Extreme Circuits

Circuit Design Blogger

Audio Booster

Small and portable unit, Can be built on a veroboard

The amplifier’s gain is nominally 20 dB. Its frequency response is determined primarily by the value of just a few components-primarily C1 and R1. The values of the schematic diagram provide a response of ±3.0 dB from about 120 Hz to better than 20,000 Hz.Actually, the frequency response is ruler flat from about 170 Hz to well over 20,000 Hz; it’s the low end that deviates from a flat frequency response. The low end’s roll-off is primarily a function of capacitor C1(since RI’s resistive value is fixed). If C1’s value is changed to 0.1 pF, the low end’s comer frequency-the frequency at which the low-end roll-off starts-is reduced to about 70 Hz. If you need an even deeper low-end roll-off, change C1 to a 1.0 pF capacitor; if it’s an electrolytic type, make certain that it’s installed into the circuit with the correct polarity, with the positive terminal connected to Q1’s base terminal.

Audio Booster Circuit Diagram

Audio Booster Circuit Diagram


P1 = 100K
R1 = 47K
R2 = 470K
R3 = 10K
R4 = 560R
R5 = 270R
C1 = 0.1uF-25v
C2 = 3.3uF-25v
C3 = 470uF-25V
D1 = 5mm. Red Led
B1 = 9v Battery
J1 = RCA Audio Input Socket
J2 = RCA Audio Output Socket
S1 = On-Off Switch

Comments on this post:

There are currently no comments.

Login or Register to post comments.
Click Here