Continuity Tester based around a 555 IC

Thread Starter


Joined Apr 28, 2012
I am trying to build a continuity tester and have found the attached circuit diagram on the internet with good reviews. I have some confusion.

In the article they talk about a 12 Volt Pizeo Buzzer. However the circuit diagram shows an 8Ω Speaker so a little confused.

Would any additions or alterations be suggested

Thank you in advance



Joined Nov 30, 2010

Apply 5 to 15 volts DC to anything, with the negative end of the power supply connected to the ground of the circuit above, and connect the positive end of the circuit to the "anything". If continuity, then buzz.