This Audio booster circuit is very simple and can be applied to fm tuner or audio pre amplifier. The 2N3392 is a low-noise type transistor in TO-92 case. The transistor can can be replaced by a NTE199 or ECG199. If you wish to use a TUN, cross reference the parameters with one of the units from this list : TUP-TUN
Potentiometer R5 of 100K is a linear type with an on/off switch attached. The value of C1 may need to be between 0.05µF and 0.1µF (47nF/100nF). Experiment with the value for best performance.
Parts list : R1 : 47K R2 : 470K R3 : 10K R4 : 560 R5 : 100K potmeter+switch Linear R6 : 270 C1 : Capacitor, .05-.1μF Ceramic, 50V C2 : Capacitor, 0.1μF Ceramic, 50V C3 : Capacitor, 33μF/25V Electrolytic Q1 : 2N3392 Transistor, NPN LED1 LED, red 276-033 Ultra-Bright