Versatile Audible Continuity tester

Parts list:
Q1 – BC547B – NPN Transistor
Q2 – BC557B – PNP Transistor

R1 –  56K ohms  – Resistor
R2 – 10K ohms – Resistor
R3 – 100 ohms – Resistor
R4 – 1K ohms – Resistor
R5 – 2.5K ohms – Variable Resistor
C1 – 47KPF capacitor
D1,D2 – IN4148 – Diodes
B – 9V Battery
SG1 – Piezo ceramic Buzzer

Circuit description

•A & B – test probes

•Audible continuous tone will be heard when probes A & B are connected to a component under test

•No tone heard from buzzer when no continuity is established in the component under test

•Audible tone – continuity is ok

•No audible tone – no continuity R5 can be adjusted for sensitivity of the circuit

It is very easy to assemble and use it.