autoaudioswitcher

autoaudioswitcher

Introduction

With vintage amplifiers, you have limited input switching capabilities. And they are all manual. This projects aims to solve this problem.

I have an old kenwood KA-4002 (http://www.hifivintage.eu/product.php?id_product=476) which I love.

So, my solution to this problem, automatic audio input switcher. Basically, the system will detect which audio input has a signal, and switch to it using a solid state MUX.

The project is in early state. Prototype circuit works on a breadbord. First test PCB done and sent to the factory.

Theory of operation

Stereo input is muxed using 10k resistors and AC coupled into an amplifier (saturated). Then, the signal is compared to a reference voltage using a comparator which charges a CAP. A MCU will then poll the charge of the CAP and trigger the MUX (ADG409) to switch on the output if needed. (Programmed in the MCU)

Status

Early design stage.

Breadboard prototype working.

Testing PCB done and sent to the factory. Gerbers available in GERBERS_REV0/.

Tools

KiCAD 20140622 + bzr4027 (r4027)

Hackaday.io entry

http://hackaday.io/project/2282-automatic-audio-input-switcher

OSHW: Automatic audio input switcher based on audio activity