A DIY six-channel stereo speaker selector allows you to share a pair of speakers between six stereo audio systems.
A DIY six-channel stereo speaker selector allows you to share a pair of speakers between six stereo audio systems.
This project is a DIY six-channel stereo speaker selector based on the STC15W201 microcontroller. The purpose of this electronic switch is to distribute a pair of speakers between six stereo audio systems. This is an improved and cheaper version of the 6-channel speaker selector we developed several years ago.
This new speaker selector uses the STC15W201 microcontroller. The MCU is a low-cost 8051 microcontroller developed by STC micro. As of this writing, the STC15W201 is selling for less than $0.80. The design uses the popular 74HC595 8-bit shift register IC to control the seven segments and relays.
We use a pair of 12V DPDT relays to select each speaker channel. These relays interface with the 74HC595 via a 3-channel ULN2001D Darlington transistor array IC. This 3-channel Darlington driver IC is functionally equivalent to the famous 8-channel ULN2003 IC. This version of the ULN2001D is an 8-pin IC available in DIP-8 and SOP-8 packages.
This new board is designed to operate with a 12V DC power supply, and in our prototype we used a 12V/5A SMPS unit to power the entire system.
For best results in this circuit, use an Omron G2R-2-12DC or equivalent type relay with a coil current of less than 100mA.
The STC15W201S firmware is developed using SDCC. For MCU firmware we use stcgal. Thanks to the built-in bootloader, we can program this MCU using a regular 5V USB-UART module/dongle.
The functionality of this firmware is almost identical to the old PIC16F88 firmware. When the system is turned on, the current speaker channel will be displayed on the seven-segment display. To switch to another speaker channel, press the button briefly and several times.
To mute or turn off the current speaker channel, press and hold the same button for more than 3 seconds.
To reduce cost and minimize front panel complexity, we recommend using the seven-segment display dot indicator as the mute indicator. The front panel wiring diagram can be found here.
PCBWay sponsored this project. PCBWay provides high quality PCB manufacturing and assembly services. Additionally, they offer CNC and 3D printing services. The speaker switch board can be ordered from PCBWay. Visit the PCBWay website for manufacturing capabilities and pricing.
This project is an open source hardware project. All design files, schematics and firmware source code are available on Github.com.
The PCB design, schematics and other design files of this project are subject to the CERN-OHL-W 2.0 license. The firmware source code is distributed under the terms of the MIT license.
Post time: May-29-2024