Abstract: An audible voltage-impedance tester for generating distinct sounds when its test probes are connected across an unknown source, be it a resistive source, a DC voltage source, an AC voltage source or combination thereof. No switching is required between resistive testing and voltage testing nor between DC voltage testing and AC voltage testing. The tester is able to generate distinct sounds for different resistance values, for different DC voltage amplitudes, for different AC voltages with the same frequency but different amplitudes, and for AC voltages with different frequencies but the same amplitudes.A visual indicator of the audible sound is disclosed along with circuitry that utilizes a multi-vibrator whose powered operation by a battery is not affected by the unknown source.