Build Your PC Audio Mixer: A Detailed Circuit Diagram
Description
Most audio cards in computers are configured for mono microphone input, whereas they possess stereo input for high-level signals. The circuit employs the high-level input of the audio card, enabling the connection of two mono microphones to the card’s input. Simultaneously, it offers enhanced functionality through adjustable microphone gain and independent level regulation for each microphone channel. This configuration facilitates the mixing of two mono microphones when desired. Additionally, a classic power supply for Electret microphones is available. The circuit integrates a stereo input Line, equipped with two plug connectors and input level regulation via RV4, simplifying the combination of microphone and Line inputs. The input A uses two RCA female plugs [ JF3-4 ], while input B utilizes a standard 3.5 mm stereo jack. The IC2A-B functions as an adder, driving the stereo output, which emerges from the JF6 jack. JF7 accommodates a power supply exceeding + 9Vdc from an external power pack. This voltage is stabilized to + 5V by the IC3, preventing potential damage to the audio card. If the desired audio level is not achieved, the values of resistors R14-19 and R21 through R24 can be adjusted with smaller or larger values, correspondingly altering the gain of the microphone stage.
Circuit diagram
Parts list
- R1-8-31-32=3.3Kohms
- R2-7-27-30=100ohms
- R3-4-9-10=1Mohms
- R5-11-21-22-23-24=10Kohms
- R6-12-15-17=1Kohms
- R13-14-19-20-28-29=47Kohms
- R18-16-25-26=22Kohms
- RV1=2X100Kohms Lin.
- RV2-3=47Kohms log.
- RV4=2X47Kohms log.
- C1-4-7-9-12-17=10uF 16V
- C2-8=470nF 63V MKT
- C3-24-27-28=100nF 63V MKT
- C5-10=10pF ceramic
- C6-11=1uF 16V
- C13-16-20-21=47pF
- C14-15-18-19=1uF 63V MKT
- C22-23-25=100uF 16V
- C26=4.7uF 16V
- C29=470uF 25V
- IC1=TLC274
- IC2=TLC272
- IC3=7805
- D1=1N4007
- D2=LED 3mm
- JF1-2-5-6=female jack 3.5mm stereo
- JF3-4=RCA female plug
- JF7=female jack 3.5mm mono
All the Resistors are 1/4W 1% metal film