction type. The 3.3 kΩ probe resistor limits injection current below 1.6 mA at all times, protecting both the ATmega328P pin and the component under test. A startup self-test flashes all three LEDs with an ascending tone sweep to verify output hardware before measurements begin.
What you get
- Complete, commented source code
- Full components list with quantities
- Pin-by-pin wiring guide and connection table
- Step-by-step upload and testing guide
- Project report (.docx, IEEE style)
- Presentation slides (.pptx)
