Can be built into penlight housing, using single penlight cell or 1.5-V mercury cell for power. Output probe for feeding signal to audio circuit under test is about linch length of stiff wire, pointed. For more output, run ground lead to equipment under test.Q1 can be HEP253, 2N519, 2N741A, 2N2929, or equivalent. Q2 can be HEP3, 2N1280, 2N2273, SK3005, or equivalent. Adjust R, and R, for good output, and ad just R3 as required for good tone.To use, touch probe to input of any receiver or high-fidelity audio circuit. Tone should be heard from loudspeaker if circuit is good between probe and loudspeaken-C.J. Schauers, Transistorized Signal Tracer, CQ4 Sept. 1973, p 12 and14.
Required Field 
