Simple continuity tester

Posted on Feb 10, 2013

The pitch of the tone is dependent upon the resistance under test. The tester will respond to resistance of hundreds of kilohms, yet it is possible to distinguish differences of just a few tens of ohms in low-resistance circuits. Ql and Q2 form a multivibrator, the frequency of which is influenced by the resistance between the test points.

Simple continuity tester
Click here to download the full size of the above Circuit.

The output stage Q3 and Q4 will drive a small loudspeaker or a telephone earpiece.

Leave Comment

characters left:

New Circuits



Popular Circuits

Tone detector
how to make solar powered robot
phone cut circuit
tan timer schematics
Dual Power Amplifier Using TDA7293 MOSFET IC
40W Fluorescent Lamp Inverter
Glow Plug Driver for R/C Flightbox