Sound card adapters Several devices can be connected to the audio signal output of a computer sound card at the same time: a tower, a TV, a speaker, etc. Each of these devices puts a certain amount of load on the output and the signal attenuation may be too strong. This circuit is designed to reduce the output impedance of the sound card without causing audible distortion. It is designed to work with stereo systems.
The spindle can be powered from a USB port, of which there are usually several in a PC. It has four 3.5 mm stereo jacks: one input used to input the signal from the card and three outputs connected in parallel. The board is designed to be embedded in a heat shrinkable tube.
The operational amplifiers included in the MCP602 system play the role of voltage amplifiers. They are supplied with 5 V unbalanced voltage, therefore it is necessary to increase the potential at the non-inverting input to approx. 2.5 V. This voltage produces a divider consisting of the resistors R8 and R9. Capacitor C5, together with the internal resistance of this divider, forms a filter that blocks interference that could reach the inputs.