Bug Detector With Beep

Schematic



Parts

1. R1 ( 390 ohm, 5% )
2. R2 ( 390 ohm, 5% )
3. C1 ( 1000 uF, 10V )
4. C2 ( 1.5 uF, 10V )
5. C3 ( 3.9 nF )
6. C4 ( 20 pF, Trimmer )
7. C5 ( 10 nF / 0.01uF or 103 )
8. IC1, IC2 ( 7413 or 74LS13 )

Source: uoguelph